Tag Archives: Amazon Cognito

Implement a full stack serverless search application using AWS Amplify, Amazon Cognito, Amazon API Gateway, AWS Lambda, and Amazon OpenSearch Serverless

Post Syndicated from Anand Komandooru original https://aws.amazon.com/blogs/big-data/implement-a-full-stack-serverless-search-application-using-aws-amplify-amazon-cognito-amazon-api-gateway-aws-lambda-and-amazon-opensearch-serverless/

Designing a full stack search application requires addressing numerous challenges to provide a smooth and effective user experience. This encompasses tasks such as integrating diverse data from various sources with distinct formats and structures, optimizing the user experience for performance and security, providing multilingual support, and optimizing for cost, operations, and reliability.

Amazon OpenSearch Serverless is a powerful and scalable search and analytics engine that can significantly contribute to the development of search applications. It allows you to store, search, and analyze large volumes of data in real time, offering scalability, real-time capabilities, security, and integration with other AWS services. With OpenSearch Serverless, you can search and analyze a large volume of data without having to worry about the underlying infrastructure and data management. An OpenSearch Serverless collection is a group of OpenSearch indexes that work together to support a specific workload or use case. Collections have the same kind of high-capacity, distributed, and highly available storage volume that’s used by provisioned Amazon OpenSearch Service domains, but they remove complexity because they don’t require manual configuration and tuning. Each collection that you create is protected with encryption of data at rest, a security feature that helps prevent unauthorized access to your data. OpenSearch Serverless also supports OpenSearch Dashboards, which provides an intuitive interface for analyzing data.

OpenSearch Serverless supports three primary use cases:

  • Time series – The log analytics workloads that focus on analyzing large volumes of semi-structured, machine-generated data in real time for operational, security, user behavior, and business insights
  • Search – Full-text search that powers applications in your internal networks (content management systems, legal documents) and internet-facing applications, such as ecommerce website search and content search
  • Vector search – Semantic search on vector embeddings that simplifies vector data management and powers machine learning (ML) augmented search experiences and generative artificial intelligence (AI) applications, such as chatbots, personal assistants, and fraud detection

In this post, we walk you through a reference implementation of a full-stack cloud-centered serverless text search application designed to run using OpenSearch Serverless.

Solution overview

The following services are used in the solution:

  • AWS Amplify is a set of purpose-built tools and features that enables frontend web and mobile developers to quickly and effortlessly build full-stack applications on AWS. These tools have the flexibility to use the breadth of AWS services as your use cases evolve. This solution uses the Amplify CLI to build the serverless movie search web application. The Amplify backend is used to create resources such as the Amazon Cognito user pool, API Gateway, Lambda function, and Amazon S3 storage.
  • Amazon API Gateway is a fully managed service that makes it straightforward for developers to create, publish, maintain, monitor, and secure APIs at any scale. We use API Gateway as a “front door” for the movie search application for searching movies.
  • AWS CloudFront accelerates the delivery of web content such as static and dynamic web pages, video streams, and APIs to users across the globe by caching content at edge locations closer to the end-users. This solution uses CloudFront with Amazon S3 to deliver the search application user interface to the end users.
  • Amazon Cognito makes it straightforward for adding authentication, user management, and data synchronization without having to write backend code or manage any infrastructure. We use Amazon Cognito for creating a user pool so the end-user can log in to the movie search application through Amazon Cognito.
  • AWS Lambda is a serverless, event-driven compute service that lets you run code for virtually any type of application or backend service without provisioning or managing servers. Our solution uses a Lambda function to query OpenSearch Serverless. API Gateway forwards all requests to the Lambda function to serve up the requests.
  • Amazon OpenSearch Serverless is a serverless option for OpenSearch Service. In this post, you use common methods for searching documents in OpenSearch Service that improve the search experience, such as request body searches using domain-specific language (DSL) for queries. The query DSL lets you specify the full range of OpenSearch search options, including pagination and sorting the search results. Pagination and sorting are implemented on the server side using DSL as part of this implementation.
  • Amazon Simple Storage Service (Amazon S3) is an object storage service that offers industry-leading scalability, data availability, security, and performance. The solution uses Amazon S3 as storage for storing movie trailers.
  • AWS WAF helps protects web applications from attacks by allowing you to configure rules that allow, block, or monitor (count) web requests based on conditions that you define. We use AWS WAF to allow access to the movie search app from only IP addresses on an allow list.

The following diagram illustrates the solution architecture.

The workflow includes the following steps:

  1. The end-user accesses the CloudFront and Amazon S3 hosted movie search web application from their browser or mobile device.
  2. The user signs in with their credentials.
  3. A request is made to an Amazon Cognito user pool for a login authentication token, and a token is received for a successful sign-in request.
  4. The search application calls the search API method with the token in the authorization header to API Gateway. API Gateway is protected by AWS WAF to enforce rate limiting and implement allow and deny lists.
  5. API Gateway passes the token for validation to the Amazon Cognito user pool. Amazon Cognito validates the token and sends a response to API Gateway.
  6. API Gateway invokes the Lambda function to process the request.
  7. The Lambda function queries OpenSearch Serverless and returns the metadata for the search.
  8. Based on metadata, content is returned from Amazon S3 to the user.

In the following sections, we walk you through the steps to deploy the solution, ingest data, and test the solution.

Prerequisites

Before you get started, make sure you complete the following prerequisites:

  1. Install Nodejs latest LTS version.
  2. Install and configure the AWS Command Line Interface (AWS CLI).
  3. Install awscurl for data ingestion.
  4. Install and configure the Amplify CLI. At the end of configuration, you should successfully set up the new user using the amplify-dev user’s AccessKeyId and SecretAccessKey in your local machine’s AWS profile.
  5. Amplify users need additional permissions in order to deploy AWS resources. Complete the following steps to create a new inline AWS Identity and Access Management (IAM) policy and attach it to the user:
    • On the IAM console, choose Users in the navigation pane.
    • Choose the user amplify-dev.
    • On the Permissions tab, choose the Add permissions dropdown menu, then choose Inline policy.
    • In the policy editor, choose JSON.

You should see the default IAM statement in JSON format.

This environment name needs to be used when performing amplify init when bringing up the backend. The actions in the IAM statement are largely open (*) but restricted or limited by the target resources; this is done to satisfy the maximum inline policy length (2,048 characters).

    • Enter the updated JSON into the policy editor, then choose Next.
    • For Policy name, enter a name (for this post, AddionalPermissions-Amplify).
    • Choose Create policy.

You should now see the new inline policy attached to the user.

Deploy the solution

Complete the following steps to deploy the solution:

  1. Clone the repository to a new folder on your desktop using the following command:
    git clone https://github.com/aws-samples/amazon-opensearchserverless-searchapp.git

  2. Deploy the movie search backend.
  3. Deploy the movie search frontend.

Ingest data

To ingest the sample movie data into the newly created OpenSearch Serverless collection, complete the following steps:

  • On the OpenSearch Service console, choose Ingestion: Pipelines in the navigation pane.
  • Choose the pipeline movie-ingestion and locate the ingestion URL.

  • Replace the ingestion endpoint and Region in the following snippet and run the awscurl command to save data into the collection:
awscurl --service osis --region <region> \
-X POST \
-H "Content-Type: application/json" \
-d "@project_assets/movies-data.json" \
https://<ingest_url>/movie-ingestion/data 

You should see a 200 OK response.

  • On the Amazon S3 console, open the trailer S3 bucket (created as part of the backend deployment.
  • Upload some movie trailers.

Storage

Make sure the file name matches the ID field in sample movie data (for example, tt1981115.mp4, tt0800369.mp4, and tt0172495.mp4). Uploading a trailer with ID tt0172495.mp4 is used as the default trailer for all movies, without having to upload one for each movie.

Test the solution

Access the application using the CloudFront distribution domain name. You can find this by opening the CloudFront console, choosing the distribution, and copying the distribution domain name into your browser.

Sign up for application access by entering your user name, password, and email address. The password should be at least eight characters in length, and should include at least one uppercase character and symbol.

Sign Up

After you’re logged in, you’re redirected to the Movie Finder home page.

Home Page

You can search using a movie name, actor, or director, as shown in the following example. The application returns results using OpenSearch DSL.

Search Results

If there’s a large number of search results, you can navigate through them using the pagination option at the bottom of the page. For more information about how the application uses pagination, see Paginating search results.

Pagination

You can choose movie tiles to get more details and watch the trailer if you took the optional step of uploading a movie trailer.

Movie Details

You can sort the search results using the Sort by feature. The application uses the sort functionality within OpenSearch.

Sort

There are many more DSL search patterns that allow for intricate searches. See Query DSL for complete details.

Monitoring OpenSearch Serverless

Monitoring is an important part of maintaining the reliability, availability, and performance of OpenSearch Serverless and your other AWS services. AWS provides Amazon CloudWatch and AWS CloudTrail to monitor OpenSearch Serverless, report when something is wrong, and take automatic actions when appropriate. For more information, see Monitoring Amazon OpenSearch Serverless.

Clean up

To avoid unnecessary charges, clean up the solution implementation by running the following command at the project root folder you created using the git clone command during deployment:

amplify delete

You can also clean up the solution by deleting the AWS CloudFormation stack you deployed as part of the setup. For instructions, see Deleting a stack on the AWS CloudFormation console.

Conclusion

In this post, we implemented a full-stack serverless search application using OpenSearch Serverless. This solution seamlessly integrates with various AWS services, such as Lambda for serverless computing, API Gateway for constructing RESTful APIs, IAM for robust security, Amazon Cognito for streamlined user management, and AWS WAF for safeguarding the web application against threats. By adopting a serverless architecture, this search application offers numerous advantages, including simplified deployment processes and effortless scalability, with the benefits of a managed infrastructure.

With OpenSearch Serverless, you get the same interactive millisecond response times as OpenSearch Service with the simplicity of a serverless environment. You pay only for what you use by automatically scaling resources to provide the right amount of capacity for your application without impacting performance and scale as needed. You can use OpenSearch Serverless and this reference implementation to build your own full-stack text search application.


About the Authors

Anand Komandooru is a Principal Cloud Architect at AWS. He joined AWS Professional Services organization in 2021 and helps customers build cloud-native applications on AWS cloud. He has over 20 years of experience building software and his favorite Amazon leadership principle is “Leaders are right a lot“.

Rama Krishna Ramaseshu is a Senior Application Architect at AWS. He joined AWS Professional Services in 2022 and with close to two decades of experience in application development and software architecture, he empowers customers to build well architected solutions within the AWS cloud. His favorite Amazon leadership principle is “Learn and Be Curious”.

Sachin Vighe is a Senior DevOps Architect at AWS. He joined AWS Professional Services in 2020, and specializes in designing and architecting solutions within the AWS cloud to guide customers through their DevOps and Cloud transformation journey. His favorite leadership principle is “Customer Obsession”.

Molly Wu is an Associate Cloud Developer at AWS. She joined AWS Professional Services in 2023 and specializes in assisting customers in building frontend technologies in AWS cloud. Her favorite leadership principle is “Bias for Action”.

Andrew Yankowsky is a Security Consultant at AWS. He joined AWS Professional Services in 2023, and helps customers build cloud security capabilities and follow security best practices on AWS. His favorite leadership principle is “Earn Trust”.

How to set up SAML federation in Amazon Cognito using IdP-initiated single sign-on, request signing, and encrypted assertions

Post Syndicated from Vishal Jakharia original https://aws.amazon.com/blogs/security/how-to-set-up-saml-federation-in-amazon-cognito-using-idp-initiated-single-sign-on-request-signing-and-encrypted-assertions/

When an identity provider (IdP) serves multiple service providers (SPs), IdP-initiated single sign-on provides a consistent sign-in experience that allows users to start the authentication process from one centralized portal or dashboard. It helps administrators have more control over the authentication process and simplifies the management.

However, when you support IdP-initiated authentication, the SP (Amazon Cognito in this case) can’t verify that it has solicited the SAML response that it receives from IdP because there is no SAML request initiated from the SP. To accept unsolicited SAML assertions in your user pool, you must consider its effect on your app security. Although your user pool can’t verify an IdP-initiated sign-in session, Amazon Cognito validates your request parameters and SAML assertions.

Amazon Cognito has recently enhanced support for the SAML 2.0 protocol by adding support to IdP-initiated single sign-on (SSO), SAML request signing and accepting encrypted SAML responses.

Amazon Cognito acts as the SP representing your application and generates a token after federation that can be used by the application to access protected backends. The SAML provider acts as an IdP, where the user identities and credentials are stored, and is responsible for authenticating the user.

This post describes the steps to integrate a SAML IdP, Microsoft Entra ID, with an Amazon Cognito user pool and use SAML IdP-initiated SSO flow. It also describes steps to enable signing authentication requests and accepting encrypted SAML responses.

IdP-initiated authentication flow using SAML federation

Figure 1: High-level diagram for SAML IdP-initiated authentication flow in a web or mobile app

Figure 1: High-level diagram for SAML IdP-initiated authentication flow in a web or mobile app

As shown in Figure 1, the high-level flow diagram of an application with federated authentication typically involves the following steps:

  1. An enterprise user opens their SSO portal and signs in. This usually opens a portal with several applications that the user has access to. When the user selects an Amazon Cognito protected application from their SSO portal, an IdP-initiated SSO flow is initiated.
  2. When the user launches an application from the SSO portal, Entra ID sends a SAML assertion to the Cognito endpoint to federate the user.
  3. Amazon Cognito validates the SAML assertion and creates the user in Cognito if this is first-time federation for the user or updates the user’s record if user has signed in before from this IdP. Cognito then generates an authorization code and redirects the user to the application URL with this authorization code. The application exchanges the authorization code for tokens from the Cognito token endpoint.
  4. After the application has tokens, it uses them to authorize access within the application stack as needed.

The SAML response contains claims or assertions that contain user-specific data. The SAML response is transferred over HTTPS to protect confidentiality of the data, but you can also enable encryption to further protect the confidentiality of transferred user information. This enables trusted parties who have the decryption key to decrypt the data. It protects the confidentiality of the data after it’s received by the SP.

Setting up SAML federation between Amazon Cognito and Entra ID

To set up SAML federation and use IdP-initiated SSO, you will complete the following steps:

  1. Create an Amazon Cognito user pool.
  2. Create an app client in the Cognito user pool.
  3. Add Cognito as an enterprise application in Entra ID.
  4. Add Entra ID as the SAML IdP and enable IdP-initiated SSO in Cognito.
  5. Add the newly created SAML IdP to your user pool app client.
  6. Enable encrypting the SAML response.
  7. Add RelayState in Entra ID SAML SSO.

Prerequisites

To implement the solution, you must have the necessary permissions to perform these tasks in Azure portal and in your AWS account.

Step 1: Create an Amazon Cognito user pool

Create a new user pool in Amazon Cognito with the default settings. Make a note of the user pool ID, for example, us-east-1_abcd1234. You will need this value for the next steps.

Add a domain name to user pool

The Cognito user pool’s hosted UI can be used as the OAuth 2.0 authorization server with a customizable web interface for sign-up and sign-in. Cognito OAuth 2.0 endpoints are accessible from a domain name that must be added to the user pool. There are two options for adding a domain name to a user pool. You can either use a Cognito domain or a domain name that you own. This solution uses a Cognito domain, which will look like the following:

https://<yourDomainPrefix>.auth.<aws-region>.amazoncognito.com

To add a domain name to a user pool:

  1. In the AWS Management Console for Amazon Cognito, navigate to the App integration tab for your user pool.
  2. On the right side of the pane, choose Actions and select Create Cognito domain.

    Figure 2: Create a Cognito domain

    Figure 2: Create a Cognito domain

  3. Enter an available domain prefix (for example example-corp-prd) to use with the Cognito domain.

    Figure 3: Add a domain prefix

    Figure 3: Add a domain prefix

  4. Choose Create Cognito domain.

Step 2: Create an app client in the Cognito user pool

Before you can use Amazon Cognito in your web application, you must register your app with Amazon Cognito as an app client. The IdP-initiated SAML flow can’t be enabled on one app client with the other SP-initiated authentication SAML IdPs or social IdPs. IdP-initiated SAML introduces additional risks that other SSO providers aren’t subject to. For example, it’s not possible to add a state parameter, which is usually used for cross-site request forgery (CSRF) mitigation. Because of this, you can’t add IdPs that aren’t SAML, including the user pool itself, to an app client that uses a SAML provider with IdP-initiated SSO.

To create an app client:

  1. In the Amazon Cognito console, navigate to the App integration tab for the same user pool and locate App clients. Choose Create an app client.
  2. Select an Application type. For this example, create a public client.
  3. Enter an App client name.
  4. Choose Don’t generate client secret.
  5. Keep the rest of the settings as default.
  6. Under Hosted UI settings, add Allowed callback URLs for your app client. This is where you will be directed after authentication.
  7. Choose Authorization code grant for OAuth 2.0 grant types.
  8. You can keep the remaining configuration as default and choose Create app client.

After the app client is successfully created, capture the app client ID from the App integration tab of the user pool.

Prepare information for the Entra ID setup

Prepare the Identifier (Entity ID) and Reply URL, which are required to add Amazon Cognito as an enterprise application in Entra ID (Step 3).

Create values for Identifier (Entity ID) and Reply URL according to the following formats:

For Identifier (Entity ID), the format is:
urn:amazon:cognito:sp:<yourUserPoolID>

For example: urn:amazon:cognito:sp:us-east-1_abcd1234

For Reply URL, the format is:
https://<yourDomainPrefix>.auth.<aws-region>.amazoncognito.com/saml2/idpresponse

For example: https://example-corp-prd.auth.us-east-1.amazoncognito.com/saml2/idpresponse

The reply URL is the endpoint where Entra ID will send the SAML assertion to Amazon Cognito during user authentication.

For more information, see Adding SAML identity providers to a user pool.

Step 3: Add Amazon Cognito as an enterprise application in Entra ID

With the user pool and app client created and the information for Entra ID prepared, you can add Amazon Cognito as an application in Entra ID. To complete this step, you will add Cognito as an enterprise application and set up SSO.

To add Cognito as an enterprise application

  1. Sign in to the Azure portal.
  2. In the search box, search for the service Microsoft Entra ID.
  3. In the left sidebar, select Enterprise applications.
  4. Choose New application.
  5. On the Browse Microsoft Entra Gallery page, choose Create your own application.

    Figure 4: Create an application in Entra ID

    Figure 4: Create an application in Entra ID

  6. Under What’s the name of your app?, enter a name for your application and select Integrate any other application you don’t find in the gallery (Non-gallery), as shown in Figure 4. Choose Create.
  7. It will take few seconds for the application to be created in Entra ID, and then you should be redirected to the Overview page for the newly added application.

To set up SSO using SAML:

  1. On the Getting started page, in the Set up single sign on tile, choose Get started, as shown in Figure 5.

    Figure 5: Choose Set up single sign-on in Getting Started

    Figure 5: Choose Set up single sign-on in Getting Started

  2. On the next screen, select SAML.
  3. In the middle pane under Set up Single Sign-On with SAML, in the Basic SAML Configuration section, choose the edit icon.
  4. In the right pane under Basic SAML Configuration, replace the default Identifier ID (Entity ID) with the identifier (entity ID) you created in Step 2. Replace Reply URL (Assertion Consumer Service URL) with the reply URL you created in Step 2.

    Figure 6: Add the identifier (entity ID) and reply URL

    Figure 6: Add the identifier (entity ID) and reply URL

  5. Now go to Attributes & Claims and note the claims, as shown in Figure 7. You’ll need these when creating attribute mapping in Amazon Cognito.

    Figure 7: Entra ID Attributes & Claims

    Figure 7: Entra ID Attributes & Claims

  6. Scroll down to the SAML Certificates section and copy the App Federation Metadata Url by choosing the copy into clipboard icon. Make a note of this URL to use in the next step.

    Figure 8: Copy SAML metadata URL from Entra ID

    Figure 8: Copy SAML metadata URL from Entra ID

Step 4: Add Entra ID as SAML IdP in Amazon Cognito

In this step, you’ll add Entra ID as a SAML IdP to your user pool and download the signing and encryption certificates.

To add the SAML IdP:

  1. In the Amazon Cognito console, navigate to the Sign-in experience tab of the same user pool. Locate Federated identity provider sign-in and choose Add an Identity provider.
  2. Choose a SAML IdP.
  3. Enter a Provider name, for example, EntraID.
  4. Under IdP-initiated SAML sign-in, choose Accept SP-initiated and IdP-initiated SAML assertions.
  5. Under Metadata document source, enter the metadata document endpoint URL you captured in Step 3.
  6. (Optional) Under SAML signing and encryption, select Require encrypted SAML assertion from this provider.

    Enable Required encrypted SAML assertion from this provider only if you can turn on token encryption in the Entra ID application. See Step 6.

  7. Under Map attributes between your SAML provider and your user pool to map SAML provider attributes to the user profile in your user pool. Include your user pool required attributes in your attribute map.

    For example, when you choose User pool attribute email, enter the SAML attribute name as it appears in the SAML assertion from your IdP. In our case it will be http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress.

    Figure 9: Enter the SAML attribute name

    Figure 9: Enter the SAML attribute name

  8. Choose Add identity provider.

After the IdP has been created, you can navigate to the recently added EntraID IdP in the user pool for downloading the SAML signing and encryption certificate. These certificates must be imported into the Entra ID enterprise application.

To download the certificates

  1. To download the SAML signing certificate, Choose View signing certificate and Download as .crt
  2. To download the SAML encryption certificate, Choose View encryption certificate and Download as .crt.

Step 5: Add the newly created SAML IdP to your user pool app client

Before you can use Amazon Cognito in your web application, you must add the SAML IdP created in Step 4 to your app client.

To add the SAML IdP:

  1. In the Amazon Cognito console, navigate to the App integration tab for the same user pool and locate App clients.
  2. Choose the app client you created in Step 2.
  3. Locate the Hosted UI section and choose Edit.
  4. Under Identity providers, select the identity provider you created in Step 4 and choose Save changes.

    Figure 10: Enabling the Entra ID SAML identity provider in the Cognito app client

    Figure 10: Enabling the Entra ID SAML identity provider in the Cognito app client

At this stage, the Amazon Cognito OAuth 2.0 server is up and running and the web interface is accessible and ready to use. You can access the Cognito hosted UI from your app client using the Cognito console to test it further.

Step 6: Enable encrypting the SAML response in EntraID

For additional security and privacy of user data, enable encrypting the SAML response. Amazon Cognito and your IdP can establish confidentiality in SAML responses when users sign in and sign out. Cognito assigns a public-private RSA key pair and a certificate to each external SAML provider that you configure in your user pool. You will use the SAML encryption certificate downloaded in step 4.

To enable encrypting the SAML response:

  1. Navigate to your Enterprise application in Entra ID and in the left menu, under Security, select Token encryption.
  2. Import the SAML encryption certificate you have already downloaded in step 4.

    Figure 11: Import the Cognito encryption certificate to Entra ID

    Figure 11: Import the Cognito encryption certificate to Entra ID

  3. After the certificate is imported, it’s inactive by default. To activate it, right-click on the certificate and select Activate token encryption certificate. This enables the encrypted SAML response.

    Figure 12: Activate the token encryption certificate in Entra ID

    Figure 12: Activate the token encryption certificate in Entra ID

Step 7: Add RelayState in Entra ID SAML SSO

A RelayState parameter is required when using SAML IdP-initiated authentication flow. Set this up in Entra ID for the Amazon Cognito user pool and the enabled app client ID.

To add RelayState in Entra ID SAML SSO:

  1. Sign in to the Azure portal and open the enterprise application created in Step 3.
  2. In the left sidebar, choose Single sign-on.
  3. In the middle pane under Set up Single Sign-On with SAML, in the Basic SAML Configuration section, choose the edit icon.
  4. In the right pane under Basic SAML Configuration, apply the value as the format below to the Relay State (Optional) field.
    identity_provider=<IDProviderName>&client_id=<ClientId>&redirect_uri=<callbackURL>&response_type=code&scope=openid+email+phone

    1. Replace <IDProviderName> with the name you previously used for ID provider.
    2. Replace <ClientId> with the app client’s ClientID created in Step 2.
    3. Replace <ecallbackURL> with the URL of your web application that will receive the authorization code. It must be an HTTPS endpoint, except for in a local development environment where you can use http://localhost:PORT_NUMBER.

    For example:

    identity_provider=EntraID&client_id=abcd1234567&redirect_uri=https://example.com&response_type=code&scope=openid+email+phone

    Figure 13: Set RelayState in Entra ID single sign-on

    Figure 13: Set RelayState in Entra ID single sign-on

Test the IdP-initiated flow

Next, do a quick test to check if everything is configured properly.

  1. Sign in to the Azure portal and open the Enterprise application created in Step 3.
  2. In the left sidebar, choose Users and groups.
  3. On the right side, choose Add user/group. This will show the Add Assignment page.
  4. From the left side of the page, choose None Selected .
  5. Select a user from the right of the screen and follow the prompt to assign the user for this application.
  6. Once the user is assigned successfully, open https://www.microsoft365.com/apps and sign in as the assigned user.
  7. After you are signed in, choose the application icon registered as the IdP-initiated SSO.

    Figure 14: Testing IdP-initiated SSO from an Office 365 application

    Figure 14: Testing IdP-initiated SSO from an Office 365 application

  8. The application will start the IdP-initiated authentication flow and the user will be redirected to the application as a signed-in user.

Signing an authentication request in case of SP-initiated flow

The preceding authentication flow that you tested uses IdP-initiated SSO. If you’re using an SP-initiated flow, you can enable signing of the SAML request that is sent from the SP (Amazon Cognito) to the IdP (Entra ID) for additional security and integrity of communication between them.

You can enable the authentication request signing in Cognito while creating the IdP or by updating your existing IdP.

To enable signing of the SAML request:

  1. In the Amazon Cognito console, when you create or edit your SAML identity provider, under SAML signing and encryption, select the box Sign SAML requests to this provider and choose Save changes.

    Figure 15: Enabling signing SAML request

    Figure 15: Enabling signing SAML request

  2. Sign in to the Azure portal and access your Entra ID enterprise application. Go to Set up single sign on and edit Verification certificates (optional).
  3. Select the checkbox Require verification certificates and upload the Cognito user pool SAML signing certificate already downloaded in Step 4 with a .cer file extension. You must convert the .crt file to a .cer file because Entra ID requires a verification certificate in a .cer extension.

To convert the .crt certificate extension to .cer:

  1. Right-click the .crt file and choose Open.
  2. Navigate to the Details tab.
  3. Select Copy to File… and choose Next.
  4. Select Base-64 encoded X.509 (.CER) and choose Next.
  5. Give your export file a name (for example, Entra ID.cer) and choose Save.
  6. Choose Next.
  7. Confirm the details and choose Finish.

Test the SP-initiated flow

Next, do a quick test to check if everything is configured properly.

  1. In the Amazon Cognito console, navigate to the App integration tab for the same user pool and locate App clients.
  2. Choose the app client you created in Step 2.
  3. Locate the Hosted UI section and choose View Hosted UI.
  4. From the hosted UI, authenticate yourself using Entra ID as the identity provider.
  5. After authentication is completed successfully, you will be redirected to the callback URL you configured in your app client with the authorization code.

If you capture the SAML request, you will see that Amazon Cognito is sending a cryptographic signature with the signing certificate in the SAML request to the IdP, and the IdP will match the cryptographic signature with the uploaded certificate to ensure the integrity of the request.

Conclusion

In this post, you learned the benefits of using IdP-initiated single sign-on. It helps centralize administration and lowers dependency on service provider applications. Also, you learned how to integrate an Amazon Cognito user pool with Microsoft Entra ID as an external SAML IdP using IdP-initiated SSO so your users can use their corporate ID to sign in to web or mobile applications. Also, you learned about how to enable signed authentication requests when using an SP-initiated flow and encrypting SAML responses for additional security between Cognito and the SAML IdP.

 
If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, contact AWS Support.

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Vishal Jakharia

Vishal Jakharia

Vishal is a cloud support engineer based in New Jersey, USA. He is an Amazon Cognito subject matter expert who loves to work with customers and provide them solutions for implementing authentication and authorization. He helps customers migrate and build secure scalable architecture on the AWS Cloud.

Yungang Wu

Yungang Wu

Yungang is a senior cloud support engineer who specializes in the Amazon Cognito service. He helps AWS customers troubleshoot issues and suggests well-designed application authentication and authorization implementations.

How to use WhatsApp to send Amazon Cognito notification messages

Post Syndicated from Nideesh K T original https://aws.amazon.com/blogs/security/how-to-use-whatsapp-to-send-amazon-cognito-notification-messages/

While traditional channels like email and SMS remain important, businesses are increasingly exploring alternative messaging services to reach their customers more effectively. In recent years, WhatsApp has emerged as a simple and effective way to engage with users. According to statista, as of 2024, WhatsApp is the most popular mobile messenger app worldwide and has reached over two billion monthly active users in January 2024.

Amazon Cognito lets you add user sign-up and authentication to your mobile and web applications. Among many other features, Cognito provides a custom SMS sender AWS Lambda trigger for using third-party providers to send notifications. In this post, we’ll be using WhatsApp as the third-party provider to send verification codes or multi-factor authentication (MFA) codes instead of SMS during Cognito user pool sign up.

Note: WhatsApp is a third-party service subject to additional terms and charges. Amazon Web Services (AWS) isn’t responsible for third-party services that you use to send messages with a custom SMS sender in Amazon Cognito.

Overview

By default, Amazon Cognito uses Amazon Simple Notification Service (Amazon SNS) for delivery of SMS text messages. Cognito also supports custom triggers that will allow you to invoke an AWS Lambda function to support additional providers such as WhatsApp.

The architecture shown in Figure 1 depicts how to use a custom SMS sender trigger and WhatsApp to send notifications. The steps are as follows:

  1. A user signs up to an Amazon Cognito user pool.
  2. Cognito invokes the custom SMS sender Lambda function and sends the user’s attributes, including the phone number and a one-time code to the Lambda function. This one-time code is encrypted using a custom symmetric encryption AWS Key Management Service (AWS KMS) key that you create.
  3. The Lambda function decrypts the one-time code using a Decrypt API call to your AWS KMS key.
  4. The Lambda function then obtains the WhatsApp access token from AWS Secrets Manager. The WhatsApp access token needs to be generated through Meta Business Settings (which are covered in the next section) and added to Secrets Manager. Lambda also parses the phone number, user attributes, and encrypted secrets.
  5. Lambda sends a POST API call to the WhatsApp API and WhatsApp delivers the verification code to the user as a message. The user can then use the verification code to verify their contact information and confirm the sign-up.

Figure 1: Custom SMS sender trigger flow

Figure 1: Custom SMS sender trigger flow

Prerequisites

Implementation

In the next steps, we look at how to create a Meta app, create a new system user, get the WhatsApp access token and create the template to send the WhatsApp token.

Create and configure an app for WhatsApp communication

To get started, create a Meta app with WhatsApp added to it, along with the customer phone number that will be used to test.

To create and configure an app

  1. Open the Meta for Developers console, choose My Apps and then choose Create App (or choose an existing Business type app and skip to step 4).
  2. Select Other choose Next and then select Business as the app type and choose Next.
  3. Enter an App name, App contact email, choose whether or not to attach a Business portfolio and choose Create app.
  4. Open the app Dashboard and in the Add product to your app section, under WhatsApp, choose Set up.
  5. Create or select an existing Meta business portfolio and choose Continue.
  6. In the left navigation pane, under WhatsApp, choose API Setup.
  7. Under Send and receive messages, take a note of the Phone number ID, which will be needed in the AWS CDK template later.
  8. Under To, add the customer phone number you want to use for testing. Follow the instructions to add and verify the phone number.

Note: You must have WhatsApp registered with the number and the WhatsApp client installed on your mobile device.

Create a user for accessing WhatsApp

Create a system user in Meta’s Business Manager and assign it to the app created in the previous step. The access tokens generated for this user will be used to make the WhatsApp API calls.

To create a user

  1. Open Meta’s Business Manager and select the business you created or associated your application with earlier from the dropdown menu under Business settings.
  2. Under Users, select System users and then choose Add to create a new system user.
  3. Enter a name for the System Username and set their role as Admin and choose Create system user.
  4. Choose Assign assets.
  5. From the Select asset type list, select Apps. Under Select assets, select your WhatsApp application’s name. Under Partial access, turn on the Test app option for the user. Choose Save Changes and then choose Done.
  6. Choose Generate New Token, select the WhatsApp application created earlier, and leave the default 60 days as the token expiration. Under Permissions select WhatsApp_business_messaging and WhatsApp_business_management and choose Generate Token at the bottom.
  7. Copy and save your access token. You will need this for the AWS CDK template later. Choose OK. For more details on creating the access token, see WhatsApp’s Business Management API Get Started guide.

Create a template in WhatsApp

Create a template for the verification messages that will be sent by WhatsApp.

To create a template

  1. Open Meta’s WhatsApp Manager.
  2. On the left icon pane, under Account tools, choose Message template and then choose Create Template.
  3. Select Authentication as the category.
  4. For the Name, enter otp_message.
  5. For Languages, enter English.
  6. Choose Continue.
  7. In the next screen, select Copy code and choose Submit.

Note: It’s possible that Meta might change the process or the UI. See the Meta documentation for specific details.

For more information on WhatsApp templates, see Create and Manage Templates.

Create a Secrets Manager secret

Use the Secrets Manager console to create a Secrets Manager secret and set the secret to the WhatsApp access token.

To create a secret

  1. Open the AWS Management Console and go to Secrets Manager.

    Figure 2: Open the Secrets Manager console

    Figure 2: Open the Secrets Manager console

  2. Choose Store a new secret.

    Figure 3: Store a new secret

    Figure 3: Store a new secret

  3. Under Choose a secret type, choose Other type of secret and under Key/value pairs, select the Plaintext tab and enter Bearer followed by the WhatsApp access token (Bearer <WhatsApp access token>).

    Figure 4: Add the secret

    Figure 4: Add the secret

  4. For the encryption key, you can use either the AWS KMS key that Secrets Manager creates or a customer managed AWS KMS key that you create and then choose Next.
  5. Provide the secret name as the WhatsAppAccessToken, choose Next, and then choose Store to create the secret.
  6. Note the secret Amazon Resource Name (ARN) to use in later steps.

Deploy the solution

In this section, you clone the GitHub repository and deploy the stack to create the resources in your account.

To clone the repository

  1. Create a new directory, navigate to that directory in a terminal and use the following command to clone the GitHub repository that has the Lambda and AWS CDK code:
  2. Change directory to the pattern directory:
    cd amazon-cognito-whatsapp-otp

To deploy the stack

  1. Configure the phone number ID obtained from WhatsApp, the secret name, secret ARN, and the Amazon Cognito user pool self-service sign-up option in the constants.ts file.

    Open the lib/constants.ts file and edit the fields. The SELF_SIGNUP value must be set to true for the purpose of this proof of concept. The SELF_SIGNUP value represents the Boolean value for the Amazon Cognito user pool sign-up option, which when set to true allows public users to sign up.

    export const PHONE_NUMBER_ID = '<phone number ID>'; 
    export const SECRET_NAME = '<WhatsAppAccessToken>'; 
    export const SECRET_ARN = 'arn:aws:secretsmanager:<AWSRegion>:<phone number ID>:secret:<WhatsAppAccessToken>'; 
    export const SELF_SIGNUP = <true>;

    Warning: If you activate user sign-up (enable self-registration) in your user pool, anyone on the internet can sign up for an account and sign in to your applications.

  2. Install the AWS CDK required dependencies by running the following command:
    npm install

  3. This project uses typescript as the client language for AWS CDK. Run the following command to compile typescript to JavaScript:
    npm run build

  4. From the command line, configure AWS CDK (if you have not already done so):
    cdk bootstrap <account number>/<AWS Region>

  5. Install and run Docker. We’re using the aws-lambda-python-alpha package in the AWS CDK code to build the Lambda deployment package. The deployment package installs the required modules in a Lambda compatible Docker container.
  6. Deploy the stack:
    cdk synth
    cdk deploy --all

Test the solution

Now that you’ve completed implementation, it’s time to test the solution by signing up a user on Amazon Cognito and confirming that the Lambda function is invoked and sends the verification code.

To test the solution

  1. Open AWS CloudFormation console.
  2. Select the WhatsappOtpStack that was deployed through AWS CDK.
  3. On the Outputs tab, copy the value of cognitocustomotpsenderclientappid.
  4. Run the following AWS Command Line Interface (AWS CLI) command, replacing the client ID with the output of cognitocustomotpsenderclientappid, username, password, email address, name, phone number, and AWS Region to sign up a new Amazon Cognito user.
    aws cognito-idp sign-up --client-id <cognitocustomsmssenderclientappid> --username <TestUserPhoneNumber> --password <Password> --user-attributes Name="email",Value="<TestUserEmail>" Name="name",Value="<TestUserName>" Name="phone_number",Value="<TestPhoneNumber>" --region <AWS Region>

    Example:

    aws cognito-idp sign-up --client-id xxxxxxxxxxxxxx --username +12065550100  --password Test@654321 --user-attributes Name="email",Value="[email protected]" Name="name",Value="Jane" Name="phone_number",Value=”+12065550100" --region us-east-1

    Note: Password requirements are a minimum length of eight characters with at least one number, one lowercase letter, and one special character.

The new user should receive a message on WhatsApp with a verification code that they can use to complete their sign-up.

Cleanup

  1. Run the following command to delete the resources that were created. It might take a few minutes for the CloudFormation stack to be deleted.
    cdk destroy --all

  2. Delete the secret WhatsAppAccessToken that was created from the Secrets Manager console.

Conclusion

In this post, we showed you how to use an alternative messaging platform such as WhatsApp to send notification messages from Amazon Cognito. This functionality is enabled through the Amazon Cognito custom SMS sender trigger, which invokes a Lambda function that has the custom code to send messages through the WhatsApp API. You can use the same method to use other third-party providers to send messages.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, start a new thread on the Amazon Cognito re:Post or contact AWS Support.

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Nideesh K T

Nideesh K T

Nideesh is an experienced IT professional with expertise in cloud computing and technical support. Nideesh has been working in the technology industry for 8 years. In his current role as a Sr. Cloud Support Engineer, Nideesh provides technical assistance and troubleshooting for cloud infrastructure issues. Outside of work, Nideesh enjoys staying active by going to the gym, playing sports, and spending time outdoors.

Reethi Joseph

Reethi Joseph

Reethi is a Sr. Cloud Support Engineer at AWS with 7 years of experience specializing in serverless technologies. In her role, she helps customers architect and build solutions using AWS services. When not delving into the world of servers and generative AI, she spends her time trying to perfect her swimming strokes, traveling, trying new baking recipes, gardening, and watching movies.

Authorize API Gateway APIs using Amazon Verified Permissions and Amazon Cognito

Post Syndicated from Kevin Hakanson original https://aws.amazon.com/blogs/security/authorize-api-gateway-apis-using-amazon-verified-permissions-and-amazon-cognito/

Externalizing authorization logic for application APIs can yield multiple benefits for Amazon Web Services (AWS) customers. These benefits can include freeing up development teams to focus on application logic, simplifying application and resource access audits, and improving application security by using continual authorization. Amazon Verified Permissions is a scalable permissions management and fine-grained authorization service that you can use for externalizing application authorization. Along with controlling access to application resources, you can use Verified Permissions to restrict API access to authorized users by using Cedar policies. However, a key challenge in adopting an external authorization system like Verified Permissions is the effort involved in defining the policy logic and integrating with your API. This blog post shows how Verified Permissions accelerates the process of securing REST APIs that are hosted on Amazon API Gateway for Amazon Cognito customers.

Setting up API authorization using Amazon Verified Permissions

As a developer, there are several tasks you need to do in order to use Verified Permissions to store and evaluate policies that define which APIs a user is permitted to access. Although Verified Permissions enables you to decouple authorization logic from your application code, you may need to spend time up front integrating Verified Permissions with your applications. You may also need to spend time learning the Cedar policy language, defining a policy schema, and authoring policies that enforce access control on APIs. Lastly, you may need to spend additional time developing and testing the AWS Lambda authorizer function logic that builds the authorization request for Verified Permissions and enforces the authorization decision.

Getting started with the simplified wizard

Amazon Verified Permissions now includes a console-based wizard that you can use to quickly create building blocks to set up your application’s API Gateway to use Verified Permissions for authorization. Verified Permissions generates an authorization model based on your APIs and policies that allows only authorized Cognito groups access to your APIs. Additionally, it deploys a Lambda authorizer, which you attach to the APIs you want to secure. After the authorizer is attached, API requests are authorized by Verified Permissions. The generated Cedar policies and schema flatten the learning curve, yet allow you full control to modify and help you adhere to your security requirements.

Overview of sample application

In this blog post, we demonstrate how you can simplify the task of securing permissions to a sample application API by using the Verified Permissions console-based wizard. We use a sample pet store application which has two resources:

  1. PetStorePool – An Amazon Cognito user pool with users in one of three groups: customers, employees, and owners.
  2. PetStore – An Amazon API Gateway REST API derived from importing the PetStore example API and extended with a mock integration for administration. This mock integration returns a message with a URI path that uses {“statusCode”: 200} as the integration request and {“Message”: “User authorized for $context.path”} as the integration response.

The PetStore has the following four authorization requirements that allow access to the related resources. All other behaviors should be denied.

  1. Both authenticated and unauthenticated users are allowed to access the root URL.
    • GET /
  2. All authenticated users are allowed to get the list of pets, or get a pet by its identifier.
    • GET /pets
    • GET /pets/{petid}
  3. The employees and owners group are allowed to add new pets.
    • POST /pets
  4. Only the owners group is allowed to perform administration functions. These are defined using an API Gateway proxy resource that enables a single integration to implement a set of API resources.
    • ANY /admin/{proxy+}

Walkthrough

Verified Permissions includes a setup wizard that connects a Cognito user pool to an API Gateway REST API and secures resources based on Cognito group membership. In this section, we provide a walkthrough of the wizard that generates authorization building blocks for our sample application.

To set up API authorization based on Cognito groups

  1. On the Amazon Verified Permissions page in the AWS Management Console, choose Create a new policy store.
  2. On the Specify policy store details page under Starting options, select Set up with Cognito and API Gateway, and then choose Next.

    Figure 1: Starting options

    Figure 1: Starting options

  3. On the Import resources and actions page under API Gateway details, select the API and Deployment stage from the dropdown lists. (A REST API stage is a named reference to a deployment.) For this example, we selected the PetStore API and the demo stage.

    Figure 2: API Gateway and deployment stage

    Figure 2: API Gateway and deployment stage

  4. Choose Import API to generate a Map of imported resources and actions. For our example, this list includes Action::”get /pets” for getting the list of pets, Action::”get /pets/{petId}” for getting a single pet, and Action::”post /pets” for adding a new pet. Choose Next.

    Figure 3: Map of imported resources and actions

    Figure 3: Map of imported resources and actions

  5. On the Choose identity source page, select an Amazon Cognito user pool (PetStorePool in our example). For Token type to pass to API, select a token type. For our example, we chose the default value, Access token, because Cognito recommends using the access token to authorize API operations. The additional claims available in an id token may support more fine-grained access control. For Client application validation, we also specified the default, to not validate that tokens match a configured app client ID. Consider validation when you have multiple user pool app clients configured with different permissions.

    Figure 4: Choose Cognito user pool as identity source

    Figure 4: Choose Cognito user pool as identity source

  6. Choose Next.
  7. On the Assign actions to groups page under Group selection, choose the Cognito user pool groups that can take actions in the application. This solution uses native Cognito group membership to control permissions. In Figure 5, the customers group is not used for access control, we deselected it and it isn’t included in the generated policies. Instead, access to get /pets and get/pets/{petId} is granted to all authenticated users using a different authorizer that we define later in this post.

    Figure 5: Assign actions to groups

    Figure 5: Assign actions to groups

  8. For each of the groups, choose which actions are allowed. In our example, post /pets is the only action selected for the employees group. For the owners group, all of the /admin/{proxy+} actions are additionally selected. Choose Next.

    Figure 6: Groups employees and owners

    Figure 6: Groups employees and owners

  9. On the Deploy app integration page, review the API Gateway Integration details. Choose Create policy store.

    Figure 7: API Gateway integration

    Figure 7: API Gateway integration

  10. On the Create policy store summary page, review the progress of the setup. Choose Check deployment to check the progress of Lambda authorizer.

    Figure 8: Create policy store

    Figure 8: Create policy store

The setup wizard deployed a CloudFormation stack with a Lambda authorizer. This authorizes access to the API Gateway resources for the employees and owners groups. For the resources that should be authorized for all authenticated users, a separate Cognito User Pool authorizer is required. You can use the following AWS CLI apigateway create-authorizer command to create the authorizer.

aws apigateway create-authorizer \
--rest-api-id wrma51eup0 \
--name "Cognito-PetStorePool" \
--type COGNITO_USER_POOLS \
--identity-source "method.request.header.Authorization" \
--provider-arns "arn:aws:cognito-idp:us-west-2:000000000000:userpool/us-west-2_iwWG5nyux"

After the CloudFormation stack deployment completes and the second Cognito authorizer is created, there are two authorizers that can be attached to PetStore API resources, as shown in Figure 9.

Figure 9: PetStore API Authorizers

Figure 9: PetStore API Authorizers

In Figure 9, Cognito-PetStorePool is a Cognito user pool authorizer. Because this example uses an access token, an authorization scope (for example, a custom scope like petstore/api) is specified when attached to the GET /pets and GET /pets/{petId} resources.

AVPAuthorizer-XXX is a request parameter-based Lambda authorizer, which determines the caller’s identity from the configured identity sources. In Figure 9, these sources are Authorization (Header), httpMethod (Context), and path (Context). This authorizer is attached to the POST /pets and ANY /admin/{proxy+} resources. Authorization caching is initially set at 120 seconds and can be configured using the API Gateway console.

This combination of multiple authorizers and caching reduces the number of authorization requests to Verified Permissions. For API calls that are available to all authenticated users, using the Cognito-PetStorePool authorizer instead of a policy permitting the customers group helps avoid chargeable authorization requests to Verified Permissions. Applications where the users initiate the same action multiple times or have a predictable sequence of actions will experience high cache hit rates. For repeated API calls that use the same token, AVPAuthorizer-XXX caching results in lower latency, fewer requests per second, and reduced costs from chargeable requests. The use of caching can delay the time between policy updates and policy enforcement, meaning that the policy updates to Verified Permissions are not realized until the timeout or the FlushStageAuthorizersCache API is called.

Deployment architecture

Figure 10 illustrates the runtime architecture after you have used the Verified Permissions setup wizard to perform the deployment and configuration steps. After the users are authenticated with the Cognito PetStorePool, API calls to the PetStore API are authorized with the Cognito access token. Fine-grained authorization is performed by Verified Permissions using a Lambda authorizer. The wizard automatically created the following four items for you, which are labelled in Figure 10:

  1. A Verified Permissions policy store that is connected to a Cognito identity source.
  2. A Cedar schema that defines the User and UserGroup entities, and an action for each API Gateway resource.
  3. Cedar policies that assign permissions for the employees and owners groups to related actions.
  4. Lambda authorizer that is configured on the API Gateway.

Figure 10: Architecture diagram after deployment

Figure 10: Architecture diagram after deployment

Verified Permissions uses the Cedar policy language to define fine-grained permissions. The default decision for an authorization response is “deny.” The Cedar policies that are generated by the setup wizard can determine an “allow” decision. The principal for each policy is a UserGroup entity with an entity ID format of {user pool id}|{group name}. The action IDs for each policy represent the set of selected API Gateway HTTP methods and resource paths. Note that post /pets is permitted for both employees and owners. The resource in the policy scope is unspecified, because the resource is implicitly the application.

permit (
    principal in PetStore::UserGroup::"us-west-2_iwWG5nyux|employees",
    action in [PetStore::Action::"post /pets"],
    resource
);

permit (
    principal in PetStore::UserGroup::"us-west-2_iwWG5nyux|owners",
    action in
        [PetStore::Action::"delete /admin/{proxy+}",
         PetStore::Action::"post /admin/{proxy+}",
         PetStore::Action::"get /admin/{proxy+}",
         PetStore::Action::"patch /admin/{proxy+}",
         PetStore::Action::"put /admin/{proxy+}",
         PetStore::Action::"post /pets"],
    resource
);

Validating API security

A set of terminal-based curl commands validate API security for both authorized and unauthorized users, by using different access tokens. For readability, a set of environment variables is used to represent the actual values. TOKEN_C, TOKEN_E, and TOKEN_O contain valid access tokens for respective users in the customers, employees, and owners groups. API_STAGE is the base URL for the PetStore API and demo stage that we selected earlier.

To test that an unauthenticated user is allowed for the GET / root path (Requirement 1 as described in the Overview section of this post), but not allowed to call the GET /pets API (Requirement 2), run the following curl commands. The Cognito-PetStorePool authorizer should return {“message”:”Unauthorized”}.

curl -X GET ${API_STAGE}/
<html>
...Welcome to your Pet Store API...
</html>

curl -X GET ${API_STAGE}/pets
{"message":"Unauthorized"}

To test that an authenticated user is allowed to call the GET /pets API (Requirement 2) by using an access token (due to the Cognito-PetStorePool authorizer), run the following curl commands. The user should receive an error message when they try to call the POST /pets API (Requirement 3), because of the AVPAuthorizer. There are no Cedar polices defined for the customers group with the action post /pets.

curl -H "Authorization: Bearer ${TOKEN_C}" -X GET ${API_STAGE}/pets
[
  {
    "id": 1,
    "type": "dog",
    "price": 249.99
  },
  {
    "id": 2,
    "type": "cat",
    "price": 124.99
  },
  {
    "id": 3,
    "type": "fish",
    "price": 0.99
  }
]

curl -H "Authorization: Bearer ${TOKEN_C}" -X POST ${API_STAGE}/pets
{"Message":"User is not authorized to access this resource with an explicit deny"}

The following commands will verify that a user in the employees group is allowed the post /pets action (Requirement 3).

curl -H "Authorization: Bearer ${TOKEN_E}" \
     -H "Content-Type: application/json" \
     -d '{"type": "dog","price": 249.99}' \
     -X POST ${API_STAGE}/pets
{
  "pet": {
    "type": "dog",
    "price": 249.99
  },
  "message": "success"
}

The following commands will verify that a user in the employees group is not authorized for the admin APIs, but a user in the owners group is allowed (Requirement 4).

curl -H "Authorization: Bearer ${TOKEN_E}" -X GET ${API_STAGE}/admin/curltest1
{"Message":"User is not authorized to access this resource with an explicit deny"} 

curl -H "Authorization: Bearer ${TOKEN_O}" -X GET ${API_STAGE}/admin/curltest1
{"Message": "User authorized for /demo/admin/curltest1"}

Try it yourself

How could this work with your user pool and REST API? Before you try out the solution, make sure that you have the following prerequisites in place, which are required by the Verified Permissions setup wizard:

  1. A Cognito user pool, along with Cognito groups that control authorization to the API endpoints.
  2. An API Gateway REST API in the same Region as the Cognito user pool.

As you review the resources generated by the solution, consider these authorization modeling topics:

  • Are access tokens or id tokens preferable for your API? Are there custom claims on your tokens that you would use in future Cedar policies for fine-grained authorization?
  • Do multiple authorizers fit your model, or do you have an “all users” group for use in Cedar policies?
  • How might you extend the Cedar schema, allowing for new Cedar policies that include URL path parameters, such as {petId} from the example?

Conclusion

This post demonstrated how the Amazon Verified Permissions setup wizard provides you with a step-by-step process to build authorization logic for API Gateway REST APIs using Cognito user groups. The wizard generates a policy store, schema, and Cedar policies to manage access to API endpoints based on the specification of the APIs deployed. In addition, the wizard creates a Lambda authorizer that authorizes access to the API Gateway resources based on the configured Cognito groups. This removes the modeling effort required for initial configuration of API authorization logic and setup of Verified Permissions to receive permission requests. You can use the wizard to set up and test access controls to your APIs based on Cognito groups in non-production accounts. You can further extend the policy schema and policies to accommodate fine-grained or attribute-based access controls, based on specific requirements of the application, without making code changes.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, start a new thread on the Amazon Verified Permissions re:Post or contact AWS Support.

Kevin Hakanson

Kevin Hakanson

Kevin is a Senior Solutions Architect for AWS World Wide Public Sector, based in Minnesota. He works with EdTech and GovTech customers to ideate, design, validate, and launch products using cloud-native technologies and modern development practices. When not staring at a computer screen, he is probably staring at another screen, either watching TV or playing video games with his family.

sowjir-1.jpeg

Sowjanya Rajavaram

Sowjanya is a Senior Solutions Architect who specializes in identity and security solutions at AWS. Her career has been focused on helping customers of all sizes solve their identity and access management problems. She enjoys traveling and experiencing new cultures and food.

Detecting and remediating inactive user accounts with Amazon Cognito

Post Syndicated from Harun Abdi original https://aws.amazon.com/blogs/security/detecting-and-remediating-inactive-user-accounts-with-amazon-cognito/

For businesses, particularly those in highly regulated industries, managing user accounts isn’t just a matter of security but also a compliance necessity. In sectors such as finance, healthcare, and government, where regulations often mandate strict control over user access, disabling stale user accounts is a key compliance activity. In this post, we show you a solution that uses serverless technologies to track and disable inactive user accounts. While this process is particularly relevant for those in regulated industries, it can also be beneficial for other organizations looking to maintain a clean and secure user base.

The solution focuses on identifying inactive user accounts in Amazon Cognito and automatically disabling them. Disabling a user account in Cognito effectively restricts the user’s access to applications and services linked with the Amazon Cognito user pool. After their account is disabled, the user cannot sign in, access tokens are revoked for their account and they are unable to perform API operations that require user authentication. However, the user’s data and profile within the Cognito user pool remain intact. If necessary, the account can be re-enabled, allowing the user to regain access and functionality.

While the solution focuses on the example of a single Amazon Cognito user pool in a single account, you also learn considerations for multi-user pool and multi-account strategies.

Solution overview

In this section, you learn how to configure an AWS Lambda function that captures the latest sign-in records of users authenticated by Amazon Cognito and write this data to an Amazon DynamoDB table. A time-to-live (TTL) indicator is set on each of these records based on the user inactivity threshold parameter defined when deploying the solution. This TTL represents the maximum period a user can go without signing in before their account is disabled. As these items reach their TTL expiry in DynamoDB, a second Lambda function is invoked to process the expired items and disable the corresponding user accounts in Cognito. For example, if the user inactivity threshold is configured to be 7 days, the accounts of users who don’t sign in within 7 days of their last sign-in will be disabled. Figure 1 shows an overview of the process.

Note: This solution functions as a background process and doesn’t disable user accounts in real time. This is because DynamoDB Time to Live (TTL) is designed for efficiency and to remain within the constraints of the Amazon Cognito quotas. Set your users’ and administrators’ expectations accordingly, acknowledging that there might be a delay in the reflection of changes and updates.

Figure 1: Architecture diagram for tracking user activity and disabling inactive Amazon Cognito users

Figure 1: Architecture diagram for tracking user activity and disabling inactive Amazon Cognito users

As shown in Figure 1, this process involves the following steps:

  1. An application user signs in by authenticating to Amazon Cognito.
  2. Upon successful user authentication, Cognito initiates a post authentication Lambda trigger invoking the PostAuthProcessorLambda function.
  3. The PostAuthProcessorLambda function puts an item in the LatestPostAuthRecordsDDB DynamoDB table with the following attributes:
    1. sub: A unique identifier for the authenticated user within the Amazon Cognito user pool.
    2. timestamp: The time of the user’s latest sign-in, formatted in UTC ISO standard.
    3. username: The authenticated user’s Cognito username.
    4. userpool_id: The identifier of the user pool to which the user authenticated.
    5. ttl: The TTL value, in seconds, after which a user’s inactivity will initiate account deactivation.
  4. Items in the LatestPostAuthRecordsDDB DynamoDB table are automatically purged upon reaching their TTL expiry, launching events in DynamoDB Streams.
  5. DynamoDB Streams events are filtered to allow invocation of the DDBStreamProcessorLambda function only for TTL deleted items.
  6. The DDBStreamProcessorLambda function runs to disable the corresponding user accounts in Cognito.

Implementation details

In this section, you’re guided through deploying the solution, demonstrating how to integrate it with your existing Amazon Cognito user pool and exploring the solution in more detail.

Note: This solution begins tracking user activity from the moment of its deployment. It can’t retroactively track or manage user activities that occurred prior to its implementation. To make sure the solution disables currently inactive users in the first TTL period after deploying the solution, you should do a one-time preload of those users into the DynamoDB table. If this isn’t done, the currently inactive users won’t be detected because users are detected as they sign in. For the same reason, users who create accounts but never sign in won’t be detected either. To detect user accounts that sign up but never sign in, implement a post confirmation Lambda trigger to invoke a Lambda function that processes user sign-up records and writes them to the DynamoDB table.

Prerequisites

Before deploying this solution, you must have the following prerequisites in place:

  • An existing Amazon Cognito user pool. This user pool is the foundation upon which the solution operates. If you don’t have a Cognito user pool set up, you must create one before proceeding. See Creating a user pool.
  • The ability to launch a CloudFormation template. The second prerequisite is the capability to launch an AWS CloudFormation template in your AWS environment. The template provisions the necessary AWS services, including Lambda functions, a DynamoDB table, and AWS Identity and Access Management (IAM) roles that are integral to the solution. The template simplifies the deployment process, allowing you to set up the entire solution with minimal manual configuration. You must have the necessary permissions in your AWS account to launch CloudFormation stacks and provision these services.

To deploy the solution

  1. Choose the following Launch Stack button to deploy the solution’s CloudFormation template:

    Launch Stack

    The solution deploys in the AWS US East (N. Virginia) Region (us-east-1) by default. To deploy the solution in a different Region, use the Region selector in the console navigation bar and make sure that the services required for this walkthrough are supported in your newly selected Region. For service availability by Region, see AWS Services by Region.

  2. On the Quick Create Stack screen, do the following:
    1. Specify the stack details.
      1. Stack name: The stack name is an identifier that helps you find a particular stack from a list of stacks. A stack name can contain only alphanumeric characters (case sensitive) and hyphens. It must start with an alphabetic character and can’t be longer than 128 characters.
      2. CognitoUserPoolARNs: A comma-separated list of Amazon Cognito user pool Amazon Resource Names (ARNs) to monitor for inactive users.
      3. UserInactiveThresholdDays: Time (in days) that the user account is allowed to be inactive before it’s disabled.
    2. Scroll to the bottom, and in the Capabilities section, select I acknowledge that AWS CloudFormation might create IAM resources with custom names.
    3. Choose Create Stack.

Integrate with your existing user pool

With the CloudFormation template deployed, you can set up Lambda triggers in your existing user pool. This is a key step for tracking user activity.

Note: This walkthrough is using the new AWS Management Console experience. Alternatively, These steps could also be done using CloudFormation.

To integrate with your existing user pool

  1. Navigate to the Amazon Cognito console and select your user pool.
  2. Navigate to User pool properties.
  3. Under Lambda triggers, choose Add Lambda trigger. Select the Authentication radio button, then add a Post authentication trigger and assign the PostAuthProcessorLambda function.

Note: Amazon Cognito allows you to set up one Lambda trigger per event. If you already have a configured post authentication Lambda trigger, you can refactor the existing Lambda function, adding new features directly to minimize the cold starts associated with invoking additional functions (for more information, see Anti-patterns in Lambda-based applications). Keep in mind that when Cognito calls your Lambda function, the function must respond within 5 seconds. If it doesn’t and if the call can be retried, Cognito retries the call. After three unsuccessful attempts, the function times out. You can’t change this 5-second timeout value.

Figure 2: Add a post-authentication Lambda trigger and assign a Lambda function

Figure 2: Add a post-authentication Lambda trigger and assign a Lambda function

When you add a Lambda trigger in the Amazon Cognito console, Cognito adds a resource-based policy to your function that permits your user pool to invoke the function. When you create a Lambda trigger outside of the Cognito console, including a cross-account function, you must add permissions to the resource-based policy of the Lambda function. Your added permissions must allow Cognito to invoke the function on behalf of your user pool. You can add permissions from the Lambda console or use the Lambda AddPermission API operation. To configure this in CloudFormation, you can use the AWS::Lambda::Permission resource.

Explore the solution

The solution should now be operational. It’s configured to begin monitoring user sign-in activities and automatically disable inactive user accounts according to the user inactivity threshold. Use the following procedures to test the solution:

Note: When testing the solution, you can set the UserInactiveThresholdDays CloudFormation parameter to 0. This minimizes the time it takes for user accounts to be disabled.

Step 1: User authentication

  1. Create a user account (if one doesn’t exist) in the Amazon Cognito user pool integrated with the solution.
  2. Authenticate to the Cognito user pool integrated with the solution.
     
    Figure 3: Example user signing in to the Amazon Cognito hosted UI

    Figure 3: Example user signing in to the Amazon Cognito hosted UI

Step 2: Verify the sign-in record in DynamoDB

Confirm the sign-in record was successfully put in the LatestPostAuthRecordsDDB DynamoDB table.

  1. Navigate to the DynamoDB console.
  2. Select the LatestPostAuthRecordsDDB table.
  3. Select Explore Table Items.
  4. Locate the sign-in record associated with your user.
     
Figure 4: Locating the sign-in record associated with the signed-in user

Figure 4: Locating the sign-in record associated with the signed-in user

Step 3: Confirm user deactivation in Amazon Cognito

After the TTL expires, validate that the user account is disabled in Amazon Cognito.

  1. Navigate to the Amazon Cognito console.
  2. Select the relevant Cognito user pool.
  3. Under Users, select the specific user.
  4. Verify the Account status in the User information section.
     
Figure 5: Screenshot of the user that signed in with their account status set to disabled

Figure 5: Screenshot of the user that signed in with their account status set to disabled

Note: TTL typically deletes expired items within a few days. Depending on the size and activity level of a table, the actual delete operation of an expired item can vary. TTL deletes items on a best effort basis, and deletion might take longer in some cases.

The user’s account is now disabled. A disabled user account can’t be used to sign in, but still appears in the responses to GetUser and ListUsers API requests.

Design considerations

In this section, you dive deeper into the key components of this solution.

DynamoDB schema configuration:

The DynamoDB schema has the Amazon Cognito sub attribute as the partition key. The Cognito sub is a globally unique user identifier within Cognito user pools that cannot be changed. This configuration ensures each user has a single entry in the table, even if the solution is configured to track multiple user pools. See Other considerations for more about tracking multiple user pools.

Using DynamoDB Streams and Lambda to disable TTL deleted users

This solution uses DynamoDB TTL and DynamoDB Streams alongside Lambda to process user sign-in records. The TTL feature automatically deletes items past their expiration time without write throughput consumption. The deleted items are captured by DynamoDB Streams and processed using Lambda. You also apply event filtering within the Lambda event source mapping, ensuring that the DDBStreamProcessorLambda function is invoked exclusively for TTL-deleted items (see the following code example for the JSON filter pattern). This approach reduces invocations of the Lambda functions, simplifies code, and reduces overall cost.

{
    "Filters": [
        {
            "Pattern": { "userIdentity": { "type": ["Service"], "principalId": ["dynamodb.amazonaws.com"] } }
        }
    ]
}

Handling API quotas:

The DDBStreamProcessorLambda function is configured to comply with the AdminDisableUser API’s quota limits. It processes messages in batches of 25, with a parallelization factor of 1. This makes sure that the solution remains within the nonadjustable 25 requests per second (RPS) limit for AdminDisableUser, avoiding potential API throttling. For more details on these limits, see Quotas in Amazon Cognito.

Dead-letter queues:

Throughout the architecture, dead-letter queues (DLQs) are used to handle message processing failures gracefully. They make sure that unprocessed records aren’t lost but instead are queued for further inspection and retry.

Other considerations

The following considerations are important for scaling the solution in complex environments and maintaining its integrity. The ability to scale and manage the increased complexity is crucial for successful adoption of the solution.

Multi-user pool and multi-account deployment

While this solution discussed a single Amazon Cognito user pool in a single AWS account, this solution can also function in environments with multiple user pools. This involves deploying the solution and integrating with each user pool as described in Integrating with your existing user pool. Because of the AdminDisableUser API’s quota limit for the maximum volume of requests in one AWS Region in one AWS account, consider deploying the solution separately in each Region in each AWS account to stay within the API limits.

Efficient processing with Amazon SQS:

Consider using Amazon Simple Queue Service (Amazon SQS) to add a queue between the PostAuthProcessorLambda function and the LatestPostAuthRecordsDDB DynamoDB table to optimize processing. This approach decouples user sign-in actions from DynamoDB writes, and allows for batching writes to DynamoDB, reducing the number of write requests.

Clean up

Avoid unwanted charges by cleaning up the resources you’ve created. To decommission the solution, follow these steps:

  1. Remove the Lambda trigger from the Amazon Cognito user pool:
    1. Navigate to the Amazon Cognito console.
    2. Select the user pool you have been working with.
    3. Go to the Triggers section within the user pool settings.
    4. Manually remove the association of the Lambda function with the user pool events.
  2. Remove the CloudFormation stack:
    1. Open the CloudFormation console.
    2. Locate and select the CloudFormation stack that was used to deploy the solution.
    3. Delete the stack.
    4. CloudFormation will automatically remove the resources created by this stack, including Lambda functions, Amazon SQS queues, and DynamoDB tables.

Conclusion

In this post, we walked you through a solution to identify and disable stale user accounts based on periods of inactivity. While the example focuses on a single Amazon Cognito user pool, the approach can be adapted for more complex environments with multiple user pools across multiple accounts. For examples of Amazon Cognito architectures, see the AWS Architecture Blog.

Proper planning is essential for seamless integration with your existing infrastructure. Carefully consider factors such as your security environment, compliance needs, and user pool configurations. You can modify this solution to suit your specific use case.

Maintaining clean and active user pools is an ongoing journey. Continue monitoring your systems, optimizing configurations, and keeping up-to-date on new features. Combined with well-architected preventive measures, automated user management systems provide strong defenses for your applications and data.

For further reading, see the AWS Well-Architected Security Pillar and more posts like this one on the AWS Security Blog.

If you have feedback about this post, submit comments in the Comments section. If you have questions about this post, start a new thread on the Amazon Cognito re:Post forum or contact AWS Support.

Harun Abdi

Harun Abdi

Harun is a Startup Solutions Architect based in Toronto, Canada. Harun loves working with customers across different sectors, supporting them to architect reliable and scalable solutions. In his spare time, he enjoys playing soccer and spending time with friends and family.

Dylan Souvage

Dylan Souvage

Dylan is a Partner Solutions Architect based in Austin, Texas. Dylan loves working with customers to understand their business needs and enable them in their cloud journey. In his spare time, he enjoys going out in nature and going on long road trips.

How to use OAuth 2.0 in Amazon Cognito: Learn about the different OAuth 2.0 grants

Post Syndicated from Prashob Krishnan original https://aws.amazon.com/blogs/security/how-to-use-oauth-2-0-in-amazon-cognito-learn-about-the-different-oauth-2-0-grants/

Implementing authentication and authorization mechanisms in modern applications can be challenging, especially when dealing with various client types and use cases. As developers, we often struggle to choose the right authentication flow to balance security, user experience, and application requirements. This is where understanding the OAuth 2.0 grant types comes into play. Whether you’re building a traditional web application, a mobile app, or a machine-to-machine communication system, understanding the OAuth 2.0 grant types can help you implement robust and secure authentication and authorization mechanism.

In this blog post, we show you the different OAuth 2.0 grants and how to implement them in Amazon Cognito. We review the purpose of each grant, their relevance in modern application development, and which grant is best suited for different application requirements.

OAuth 2.0 is an authorization framework that enables secure and seamless access to resources on behalf of users without the need to share sensitive credentials. The primary objective of OAuth 2.0 is to establish a secure, delegated, and scoped access mechanism that allows third-party applications to interact with user data while maintaining robust privacy and security measures.

OpenID Connect, often referred to as OIDC, is a protocol based on OAuth 2.0. It extends OAuth 2.0 to provide user authentication, identity verification, and user information retrieval. OIDC is a crucial component for building secure and user-friendly authentication experiences in applications. Amazon Cognito supports OIDC, meaning it supports user authentication and identity verification according to OIDC standards.

Amazon Cognito is an identity environment for web and mobile applications. Its two main components are user pools and identity pools. A Cognito user pool is a user directory, an authentication server, and an authorization service for OAuth 2.0 tokens. With it, you can authenticate and authorize users natively or from a federated identity such as your enterprise directory, or from consumer identity providers such as Google or Facebook. Cognito Identity Pool can exchange OAuth 2.0 tokens (among other options) for AWS credentials.

Implementing OAuth 2.0 grants using Amazon Cognito

The OAuth 2.0 standard defines four main roles; these are important to know as we discuss the grants:

  • A resource owner owns the data in the resource server and can grant access to the resource (such as a database admin).
  • A resource server hosts the protected resources that the application wants to access (such as a SQL server).
  • A client is an application making requests for the protected resources on behalf of the resource owner and with its authorization (such as an analytics application).
  • An authorization server is a server that issues scoped tokens after the user is authenticated and has consented to the issuance of the token under the desired scope (such as Amazon Cognito).

A few other useful concepts before we dive into the OAuth 2.0 grants:

  • Access tokens are at the core of OAuth 2.0’s operation. These tokens are short-lived credentials that the client application uses to prove its authorized status when requesting resources from the resource server. Additionally, OAuth 2.0 might involve the use of refresh tokens, which provide a mechanism for clients to obtain new access tokens without requiring the resource owner’s intervention.
  • An ID token is a JSON Web Token (JWT) introduced by OpenID Connect that contains information about the authentication event of the user. They allow applications to verify the identity of the user, make informed decisions about the user’s authentication status, and personalize the user’s experience.
  • A scope is a level of access that an application can request to a resource. Scopes define the specific permissions that a client application can request when obtaining an access token. You can use scopes to fine-tune the level of access granted to the client. For example, an OAuth 2.0 request might include the scope read:profile, indicating that the client application is requesting read-only access to the user’s profile information. Another request might include the scope write:photos, indicating the client’s need to write to the user’s photo collection. In Amazon Cognito, you can define custom scopes along with standard OAuth 2.0 scopes such as openid, profile, email, or phone to align with your application’s requirements. You can use this flexibility to manage access permissions efficiently and securely.

A typical high-level OAuth 2.0 flow looks like the Figure 1:

Figure 1: OAuth 2.0 flow

Figure 1: OAuth 2.0 flow

Below are the steps involved in the OAuth 2.0 flow

  1. The client requests authorization from the resource owner. This is done through the authorization server (Amazon Cognito) as an intermediary.
  2. The resource owner provides the authorization grant to the client. This can be one of the many grant types, which are discussed in detail in the next paragraph. The type of grant used depends on the method used by the client to request authorization from the resource owner.
  3. The client requests an access token by authenticating with Cognito.
  4. Cognito authenticates the client (the authentication method based on the grant type) and issues an access token if the authorization is valid.
  5. The access token is presented to the resource server as the client requests the protected resource.
  6. The resource server checks the access token’s signature and attributes and serves the request if it is valid.

There are several different grant types, four of which are described in the following sections.

Authorization code grant

The authorization code grant type is used by clients to securely exchange an authorization code for an access token. It’s used by both web applications and native applications to get an access token after a user authenticates to an application. After the user returns to the client through the redirect URI (the URL where the authentication server redirects the browser after it authorizes the user), the application gets the authorization code from the URL and uses it to request an access token.

This grant type is suitable for general cases as only one authentication flow is used, regardless of what operation is performed or who is performing it. This grant is considered secure as it requests an access token with a single-use code instead of exposing the actual access tokens. This helps prevent the application from potentially accessing user credentials.

Figure 2: Authorization code grant flow

Figure 2: Authorization code grant flow

Below are the steps involved in the authorization code grant flow

  1. The process begins with the client initiating the sequence, directing the user-agent (that is, the browser) of the resource owner to the authorization endpoint. In this action, the client provides its client identifier, the scope it’s requesting, a local state, and a redirection URI to which the authorization server (Amazon Cognito) will return the user agent after either granting or denying access.
  2. Cognito authenticates the resource owner (through the user agent) and establishes whether the resource owner grants or denies the client’s access request using user pool authentication.
  3. Cognito redirects the user agent back to the client using the redirection URI that was provided in step (1) with an authorization code in the query string (such as http://www.example.com/webpage?code=<authcode>).
  4. The client requests an access token from the Cognito’s token endpoint by including the authorization code received in step (3). When making the request, the client authenticates with the Cognito typically with a client ID and a secret. The client includes the redirection URI used to obtain the authorization code for verification.
  5. Cognito authenticates the client, validates the authorization code, and makes sure that the redirection URI received matches the URI used to redirect the client in step (3). If valid, Cognito responds with an access token.

An implementation of the authorization code grant using Amazon Cognito looks like the following:

  1. An application makes an HTTP GET request to _DOMAIN/oauth2/authorize, where AUTH_DOMAIN represents the user pool’s configured domain. This request includes the following query parameters:
    • response_type – Set to code for this grant type.
    • client_id – The ID for the desired user pool app client.
    • redirect_uri – The URL that a user is directed to after successful authentication.
    • state (optional but recommended) – A random value that’s used to prevent cross-site request forgery (CSRF) attacks.
    • scope (optional) – A space-separated list of scopes to request for the generated tokens. Note that:
      • An ID token is only generated if the openid scope is requested.
      • The phone, email, and profile scopes can only be requested if openid is also requested.
      • A vended access token can only be used to make user pool API calls if aws.cognito.signin.user.admin (user pool’s reserved API scope) is requested.
    • identity_provider (optional) – Indicates the provider that the end user should authenticate with.
    • idp_identifier (optional) – Same as identity_provider but doesn’t expose the provider’s real name.
    • nonce (optional) – A random value that you can add to the request. The nonce value that you provide is included in the ID token that Amazon Cognito issues. To guard against replay attacks, your app can inspect the nonce claim in the ID token and compare it to the one you generated. For more information about the nonce claim, see ID token validation in the OpenID Connect standard.
  2. A CSRF token is returned in a cookie. If an identity provider was specified in the request from step 1, the rest of this step is skipped. The user is automatically redirected to the appropriate identity provider’s authentication page. Otherwise, the user is redirected to https://AUTH_DOMAIN/login (which hosts the auto-generated UI) with the same query parameters set from step 1. They can then either authenticate with the user pool or select one of the third-party providers that’s configured for the designated app client.
  3. The user authenticates with their identity provider through one of the following means:
    1. If the user uses the native user pool to authenticate, the hosted UI submits the user’s credentials through a POST request to https://AUTH_DOMAIN/login (including the original query parameters) along with some additional metadata.
    2. If the user selects a different identity provider to authenticate with, the user is redirected to that identity provider’s authentication page. After successful authentication the provider redirects the user to https://AUTH_DOMAIN/saml2/idpresponse with either an authorization token in the code query parameter or a SAML assertion in a POST request.
  4. After Amazon Cognito verifies the user pool credentials or provider tokens it receives, the user is redirected to the URL that was specified in the original redirect_uri query parameter. The redirect also sets a code query parameter that specifies the authorization code that was vended to the user by Cognito.
  5. The custom application that’s hosted at the redirect URL can then extract the authorization code from the query parameters and exchange it for user pool tokens. The exchange occurs by submitting a POST request to https://AUTH_DOMAIN/oauth2/token with the following application/x-www-form-urlencoded parameters:
    • grant_type – Set to authorization_code for this grant.
    • code – The authorization code that’s vended to the user.
    • client_id – Same as from the request in step 1.
    • redirect_uri – Same as from the request in step 1.

If the client application that was configured with a secret, the Authorization header for this request is set as Basic BASE64(CLIENT_ID:CLIENT_SECRET), where BASE64(CLIENT_ID:CLIENT_SECRET) is the base64 representation of the application client ID and application client secret, concatenated with a colon.

The JSON returned in the resulting response has the following keys:

  • access_token – A valid user pool access token.
  • refresh_token – A valid user pool refresh token. This can be used to retrieve new tokens by sending it through a POST request to https://AUTH_DOMAIN/oauth2/token, specifying the refresh_token and client_id parameters, and setting the grant_type parameter to refresh_token.
  • id_token – A valid user pool ID token. Note that an ID token is only provided if the openid scope was requested.
  • expires_in – The length of time (in seconds) that the provided ID or access tokens are valid.
  • token_type – Set to Bearer.

Here are some of the best practices to be followed when using the authorization code grant:

  • Use the Proof Key for Code Exchange (PKCE) extension with the authorization code grant, especially for public clients such as a single page web application. This is discussed in more detail in the following section.
  • Regularly rotate client secrets and credentials to minimize the risk of unauthorized access.
  • Implement session management to handle user sessions securely. This involves managing access token lifetimes, storing tokens, rotating refresh tokens, implementing token revocations and providing easy logout mechanisms that invalidate access and refresh tokens on user’s devices.

Authorization code grant with PKCE

To enhance security when using the authorization code grant, especially in public clients such as native applications, the PKCE extension was introduced. PKCE adds an extra layer of protection by making sure that only the client that initiated the authorization process can exchange the received authorization code for an access token. This combination is sometimes referred to as a PKCE grant.

It introduces a secret called the code verifier, which is a random value created by the client for each authorization request. This value is then hashed using a transformation method such as SHA256—this is now called the code challenge. The same steps are followed as the flow from Figure 2, however the code challenge is now added to the query string for the request to the authorization server (Amazon Cognito). The authorization server stores this code challenge for verification after the authentication process and redirects back with an authorization code. This authorization code along with the code verifier is sent to the authorization server, which then compares the previously stored code challenge with the code verifier. Access tokens are issued after the verification is successfully completed. Figure 3 outlines this process.

Figure 3: Authorization code grant flow with PKCE

Figure 3: Authorization code grant flow with PKCE

Authorization code grant with PKCE implementation is identical to authorization code grant except that Step 1 requires two additional query parameters:

  • code_challenge – The hashed, base64 URL-encoded representation of a random code that’s generated client side (code verifier). It serves as a PKCE, which mitigates bad actors from being able to use intercepted authorization codes.
  • code_challenge_method – The hash algorithm that’s used to generate the code_challenge. Amazon Cognito currently only supports setting this parameter to S256. This indicates that the code_challenge parameter was generated using SHA-256.

In step 5, when exchanging the authorization code with the user pool token, include an additional parameter:

  • code_verifier – The base64 URL-encoded representation of the unhashed, random string that was used to generate the PKCE code_challenge in the original request.

Implicit grant (not recommended)

Implicit grant was an OAuth 2.0 authentication grant type that allowed clients such as single-page applications and mobile apps to obtain user access tokens directly from the authorization endpoint. The grant type was implicit because no intermediate credentials (such as an authorization code) were issued and later used to obtain an access token. The implicit grant has been deprecated and it’s recommended that you use authorization code grant with PKCE instead. An effect of using the implicit grant was that it exposed access tokens directly in the URL fragment, which could potentially be saved in the browser history, intercepted, or exposed to other applications residing on the same device.

Figure 4: Implicit grant flow

Figure 4: Implicit grant flow

The implicit grant flow was designed to enable public client-side applications—such as single-page applications or mobile apps without a backend server component—to exchange authorization codes for tokens.

Steps 1, 2, and 3 of the implicit grant are identical to the authorization code grant steps, except that the response_type query parameter is set to token. Additionally, while a PKCE challenge can technically be passed, it isn’t used because the /oauth2/token endpoint is never accessed. The subsequent steps—starting with step 4—are as follows:

  1. After Amazon Cognito verifies the user pool credentials or provider tokens it receives, the user is redirected to the URL that was specified in the original redirect_uri query parameter. The redirect also sets the following query parameters:
    • access_token – A valid user pool access token.
    • expires_in – The length of time (in seconds) that the provided ID or access tokens are valid for.
    • token_type – Set to Bearer.
    • id_token – A valid user pool ID token. Note that an ID token is only provided if the openid scope was requested.

    Note that no refresh token is returned during an implicit grant, as specified in the RFC standard.

  2. The custom application that’s hosted at the redirect URL can then extract the access token and ID token (if they’re present) from the query parameters.

Here are some best practices for implicit grant:

  • Make access token lifetimes short. Implicit grant tokens can’t be revoked, so expiry is the only way to end their validity.
  • Implicit grant type is deprecated and should be used only for scenarios where a backend server component can’t be implemented, such as browser-based applications.

Client credentials grant

The client credentials grant is for machine-to-machine authentication. For example, a third-party application must verify its identity before it can access your system. The client can request an access token using only its client credentials (or other supported means of authentication) when the client is requesting access to the protected resources under its control or those of another resource owner that have been previously arranged with the authorization server.

The client credentials grant type must be used only by confidential clients. This means the client must have the ability to protect a secret string from users. Note that to use the client credentials grant, the corresponding user pool app client must have an associated app client secret.

Figure 5: Client credentials grant

Figure 5: Client credentials grant

The flow illustrated in Figure 5 includes the following steps:

  1. The client authenticates with the authorization server using a client ID and secret and requests an access token from the token endpoint.
  2. The authorization server authenticates the client, and if valid, issues an access token.

The detailed steps for the process are as follows:

  1. The application makes a POST request to https://AUTH_DOMAIN/oauth2/token, and specifies the following parameters:
    • grant_type – Set to client_credentials for this grant type.
    • client_id – The ID for the desired user pool app client.
    • scope – A space-separated list of scopes to request for the generated access token. Note that you can only use a custom scope with the client credentials grant.

In order to indicate that the application is authorized to make the request, the Authorization header for this request is set as Basic BASE64(CLIENT_ID:CLIENT_SECRET), where BASE64(CLIENT_ID:CLIENT_SECRET) is the base64 representation of the client ID and client secret, concatenated with a colon.

The Amazon Cognito authorization server returns a JSON object with the following keys:

  • access_token – A valid user pool access token.
  • expires_in – The length of time (in seconds) that the provided access token is valid.
  • token_type – Set to Bearer.

Note that, for this grant type, an ID token and a refresh token aren’t returned.

  1. The application uses the access token to make requests to an associated resource server.
  2. The resource server validates the received token and, if everything checks out, processes the request from the app.

Following are a few recommended practices while using the client credentials grant:

  • Store client credentials securely and avoid hardcoding them in your application. Use appropriate credential management practices, such as environment variables or secret management services.
  • Limit use cases. The client credentials grant is suitable for machine-to-machine authentication in highly trusted scenarios. Limit its use to cases where other grant types are not applicable.

Extension grant

Extension grants are a way to add support for non-standard token issuance scenarios such as token translation, delegation, or custom credentials. It lets you exchange access tokens from a third-party OAuth 2.0 authorization service with access tokens from Amazon Cognito. By defining the grant type using an absolute URI (determined by the authorization server) as the value of the grant_type argument of the token endpoint, and by adding other parameters required, the client can use an extension grant type.

An example of an extension grant is OAuth 2.0 device authorization grant (RFC 8628). This authorization grant makes it possible for internet-connected devices with limited input capabilities or that lack a user-friendly browser (such as wearables, smart assistants, video-streaming devices, smart-home automation, and health or medical devices) to review the authorization request on a secondary device, such as a smartphone, that has more advanced input and browser capabilities.

Some of the best practices to be followed when deciding to use extension grants are:

  • Extension grants are for non-standard token issuance scenarios. Use them only when necessary, and thoroughly document their use and purpose.
  • Conduct security audits and code reviews when implementing Extension grants to identify potential vulnerabilities and mitigate risks.

While Amazon Cognito doesn’t natively support extension grants currently, here is an example implementation of OAuth 2.0 device grant flow using AWS Lambda and Amazon DynamoDB.

Conclusion

In this blog post, we’ve reviewed various OAuth 2.0 grants, each catering to specific application needs, The authorization code grant ensures secure access for web applications (and offers additional security with the PKCE extension), and the client credentials grant is ideal for machine-to-machine authentication. Amazon Cognito acts as an encompassing identity platform, streamlining user authentication, authorization, and integration. By using these grants and the features provided by Cognito, developers can enhance security and the user experience in their applications. For more information and examples, see OAuth 2.0 grants in the Cognito Developer Guide.

Now that you understand implementing OAuth 2.0 grants in Amazon Cognito, see How to customize access tokens in Amazon Cognito user pools to learn about customizing access tokens to make fine-grained authorization decisions and provide a differentiated end-user experience.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, contact AWS Support.

Prashob Krishnan

Prashob Krishnan

Prashob is a Denver-based Technical Account Manager at AWS. Prashob is passionate about security. He enjoys working with customers to solve their technical challenges and help build a secure scalable architecture on the AWS Cloud.

Ishva Kanani

Ishva Kanani

Ishva is an Associate Security Consultant based in Fairfax, Virginia. She has a strong interest in security and enjoys assisting customers with securing cloud migrations and accelerating their journeys to the cloud and within the cloud ecosystem by delivering innovative solutions.

Keerthana Ganesh

Keerthana Ganesh

Keerthana is a Security and Compliance Solutions Architect at AWS based in the UK. She works with customers in EMEA and plays an advisory role on how to build secure architectures.

How to customize access tokens in Amazon Cognito user pools

Post Syndicated from Edward Sun original https://aws.amazon.com/blogs/security/how-to-customize-access-tokens-in-amazon-cognito-user-pools/

With Amazon Cognito, you can implement customer identity and access management (CIAM) into your web and mobile applications. You can add user authentication and access control to your applications in minutes.

In this post, I introduce you to the new access token customization feature for Amazon Cognito user pools and show you how to use it. Access token customization is included in the advanced security features (ASF) of Amazon Cognito. Note that ASF is subject to additional pricing as described on the Amazon Cognito pricing page.

What is access token customization?

When a user signs in to your app, Amazon Cognito verifies their sign-in information, and if the user is authenticated successfully, returns the ID, access, and refresh tokens. The access token, which uses the JSON Web Token (JWT) format following the RFC7519 standard, contains claims in the token payload that identify the principal being authenticated, and session attributes such as authentication time and token expiration time. More importantly, the access token also contains authorization attributes in the form of user group memberships and OAuth scopes. Your applications or API resource servers can evaluate the token claims to authorize specific actions on behalf of users.

With access token customization, you can add application-specific claims to the standard access token and then make fine-grained authorization decisions to provide a differentiated end-user experience. You can refine the original scope claims to further restrict access to your resources and enforce the least privileged access. You can also enrich access tokens with claims from other sources, such as user subscription information stored in an Amazon DynamoDB table. Your application can use this enriched claim to determine the level of access and content available to the user. This reduces the need to build a custom solution to look up attributes in your application’s code, thereby reducing application complexity, improving performance, and smoothing the integration experience with downstream applications.

How do I use the access token customization feature?

Amazon Cognito works with AWS Lambda functions to modify your user pool’s authentication behavior and end-user experience. In this section, you’ll learn how to configure a pre token generation Lambda trigger function and invoke it during the Amazon Cognito authentication process. I’ll also show you an example function to help you write your own Lambda function.

Lambda trigger flow

During a user authentication, you can choose to have Amazon Cognito invoke a pre token generation trigger to enrich and customize your tokens.

Figure 1: Pre token generation trigger flow

Figure 1: Pre token generation trigger flow

Figure 1 illustrates the pre token generation trigger flow. This flow has the following steps:

  1. An end user signs in to your app and authenticates with an Amazon Cognito user pool.
  2. After the user completes the authentication, Amazon Cognito invokes the pre token generation Lambda trigger, and sends event data to your Lambda function, such as userAttributes and scopes, in a pre token generation trigger event.
  3. Your Lambda function code processes token enrichment logic, and returns a response event to Amazon Cognito to indicate the claims that you want to add or suppress.
  4. Amazon Cognito vends a customized JWT to your application.

The pre token generation trigger flow supports OAuth 2.0 grant types, such as the authorization code grant flow and implicit grant flow, and also supports user authentication through the AWS SDK.

Enable access token customization

Your Amazon Cognito user pool delivers two different versions of the pre token generation trigger event to your Lambda function. Trigger event version 1 includes userAttributes, groupConfiguration, and clientMetadata in the event request, which you can use to customize ID token claims. Trigger event version 2 adds scope in the event request, which you can use to customize scopes in the access token in addition to customizing other claims.

In this section, I’ll show you how to update your user pool to trigger event version 2 and enable access token customization.

To enable access token customization

  1. Open the Cognito user pool console, and then choose User pools.
  2. Choose the target user pool for token customization.
  3. On the User pool properties tab, in the Lambda triggers section, choose Add Lambda trigger.
  4. Figure 2: Add Lambda trigger

    Figure 2: Add Lambda trigger

  5. In the Lambda triggers section, do the following:
    1. For Trigger type, select Authentication.
    2. For Authentication, select Pre token generation trigger.
    3. For Trigger event version, select Basic features + access token customization – Recommended. If this option isn’t available to you, make sure that you have enabled advanced security features. You must have advanced security features enabled to access this option.
  6. Figure 3: Select Lambda trigger

    Figure 3: Select Lambda trigger

  7. Select your Lambda function and assign it as the pre token generation trigger. Then choose Add Lambda trigger.
  8. Figure 4: Add Lambda trigger

    Figure 4: Add Lambda trigger

Example pre token generation trigger

Now that you have enabled access token customization, I’ll walk you through a code example of the pre token generation Lambda trigger, and the version 2 trigger event. This code example examines the trigger event request, and adds a new custom claim and a custom OAuth scope in the response for Amazon Cognito to customize the access token to suit various authorization scheme.

Here is an example version 2 trigger event. The event request contains the user attributes from the Amazon Cognito user pool, the original scope claims, and the original group configurations. It has two custom attributes—membership and location—which are collected during the user registration process and stored in the Cognito user pool.

{
  "version": "2",
  "triggerSource": "TokenGeneration_HostedAuth",
  "region": "us-east-1",
  "userPoolId": "us-east-1_01EXAMPLE",
  "userName": "mytestuser",
  "callerContext": {
    "awsSdkVersion": "aws-sdk-unknown-unknown",
    "clientId": "1example23456789"
  },
  "request": {
    "userAttributes": {
      "sub": "a1b2c3d4-5678-90ab-cdef-EXAMPLE11111",
      "cognito:user_status": "CONFIRMED",
      "email": "[email protected]",
      "email_verified": "true",
      "custom:membership": "Premium",
      "custom:location": "USA"
    },
    "groupConfiguration": {
      "groupsToOverride": [],
      "iamRolesToOverride": [],
      "preferredRole": null
    },
    "scopes": [
      "openid",
      "profile",
      "email"
    ]
  },
  "response": {
    "claimsAndScopeOverrideDetails": null
  }
}

In the following code example, I transformed the user’s location attribute and membership attribute to add a custom claim and a custom scope. I used the claimsToAddOrOverride field to create a new custom claim called demo:membershipLevel with a membership value of Premium from the event request. I also constructed a new scope with the value of membership:USA.Premium through the scopesToAdd claim, and added the new claim and scope in the event response.

export const handler = function(event, context) {
  // Retrieve user attribute from event request
  const userAttributes = event.request.userAttributes;
  // Add scope to event response
  event.response = {
    "claimsAndScopeOverrideDetails": {
      "idTokenGeneration": {},
      "accessTokenGeneration": {
        "claimsToAddOrOverride": {
          "demo:membershipLevel": userAttributes['custom:membership']
        },
        "scopesToAdd": ["membership:" + userAttributes['custom:location'] + "." + userAttributes['custom:membership']]
      }
    }
  };
  // Return to Amazon Cognito
  context.done(null, event);
};

With the preceding code, the Lambda trigger sends the following response back to Amazon Cognito to indicate the customization that was needed for the access tokens.

"response": {
  "claimsAndScopeOverrideDetails": {
    "idTokenGeneration": {},
    "accessTokenGeneration": {
      "claimsToAddOrOverride": {
        "demo:membershipLevel": "Premium"
      },
      "scopesToAdd": [
        "membership:USA.Premium"
      ]
    }
  }
}

Then Amazon Cognito issues tokens with these customizations at runtime:

{
  "sub": "a1b2c3d4-5678-90ab-cdef-EXAMPLE11111",
  "iss": "https://cognito-idp.us-east-1.amazonaws.com/us-east-1_01EXAMPLE",
  "version": 2,
  "client_id": "1example23456789",
  "event_id": "01faa385-562d-4730-8c3b-458e5c8f537b",
  "token_use": "access",
  "demo:membershipLevel": "Premium",
  "scope": "openid profile email membership:USA.Premium",
  "auth_time": 1702270800,
  "exp": 1702271100,
  "iat": 1702270800,
  "jti": "d903dcdf-8c73-45e3-bf44-51bf7c395e06",
  "username": "mytestuser"
}

Your application can then use the newly-minted, custom scope and claim to authorize users and provide them with a personalized experience.

Considerations and best practices

There are four general considerations and best practices that you can follow:

  1. Some claims and scopes aren’t customizable. For example, you can’t customize claims such as auth_time, iss, and sub, or scopes such as aws.cognito.signin.user.admin. For the full list of excluded claims and scopes, see the Excluded claims and scopes.
  2. Work backwards from authorization. When you customize access tokens, you should start with your existing authorization schema and then decide whether to customize the scopes or claims, or both. Standard OAuth based authorization scenarios, such as Amazon API Gateway authorizers, typically use custom scopes to provide access. However, if you have complex or fine-grained authorization requirements, then you should consider using both scopes and custom claims to pass additional contextual data to the application or to a policy-based access control service such as Amazon Verified Permission.
  3. Establish governance in token customization. You should have a consistent company engineering policy to provide nomenclature guidance for scopes and claims. A syntax standard promotes globally unique variables and avoids a name collision across different application teams. For example, Application X at AnyCompany can choose to name their scope as ac.appx.claim_name, where ac represents AnyCompany as a global identifier and appx.claim_name represents Application X’s custom claim.
  4. Be aware of limits. Because tokens are passed through various networks and systems, you need to be aware of potential token size limitations in your systems. You should keep scope and claim names as short as possible, while still being descriptive.

Conclusion

In this post, you learned how to integrate a pre token generation Lambda trigger with your Amazon Cognito user pool to customize access tokens. You can use the access token customization feature to provide differentiated services to your end users based on claims and OAuth scopes. For more information, see pre token generation Lambda trigger in the Amazon Cognito Developer Guide.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, contact AWS Support.

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Edward Sun

Edward Sun

Edward is a Security Specialist Solutions Architect focused on identity and access management. He loves helping customers throughout their cloud transformation journey with architecture design, security best practices, migration, and cost optimizations. Outside of work, Edward enjoys hiking, golfing, and cheering for his alma mater, the Georgia Bulldogs.

Converting stateful application to stateless using AWS services

Post Syndicated from Sarat Para original https://aws.amazon.com/blogs/architecture/converting-stateful-application-to-stateless-using-aws-services/

Designing a system to be either stateful or stateless is an important choice with tradeoffs regarding its performance and scalability. In a stateful system, data from one session is carried over to the next. A stateless system doesn’t preserve data between sessions and depends on external entities such as databases or cache to manage state.

Stateful and stateless architectures are both widely adopted.

  • Stateful applications are typically simple to deploy. Stateful applications save client session data on the server, allowing for faster processing and improved performance. Stateful applications excel in predictable workloads and offer consistent user experiences.
  • Stateless architectures typically align with the demands of dynamic workload and changing business requirements. Stateless application design can increase flexibility with horizontal scaling and dynamic deployment. This flexibility helps applications handle sudden spikes in traffic, maintain resilience to failures, and optimize cost.

Figure 1 provides a conceptual comparison of stateful and stateless architectures.

Conceptual diagram for stateful vs stateless architectures

Figure 1. Conceptual diagram for stateful vs stateless architectures

For example, an eCommerce application accessible from web and mobile devices manages several aspects of the customer transaction life cycle. This lifecycle starts with account creation, then moves to placing items in the shopping cart, and proceeds through checkout. Session and user profile data provide session persistence and cart management, which retain the cart’s contents and render the latest updated cart from any device. A stateless architecture is preferable for this application because it decouples user data and offloads the session data. This provides the flexibility to scale each component independently to meet varying workloads and optimize resource utilization.

In this blog, we outline the process and benefits of converting from a stateful to stateless architecture.

Solution overview

This section walks you through the steps for converting stateful to stateless architecture:

  1. Identifying and understanding the stateful requirements
  2. Decoupling user profile data
  3. Offloading session data
  4. Scaling each component dynamically
  5. Designing a stateless architecture

Step 1: Identifying and understanding the stateful components

Transforming a stateful architecture to a stateless architecture starts with reviewing the overall architecture and source code of the application, and then analyzing dataflow and dependencies.

Review the architecture and source code

It’s important to understand how your application accesses and shares  data. Pay attention to components that persist state data and retain state information. Examples include user credentials, user profiles, session tokens, and data specific to sessions (such as shopping carts). Identifying how this data is handled serves as the foundation for planning the conversion to a stateless architecture.

Analyze dataflow and dependencies

Analyze and understand the components that maintain state within the architecture. This helps you assess the potential impact of transitioning to a stateless design.

You can use the following questionnaire to assess the components. Customize the questions according to your application.

  • What data is specific to a user or session?
  • How is user data stored and managed?
  • How is the session data accessed and updated?
  • Which components rely on the user and session data?
  • Are there any shared or centralized data stores?
  • How does the state affect scalability and tolerance?
  • Can the stateful components be decoupled or made stateless?

Step 2: Decoupling user profile data

Decoupling user data involves separating and managing user data from the core application logic. Delegate responsibilities for user management and secrets, such as application programming interface (API) keys and database credentials, to a separate service that can be resilient and scale independently. For example, you can use:

  • Amazon Cognito to decouple user data from application code by using features, such as identity pools, user pools, and Amazon Cognito Sync.
  • AWS Secrets Manager to decouple user data by storing secrets in a secure, centralized location. This means that the application code doesn’t need to store secrets, which makes it more secure.
  • Amazon S3 to store large, unstructured data, such as images and documents. Your application can retrieve this data when required, eliminating the need to store it in memory.
  • Amazon DynamoDB to store information such as user profiles. Your application can query this data in near-real time.

Step 3: Offloading session data

Offloading session data refers to the practice of storing and managing session related data external to the stateful components of an application. This involves separating the state from business logic. You can offload session data to a database, cache, or external files.

Factors to consider when offloading session data include:

  • Amount of session data
  • Frequency and latency
  • Security requirements

Amazon ElastiCache, Amazon DynamoDB, Amazon Elastic File System (Amazon EFS), and Amazon MemoryDB for Redis are examples of AWS services that you can use to offload session data. The AWS service you choose for offloading session data depends on application requirements.

Step 4: Scaling each component dynamically

Stateless architecture gives the flexibility to scale each component independently, allowing the application to meet varying workloads and optimize resource utilization. While planning for scaling, consider using:

Step 5: Design a stateless architecture

After you identify which state and user data need to be persisted, and your storage solution of choice, you can begin designing the stateless architecture. This involves:

  • Understanding how the application interacts with the storage solution.
  • Planning how session creation, retrieval, and expiration logic work with the overall session management.
  • Refactoring application logic to remove references to the state information that’s stored on the server.
  • Rearchitecting the application into smaller, independent services, as described in steps 2, 3, and 4.
  • Performing thorough testing to ensure that all functionalities produce the desired results after the conversion.

The following figure is an example of a stateless architecture on AWS. This architecture separates the user interface, application logic, and data storage into distinct layers, allowing for scalability, modularity, and flexibility in designing and deploying applications. The tiers interact through well-defined interfaces and APIs, ensuring that each component focuses on its specific responsibilities.

Example of a stateless architecture

Figure 2. Example of a stateless architecture

Benefits

Benefits of adopting a stateless architecture include:

  • Scalability:  Stateless components don’t maintain a local state. Typically, you can easily replicate and distribute them to handle increasing workloads. This supports horizontal scaling, making it possible to add or remove capacity based on fluctuating traffic and demand.
  • Reliability and fault tolerance: Stateless architectures are inherently resilient to failures. If a stateless component fails, it can be replaced or restarted without affecting the overall system. Because stateless applications don’t have a shared state, failures in one component don’t impact other components. This helps ensure continuity of user sessions, minimizes disruptions, and improves fault tolerance and overall system reliability.
  • Cost-effectiveness: By leveraging on-demand scaling capabilities, your application can dynamically adjust resources based on actual demand, avoiding overprovisioning of infrastructure. Stateless architectures lend themselves to serverless computing models, paying for the actual run time and resulting in cost savings.
  • Performance: Externalizing session data by using services optimized for high-speed access, such as in-memory caches, can reduce the latency compared to maintaining session data internally.
  • Flexibility and extensibility: Stateless architectures provide flexibility and agility in application development. Offloaded session data provides more flexibility to adopt different technologies and services within the architecture. Applications can easily integrate with other AWS services for enhanced functionality, such as analytics, near real-time notifications, or personalization.

Conclusion

Converting stateful applications to stateless applications requires careful planning, design, and implementation. Your choice of architecture depends on your application’s specific needs. If an application is simple to develop and debug, then a stateful architecture might be a good choice. However, if an application needs to be scalable and fault tolerant, then a stateless architecture might be a better choice. It’s important to understand the current application thoroughly before embarking on a refactoring journey.

Further reading

Use private key JWT authentication between Amazon Cognito user pools and an OIDC IdP

Post Syndicated from Martin Pagel original https://aws.amazon.com/blogs/security/use-private-key-jwt-authentication-between-amazon-cognito-user-pools-and-an-oidc-idp/

With Amazon Cognito user pools, you can add user sign-up and sign-in features and control access to your web and mobile applications. You can enable your users who already have accounts with other identity providers (IdPs) to skip the sign-up step and sign in to your application by using an existing account through SAML 2.0 or OpenID Connect (OIDC). In this blog post, you will learn how to extend the authorization code grant between Cognito and an external OIDC IdP with private key JSON Web Token (JWT) client authentication.

For OIDC, Cognito uses the OAuth 2.0 authorization code grant flow as defined by the IETF in RFC 6749 Section 1.3.1. This flow can be broken down into two steps: user authentication and token request. When a user needs to authenticate through an external IdP, the Cognito user pool forwards the user to the IdP’s login endpoint. After successful authentication, the IdP sends back a response that includes an authorization code, which concludes the authentication step. The Cognito user pool now uses this code, together with a client secret for client authentication, to retrieve a JWT from the IdP. The JWT consists of an access token and an identity token. Cognito ingests that JWT, creates or updates the user in the user pool, and returns a JWT it has created for the client’s session, to the client. You can find a more detailed description of this flow in the Amazon Cognito documentation.

Although this flow sufficiently secures the requests between Cognito and the IdP for most customers, those in the public sector, healthcare, and finance sometimes need to integrate with IdPs that enforce additional security measures as part of their security requirements. In the past, this has come up in conversations at AWS when our customers needed to integrate Cognito with, for example, the HelseID (healthcare sector, Norway), login.gov (public sector, USA), or GOV.UK One Login (public sector, UK) IdPs. Customers who are using Okta, PingFederate, or similar IdPs and want additional security measures as part of their internal security requirements, might also find adding further security requirements desirable as part of their own policies.

The most common additional requirement is to replace the client secret with an assertion that consists of a private key JWT as a means of client authentication during token requests. This method is defined through a combination of RFC 7521 and RFC 7523. Instead of a symmetric key (the client secret), this method uses an asymmetric key-pair to sign a JWT with a private key. The IdP can then verify the token request by validating the signature of that JWT using the corresponding public key. This helps to eliminate the exposure of the client secret with every request, thereby reducing the risk of request forgery, depending on the quality of the key material that was used and how access to the private key is secured. Additionally, the JWT has an expiry time, which further constrains the risk of replay attacks to a narrow time window.

A Cognito user pool does not natively support private key JWT client authentication when integrating with an external IdP. However, you can still integrate Cognito user pools with IdPs that support or require private key JWT authentication by using Amazon API Gateway and AWS Lambda.

This blog post presents a high-level overview of how you can implement this solution. To learn more about the underlying code, how to configure the included services, and what the detailed request flow looks like, check out the Deploy a demo section later in this post. Keep in mind that this solution does not cover the request flow between your own application and a Cognito user pool, but only the communication between Cognito and the IdP.

Solution overview

Following the technical implementation details of the previously mentioned RFCs, the required request flow between a Cognito user pool and the external OIDC IdP can be broken down into four simplified steps, shown in Figure 1.

Figure 1: Simplified UML diagram of the target implementation for using a private key JWT during the authorization code grant

Figure 1: Simplified UML diagram of the target implementation for using a private key JWT during the authorization code grant

In this example, we’re using the Cognito user pool hosted UI—because it already provides OAuth 2.0-aligned IdP integration—and extending it with the private key JWT. Figure 1 illustrates the following steps:

  1. The hosted UI forwards the user client to the /authorize endpoint of the external OIDC IdP with an HTTP GET request.
  2. After the user successfully logs into the IdP, the IdP‘s response includes an authorization code.
  3. The hosted UI sends this code in an HTTP POST request to the IdP’s /token endpoint. By default, the hosted UI also adds a client secret for client authentication. To align with the private key JWT authentication method, you need to replace the client secret with a client assertion and specify the client assertion type, as highlighted in the diagram and further described later.
  4. The IdP validates the client assertion by using a pre-shared public key.
  5. The IdP issues the user’s JWT, which Cognito ingests to create or update the user in the user pool.

As mentioned earlier, token requests between a Cognito user pool and an external IdP do not natively support the required client assertion. However, you can redirect the token requests to, for example, an Amazon API Gateway, which invokes a Lambda function to extend the request with the new parameters. Because you need to sign the client assertion with a private key, you also need a secure location to store this key. For this, you can use AWS Secrets Manager, which helps you to secure the key from unauthorized use. With the required flow and additional services in mind, you can create the following architecture.

Figure 2: Architecture diagram with Amazon API Gateway and Lambda to process token requests between Cognito and the OIDC identity provider

Figure 2: Architecture diagram with Amazon API Gateway and Lambda to process token requests between Cognito and the OIDC identity provider

Let’s have a closer look at the individual components and the request flow that are shown in Figure 2.

When adding an OIDC IdP to a Cognito user pool, you configure endpoints for Authorization, UserInfo, Jwks_uri, and Token. Because the private key is required only for the token request flow, you can configure resources to redirect and process requests, as follows (the step numbers correspond to the step numbering in Figure 2):

  1. Configure the endpoints for Authorization, UserInfo, and Jwks_Uri with the ones from the IdP.
  2. Create an API Gateway with a dedicated route for token requests (for example, /token) and add it as the Token endpoint in the IdP configuration in Cognito.
  3. Integrate this route with a Lambda function: When Cognito calls the API endpoint, it will automatically invoke the function.

Together with the original request parameters, which include the authorization code, this function does the following:

  1. Retrieves the private key from Secrets Manager.
  2. Creates and signs the client assertion.
  3. Makes the token request to the IdP token endpoint.
  4. Receives the response from the IdP.
  5. Returns the response to the Cognito IdP response endpoint.

The details of the function logic can be broken down into the following:

  • Decode the body of the original request—this includes the authorization code that was acquired during the authorize flow.
    import base64
    
    encoded_message = event["body"]
    decoded_message = base64.b64decode(encoded_message)
    decoded_message = decoded_message.decode("utf-8")
    

  • Retrieve the private key from Secrets Manager by using the GetSecretValue API or SDK equivalent or by using the AWS Parameters and Secrets Lambda Extension.
  • Create and sign the JWT.
    import jwt # third party library – requires a Lambda Layer
    import time
    
    instance = jwt.JWT()
    private_key_jwt = instance.encode({
        "iss": <Issuer. Contains IdP client ID>,
        "sub": <Subject. Contains IdP client ID>,
        "aud": <Audience. IdP token endpoint>,
        "iat": int(time.time()),
        "exp": int(time.time()) + 300
    },
        {<YOUR RETRIEVED PRIVATE KEY IN JWK FORMAT>},
        alg='RS256',
        optional_headers = {"kid": private_key_dict["kid"]}
    )
    

  • Modify the original body and make the token request, including the original parameters for grant_type, code, and client_id, with added client_assertion_type and the client_assertion. (The following example HTTP request has line breaks and placeholders in angle brackets for better readability.)
    POST /token HTTP/1.1
      Scheme: https
      Host: your-idp.example.com
      Content-Type: application/x-www-form-urlencoded
    
      grant_type=authorization_code&
        code=<the authorization code>&
        client_id=<IdP client ID>&
        client_assertion_type=
        urn%3Aietf%3Aparams%3Aoauth%3Aclient-assertion-type%3Ajwt-bearer&
        client_assertion=<signed JWT>
    

  • Return the IdP’ s response.

Note that there is no client secret needed in this request. Instead, you add a client assertion type as urn:ietf:params:oauth:client-assertion-type:jwt-bearer, and the client assertion with the signed JWT.

If the request is successful, the IdP’s response includes a JWT with the access token and identity token. On returning the response via the Lambda function, Cognito ingests the JWT and creates or updates the user in the user pool. It then responds to the original authorize request of the user client by sending its own authorization code, which can be exchanged for a Cognito issued JWT in your own application.

Deploy a demo

To deploy an example of this solution, see our GitHub repository. You will find the prerequisites and deployment steps there, as well as additional in-depth information.

Additional considerations

To further optimize this solution, you should consider checking the event details in the Lambda function before fully processing the requests. This way, you can, for example, check that all required parameters are present and valid. One option to do that, is to define a client secret when you create the IdP integration for the user pool. When Cognito sends the token request, it adds the client secret in the encoded body, so you can retrieve it and validate its value. If the validation fails, requests can be dropped early to improve exception handling and to prevent invalid requests from causing unnecessary function charges.

In this example, we used Secrets Manager to store the private key. You can explore other alternatives, like AWS Systems Manager Parameter Store or AWS Key Management Service (AWS KMS). To retrieve the key from the Parameter Store, you can use the SDK or the AWS Parameter and Secrets Lambda Extension. With AWS KMS, you can both create and store the private key as well as derive a public key through the service’s APIs, and you can also use the signing API to sign the JWT in the Lambda function.

Conclusion

By redirecting the IdP token endpoint in the Cognito user pool’s external OIDC IdP configuration to a route in an API Gateway, you can use Lambda functions to customize the request flow between Cognito and the IdP. In the example in this post, we showed how to change the client authentication mechanism during the token request from a client secret to a client assertion with a signed JWT (private key JWT). You can also apply the same proxy-like approach to customize the request flow even further—for example, by adding a Proof Key for Code Exchange (PKCE), for which you can find an example in the aws-samples GitHub repository.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, start a new thread on AWS re:Post for Amazon Cognito User Pools or contact AWS Support.

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Martin Pagel

Martin Pagel

Martin is a Solutions Architect in Norway who specializes in security and compliance, with a focus on identity. Before joining AWS, he walked in the shoes of a systems administrator and engineer, designing and implementing the technical side of a wide variety of compliance controls at companies in automotive, fintech, and healthcare. Today, he helps our customers across the Nordic region to achieve their security and compliance objectives.

Approaches for migrating users to Amazon Cognito user pools

Post Syndicated from Edward Sun original https://aws.amazon.com/blogs/security/approaches-for-migrating-users-to-amazon-cognito-user-pools/

Update: An earlier version of this post was published on September 14, 2017, on the Front-End Web and Mobile Blog.


Amazon Cognito user pools offer a fully managed OpenID Connect (OIDC) identity provider so you can quickly add authentication and control access to your mobile app or web application. User pools scale to millions of users and add layers of additional features for security, identity federation, app integration, and customization of the user experience. Amazon Cognito is available in regions around the globe, processing over 100 billion authentications each month. You can take advantage of security features when using user pools in Cognito, such as email and phone number verification, multi-factor authentication, and advanced security features, such as compromised credentials detection, and adaptive authentications.

Many customers ask about the best way to migrate their existing users to Amazon Cognito user pools. In this blog post, we describe several different recommended approaches and provide step-by-step instructions on how to implement them.

Key considerations

The main consideration when migrating users across identity providers is maintaining a consistent end-user experience. Ideally, users can continue to use their existing passwords so that their experience is seamless. However, security best practices dictate that passwords should never be stored directly as cleartext in a user store. Instead, passwords are used to compute cryptographic hashes and verifiers that can later be used to verify submitted passwords. This means that you cannot securely export passwords in cleartext form from an existing user store and import them into a Cognito user pool. You might ask your users to choose a new password during the migration. Or, if you want to retain the existing passwords, you need to retain access to the existing hashes and verifiers, at least during the migration period.

A secondary consideration is the migration timeline. For example, do you need a faster migration timeline because your current identity store’s license is expiring? Or do you prefer a slow and steady migration because you are modernizing your current application, and it takes time to connect your existing systems to the new identity provider?

The following two methods define our recommended approaches for migrating existing users into a user pool:

  • Bulk user import – Export your existing users into a comma-separated (.csv) file, and then upload this .csv file to import users into a user pool. Your desired user attributes (except passwords) can be included and mapped to attributes in the target user pool. This approach requires users to reset their passwords when they sign in with Cognito. You can choose to migrate your existing user store entirely in a single import job or split users into multiple jobs for parallel or incremental processing.
  • Just-in-time user migration – Migrate users just in time into a Cognito user pool as they sign in to your mobile or web app. This approach allows users to retain their current passwords, because the migration process captures and verifies the password during the sign-in process, seamlessly migrating them to the Cognito user pool.

In the following sections, we describe the bulk user import and just-in-time user migration methods in more detail and then walk through the steps of each approach.

Bulk user import

You perform bulk import of users into an Amazon Cognito user pool by uploading a .csv file that contains user profile data, including usernames, email addresses, phone numbers, and other attributes. You can download a template .csv file for your user pool from Cognito, with a user schema structured in the template header.

Following is an example of performing bulk user import.

To create an import job

  1. Open the Cognito user pool console and select the target user pool for migration.
  2. On the Users tab, navigate to the Import users section, and choose Create import job.
  3. Figure 1: Create import job

    Figure 1: Create import job

  4. In the Create import job dialog box, download the template.csv file for user import.
  5. Export your existing user data from your existing user directory or store your data into the .csv file
  6. Match the user attribute types with column headings in the template. Each user must have an email address or a phone number that is marked as verified in the .csv file, in order to receive the password reset confirmation code.
  7. Figure 2: Configure import job

    Figure 2: Configure import job

  8. Go back to the Create import job dialog box (as shown in Figure 2) and do the following:
    1. Enter a Job name.
    2. Choose to Create a new IAM role or Use an existing IAM role. This role grants Amazon Cognito permission to write to Amazon CloudWatch Logs in your account, so that Cognito can provide logs for successful imports and errors for skipped or failed transactions.
    3. Upload the .csv file that you have prepared, and choose Create and start job.

Depending on the size of the .csv file, the job can run for minutes or hours, and you can follow the status from that same page in the Amazon Cognito console.

Figure 3: Check import job status

Figure 3: Check import job status

Cognito runs through the import job and imports users with a RESET_REQUIRED state. When users attempt to sign in, Cognito will return PasswordResetRequiredException from the sign-in API, and the app should direct the user into the ForgotPassword flow.

Figure 4: View imported user

Figure 4: View imported user

The bulk import approach can also be used continuously to incrementally import users. You can set up an Extract-Transform-Load (ETL) batch job process to extract incremental changes to your existing user directories, such as the new sign-ups on the existing systems before you switch over to a Cognito user pool. Your batch job will transform the changes into a .csv file to map user attribute schemas, and load the .csv file as a Cognito import job through the CreateUserImportJob CLI or SDK operation. Then start the import job through the StartUserImportJob CLI or SDK operation. For more information, see Importing users into user pools in the Amazon Cognito Developer Guide.

Just-in-time user migration

The just-in-time (JIT) user migration method involves first attempting to sign in the user through the Amazon Cognito user pool. Then, if the user doesn’t exist in the Cognito user pool, Cognito calls your Migrate User Lambda trigger and sends the username and password to the Lambda trigger to sign the user in through the existing user store. If successful, the Migrate User Lambda trigger will also fetch user attributes and return them to Cognito. Then Cognito silently creates the user in the user pool with user attributes, as well as salts and password verifiers from the user-provided password. With the Migrate User Lambda trigger, your client app can start to use the Cognito user pool to sign in users who have already been migrated, and continue migrating users who are signing in for the first time towards the user pool. This just-in-time migration approach helps to create a seamless authentication experience for your users.

Cognito, by default, uses the USER_SRP_AUTH authentication flow with the Secure Remote Password (SRP) protocol. This flow doesn’t involve sending the password across the network, but rather allows the client to exchange a cryptographic proof with the Cognito service to prove the client’s knowledge of the password. For JIT user migration, Cognito needs to verify the username and password against the existing user store. Therefore, you need to enable a different Cognito authentication flow. You can choose to use either the USER_PASSWORD_AUTH flow for client-side authentication or the ADMIN_USER_PASSWORD_AUTH flow for server-side authentication. This will allow the password to be sent to Cognito over an encrypted TLS connection, and allow Cognito to pass the information to the Lambda function to perform user authentication against the original user store.

This JIT approach might not be compatible with existing identity providers that have multi-factor authentication (MFA) enabled, because the Lambda function cannot support multiple rounds of challenges. If the existing identity provider requires MFA, you might consider the alternative JIT migration approach discussed later in this blog post.

Figure 5 illustrates the steps for the JIT sign-in flow. The mobile or web app first tries to sign in the user in the user pool. If the user isn’t already in the user pool, Cognito handles user authentication and invokes the Migrate User Lambda trigger to migrate the user. This flow keeps the logic in the app simple and allows the app to use the Amazon Cognito SDK to sign in users in the standard way. The migration logic takes place in the Lambda function in the backend.

Figure 5: JIT migration user authentication flow

Figure 5: JIT migration user authentication flow

The flow in Figure 5 starts in the mobile or web app, which attempts to sign in the user by using the AWS SDK. If the user doesn’t exist in the user pool, the migration attempt starts. Cognito calls the Migrate User Lambda trigger with triggerSource set to UserMigration_Authentication, and passes the user’s username and password in the request in order to attempt to migrate the user.

This approach also works in the forgot password flow shown in Figure 6, where the user has forgotten their password and hasn’t been migrated yet. In this case, once the user makes a “Forgot Password” request, your mobile or web app will send a forgot password request to Cognito. Cognito invokes your Migrate User Lambda trigger with triggerSource set to UserMigration_ForgotPassword, and passes the username in the request in order to attempt user lookup, migrate the user profile, and facilitate the password reset process.

Figure 6: JIT migration forgot password flow

Figure 6: JIT migration forgot password flow

Just-in-time user migration sample code

In this section, we show sample source codes for a Migrate User Lambda trigger overall structure. We will fill in the commented sections with additional code, shown later in the section. When you set up your own Lambda function, configure a Lambda execution role to grant permissions for CloudWatch logs.

const handler = async (event) => {
    if (event.triggerSource == "UserMigration_Authentication") {
        //***********************************************************************
        // Attempt to sign in the user or verify the password with existing identity store
        // (shown in the Section A – Migrate User of this post)
        //***********************************************************************
    }
    else if (event.triggerSource == "UserMigration_ForgotPassword") {
       //***********************************************************************
       // Attempt to look up the user in your existing identity store
       // (shown in the section B – Forget Password of this post)
       //***********************************************************************
    }
    return event;
};
export { handler };

In the migration flow, the Lambda trigger will sign in the user and verify the user’s password in the existing user store. That may involve a sign-in attempt against your existing user store or a check of the password against a stored hash. You need to customize this step based on your existing setup. You can also create a function to fetch user attributes that you want to migrate. If your existing user store conforms to the OIDC specification, you can parse the ID Token claims to retrieve the user’s attributes. The following example shows how to set the username and attributes for the migrated user.

// Section A – Migrate User
if (event.triggerSource == "UserMigration_Authentication") {
// Attempt to sign in the user or verify the password with the existing user store.
// Add an authenticateUser() functionbased on your existing user store setup. 
    const user = await authenticateUser(event.userName, event.request.password);
    if (user) {
        // Migrating user attributes from the source user store. You can migrate additional attributes as needed.
        event.response.userAttributes = {
            // Setting username and email address
            username: event.userName,
            email: user.emailAddress,
            email_verified: "true",
        };
        // Setting user status to CONFIRMED to autoconfirm users so they can sign in to the user pool
        event.response.finalUserStatus = "CONFIRMED";
        // Setting messageAction to SUPPRESS to decline to send the welcome message that Cognito usually sends to new users
        event.response.messageAction = "SUPPRESS";
        }
    }

The user is now migrated from the existing user store to the user pool, as well as the user’s attributes. Users will also be redirected to your application with the authorization code or JSON Web Tokens, depending on the OAuth 2.0 grant types you configured in the user pool.

Let’s look at the forgot password flow. Your Lambda function calls the existing user store and migrates other attributes in the user’s profile first, and then Lambda sets user attributes in the response to the Cognito user pool. Cognito initiates the ForgotPassword flow and sends a confirmation code to the user to confirm the password reset process. The user needs to have a verified email address or phone number migrated from the existing user store to receive the forgot password confirmation code. The following sample code demonstrates how to complete the ForgotPassword flow.

// Section B – Forgot Password
else if (event.triggerSource == "UserMigration_ForgotPassword") {
        // Look up the user in your existing user store service.  
		// Add a lookupUser() function based on your existing user store setup. 
        const lookupResult = await lookupUser(event.userName);
        if (lookupResult) {
            // Setting user attributes from the source user store
            event.response.userAttributes = {
                username: event.userName,
                // Required to set verified communication to receive password recovery code
                email: lookupResult.emailAddress,
                email_verified: "true",
            };
            event.response.finalUserStatus = "RESET_REQUIRED";
            event.response.messageAction = "SUPPRESS";
        }
    }

Just-in-time user migration – alternative approach

Using the Migrate User Lambda trigger, we showed the JIT migration approach where the app switches to use the Cognito user pool at the beginning of the migration period, to interface with the user for signing in and migrating them from the existing user store. An alternative JIT approach is to maintain the existing systems and user store, but to silently create each user in the Cognito user pool in a backend process as users sign in, then switch over to use Cognito after enough users have been migrated.

Figure 7: JIT migration alternative approach with backend process

Figure 7: JIT migration alternative approach with backend process

Figure 7 shows this alternative approach in depth. When an end user signs in successfully in your mobile or web app, the backend migration process is initiated. This backend process first calls the Cognito admin API operation, AdminCreateUser, to create users and map user attributes in the destination user pool. The user will be created with a temporary password and be placed in FORCE_CHANGE_PASSWORD status. If you capture the user password during the sign-in process, you can also migrate the password by setting it permanently for the newly created user in the Cognito user pool using the AdminSetUserPassword API operation. This operation will also set the user status to CONFIRMED to allow the user to sign in to Cognito using the existing password.

Following is a code example for the AdminCreateUser function using the AWS SDK for JavaScript.

var params = {
    MessageAction: "SUPPRESS",
    UserAttributes: [{
        Name: "name",
        Value: "Nikki Wolf"
    },
    {
        Name: "email",
        Value: "[email protected]"
    },
    {
        Name: "email_verified",
        Value: "True"
    }
    ],
    UserPoolId: "us-east-1_EXAMPLE",
    Username: "nikki_wolf"
};
const cognito = new CognitoIdentityProviderClient();
const createUserCommand  = new AdminCreateUserCommand(params);
await cognito.send (createUserCommand);

The following is a code example for the AdminSetUserPassword function.

var params = {
    UserPoolId: 'us-east-1_EXAMPLE' ,
    Username: 'nikki_wolf' ,
    Password: 'ExamplePassword1$' ,
    Permanent: true
};
const cognito = new CognitoIdentityProviderClient();
const setUserPasswordCommand = new AdminSetUserPasswordCommand(params);
await cognito.send(setUserPasswordCommand);

This alternative approach does not require the app to update its authentication codebase until a majority of users are migrated, but you need to propagate user attribute changes and new user signups from the existing systems to Cognito. If you are capturing and migrating passwords, you should also build a similar logic to capture password changes in existing systems and set the new password in the user pool to keep it synchronized until you perform a full switchover from the existing identity store to the Cognito user pool.

Summary and best practices

In this post, we described our two recommended approaches for migrating users into an Amazon Cognito user pool. You can decide which approach is best suited for your use case. The bulk method is simpler to implement, but it doesn’t preserve user passwords like the just-in-time migration does. The just-in-time migration is transparent to users and mitigates the potential attrition of users that can occur when users need to reset their passwords.

You could also consider a hybrid approach, where you first apply JIT migration as users are actively signing in to your app, and perform bulk import for the remaining less-active users. This hybrid approach helps provide a good experience for your active user communities, while being able to decommission existing user stores in a manageable timeline because you don’t need to wait for every user to sign in and be migrated through JIT migration.

We hope you can use these explanations and code samples to set up the most suitable approach for your migration project.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, contact AWS Support.

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Edward Sun

Edward Sun

Edward is a Security Specialist Solutions Architect focused on identity and access management. He loves helping customers throughout their cloud transformation journey with architecture design, security best practices, migration, and cost optimizations. Outside of work, Edward enjoys hiking, golfing, and cheering for his alma mater, the Georgia Bulldogs.

Scaling national identity schemes with itsme and Amazon Cognito

Post Syndicated from Guillaume Neau original https://aws.amazon.com/blogs/security/scaling-national-identity-schemes-with-itsme-and-amazon-cognito/

In this post, we demonstrate how you can use identity federation and integration between the identity provider itsme® and Amazon Cognito to quickly consume and build digital services for citizens on Amazon Web Services (AWS) using available national digital identities. We also provide code examples and integration proofs of concept to get you started quickly.

National digital identities refer to a system or framework that a government establishes to uniquely and securely identify its citizens or residents in the digital realm.

These national digital identities are built on a rigorous process of identity verification and enforce the use of high security standards when it comes to authentication mechanisms. Their adoption by both citizens and businesses helps to fight identity theft, most notably by removing the need to send printed copies of identity documents.

National certified secure digital identities are suitable for both businesses and public services and can improve the onboarding experience by reducing the need to create new credentials.

About itsme

itsme is a trusted identity provider (certified and notified for all 27 member states of EU at Level of Assurance HIGH of the eiDAS regulation) that can be used on over 800 government and company platforms to identify yourself online, log in, confirm transactions, or sign documents. It allows partners to use its verified identities for authentication and authorization on web, desktop, mobile web, and mobile applications.

As of this writing, itsme is accessible for all residents in Belgium, The Netherlands, and Luxembourg. However, since there are no limitations on the geographic usage of the identity and electronic signature APIs, itsme has the potential to expand to additional countries in the future. (Source: itsme, 2023)

Architecture overview

To demonstrate the integration, you’re going to build a minimalistic application made of the following components as shown in Figure 1 that follows:

Figure 1: Architectural diagram

Figure 1: Architectural diagram

After deployment, you can log in and interact with the application:

  1. Visit the frontend deployed locally, and you’re presented the option to authenticate with itsme by using a blue colored button. Choose the button to proceed.
  2. After being redirected to itsme, you’re asked to either create a new account or to use an existing one for authentication. After you’re successfully authenticated with itsme, the associated Amazon Cognito user pool is populated with the requested data in the scope of the federation. Specifically in this example, the national registration number is made available.
  3. When authenticated, you’re redirected to the frontend, and you can read and write messages to and from the database behind an Amazon API Gateway.
  4. The Amazon API Gateway uses Amazon Cognito to check the validity of your authentication token.
  5. The Lambda function reads and writes messages to and from DynamoDB.

Prerequisites to deploy the identity federation with itsme

While setting up the Amazon Cognito user pool, you’re asked for the following information:

  • An itsme client ID – itsmeClientId
  • An itsme client secret – itsmeClientSecret
  • An itsme service code – itsmeServiceCode
  • An itsme issuer URL – itsmeIssuerUrl

To retrieve this information, you must be an itsme partner and to have your sandbox requested and available. The sandbox should be made available three business days after you submit the dedicated request form to itsme.

After the sandbox is provisioned, you must contact the itsme support desk and ask to switch the sandbox authentication to the client secret – itsmeClientSecret flow. Include the link to this post and specify that it’s for establishing a federation with Amazon Cognito.

Implement the proof of concept

To implement this proof of concept, you need to follow these steps:

  1. Create an Amazon Cognito user pool.
  2. Configure the Amazon Cognito user pool.
  3. Deploy a sample API.
  4. Configure your application.

To create and configure an Amazon Cognito user pool

  1. Sign in to the AWS Management Console and enter cognito in the search bar at the top. Select Cognito from the Services results.
    Figure 2: Select Cognito service

    Figure 2: Select Cognito service

  2. In the Amazon Cognito console, select User pools, and then choose Create user pool.
    Figure 3: Cognito user pool creation

    Figure 3: Cognito user pool creation

  3. To configure the sign-in experience section, select Federated identity providers as the authentication providers.
  4. In the Cognito user pool sign-in options area, select User name, Email, and Phone number.
  5. In the Federated sign-in options area, select OpenID Connect (OIDC).
    Figure 4: Sign-in configuration

    Figure 4: Sign-in configuration

  6. Choose Next to continue to security requirements.

Note: In this post, account management and authentication are restricted to itsme. Because of this, the password length, multi-factor authentication, and recovery procedures are delegated to itsme. If you don’t restrict your Cognito user pool to itsme only, configure it according to your security requirements.

To configure the security requirements

  1. For Password policy, select Cognito defaults.
  2. Select Require MFA – Recommended in the Multi-factor authentication area, and select Authenticator apps

    Note: Although the activation of multi-factor authentication is recommended, it’s important to understand that users of this pool will be created and authenticated through the federation with itsme. In the next procedure, you disable the Self service sign-up feature to prevent users from creating accounts. As itsme is compliant with the level of assurance substantial of the eIDAS regulation, itsme users must log in using a second factor of authentication.

  3. Clear Enable self-service account recovery in the User account recovery area.
Figure 5: Security requirements configuration

Figure 5: Security requirements configuration

To configure the sign-up experience

  1. Clear Enable self-registration.
  2. Clear Allow Cognito to automatically send messages to verify and confirm.
    Figure 6: Sign-up configuration

    Figure 6: Sign-up configuration

  3. Skip the configuration of required attributes and configure custom attributes. Expand the drop-down menu and add the following custom attributes:
    1. Name: eid.
    2. Type: String.
    3. Leave Min and Max length blank.
    4. Mutable: Select.

    This custom attribute is used to map and store the national registration number.

  4. Choose Next to configure message delivery.

Note: In this post, account management and authentication are going to be restricted to itsme. As a result, Amazon Cognito doesn’t send email or SMS, and the prescribed configuration is minimal. If you don’t limit your user pool to itsme, configure message delivery parameters according to your corporate policy.

To configure message delivery

  1. For Email, select Send email with Cognito and leave the other fields with their default configuration.
  2. To configure the SMS, select Create a new IAM Role if you don’t already have one provisioned.
  3. Choose Next to configure the federated identity provider.
    Figure 7: Message delivery configuration

    Figure 7: Message delivery configuration

  4. Choose Next to configure identity provider.

To configure the federated identity provider

  1. For Provider name, enter itsme.
  2. For Client ID, enter the client ID provided by itsme.
  3. For Client secret, enter the client secret provided by itsme.
  4. For Authorized scopes, start with the mandatory service:itsmeServiceCode.
  5. With a space between each scope, enter openid profile eid email address.
  6. For Retrieve OIDC endpoints, enter the issuer URL provided by itsme.
    Figure 8: OIDC federation configuration

    Figure 8: OIDC federation configuration

    The configuration of the mapping of the attributes can be done according to the documentation provided by itsme.

    An example of mapping is provided in Figure 9 that follows. Some differences exist to be able to retrieve and map the eID and the unique username of itsme (sub).

    More specifically, to retrieve the National Registration Number, the eid field needs to be set to http://itsme.services/v2/claim/BENationalNumber.

    Figure 9: Attributes mapping

    Figure 9: Attributes mapping

  7. Choose Next to configure an app client.

To configure an app client

  1. Configure both your user pool name and domain by opening the Amazon Cognito console.
    Figure 10: User pool and domain name

    Figure 10: User pool and domain name

  2. In the Initial app client area, select Public client.
    1. Enter your application client name.
    2. Select Don’t generate a client secret.
    3. Enter the application callback URL that’s used by itsme at the end of the authenticating flow. This URL is the one your end user is going to land on after authenticating.
    Figure 11: Configuring app client

    Figure 11: Configuring app client

To finish the creation by reviewing and creating the user pool

When the user pool is created, send your Amazon Cognito domain name to itsme support for them to activate your authentication endpoints. That URL has the following composition:

https://<Your user pool domain>.auth.<your region>.amazoncognito.com/oauth2/idpresponse

When the user pool is created, you can retrieve your userPoolWebClientId, which is required to create a consuming application.

To retrieve your userPoolWebClientId

  1. From the Amazon Cognito Console, select User pools on the left menu.
  2. Select the user pool that you created.
    Figure 12: User pool app integration

    Figure 12: User pool app integration

In the App integration area, your userPoolWebClientId is displayed at the bottom of the window.

Figure 13: Client ID

Figure 13: Client ID

To create a consuming application

When the setup of the user pool is done, you can integrate the authenticating flow in your application. The integration can be done using the AWS Amplify SDK and by calling the relevant API directly. Depending of the framework you used when building the application, you can find documentation about doing so in AWS Prescriptive Guidance Patterns.

You can use Amazon API Gateway to quickly build a secure API that uses the authentication made through Amazon Cognito and the federation to build services. We encourage you to review the Amazon API Gateway documentation to learn more. The next section provides you with examples that you can deploy to get an idea of the integration steps.

Additionally, you can use an Amazon Cognito identity pool to exchange Amazon Cognito issued tokens for AWS credentials (in other words, assuming AWS Identity and Access Management (IAM) roles) to access other AWS services. As an example, this could allow users to upload files to an Amazon Simple Storage Service (Amazon S3) bucket.

About the examples provided

The public GitHub repository that is provided contains code examples and associated documentation to help you automatically go through the setup steps detailed in this post. Specifically, the following are available:

  1. An AWS Cloudformation template that can help you provision a properly set-up user pool after you have the required information from itsme.
  2. An AWS Cloudformation template that deploys the backend for the test application.
  3. A React frontend that you can run locally to interact with the backend and to consume identities from itsme.

To deploy the provided examples

  1. Clone the repository on your local machine.
  2. Install the dependencies.
  3. If you haven’t created your user pool following the instructions in this post, you can use the CognitoItsmeStack provided as an example.
  4. Deploy the associated backend stack BackendItsmeStack.cfn.yaml.
  5. Rename the frontend/src/config.json.template file to frontend/src/config.json and replace the following:
    1. region with the AWS Region associated with your Amazon Cognito user pool.
    2. userPoolId with the assigned ID of the user pool that you created.
    3. userPoolWebClientId with the client ID that you retrieved.
    4. domain with your Amazon Cognito domain in the form of <your user pool name>.auth.<your region>.amazoncognito.com
    Figure 14: Frontend configuration file

    Figure 14: Frontend configuration file

  6. After modifications are done, start the application on your local machine with the provided command.

Following authentication, the results in the associated collected data are displayed, as shown in Figure 15 that follows.

Figure 15: User information

Figure 15: User information

In the My Data section, you can access a form to input a value (shown in Figure 16). Each time you go back to this page, the previous value entered is shown in the input box. This input is associated with your NRN (custom:eid), and only you can access it.

Figure 16: Database interaction

Figure 16: Database interaction

Conclusion

You can now consume digital identities through identity federation between Amazon Cognito and itsme. We hope that it helps you build secure digital services to improve the life of Benelux users.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, contact AWS Support.

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Guillaume Neau

Guillaume is a Solutions Architect from France with expertise in information security that focuses on building solutions that improve customers’ lives.bio text

Julien Martin

Julien Martin

Julien is a Solutions Architect at Amazon Web Services (AWS) supporting public institutions (such as local governments and cities) in Benelux. He has over 20 years of industry experience in helping customers design, build, implement, and operate enterprise applications.

Use SAML with Amazon Cognito to support a multi-tenant application with a single user pool

Post Syndicated from Neela Kulkarni original https://aws.amazon.com/blogs/security/use-saml-with-amazon-cognito-to-support-a-multi-tenant-application-with-a-single-user-pool/

Amazon Cognito is a customer identity and access management solution that scales to millions of users. With Cognito, you have four ways to secure multi-tenant applications: user pools, application clients, groups, or custom attributes. In an earlier blog post titled Role-based access control using Amazon Cognito and an external identity provider, you learned how to configure Cognito authentication and authorization with a single tenant. In this post, you will learn to configure Cognito with a single user pool for multiple tenants to securely access a business-to-business application by using SAML custom attributes. With custom-attribute–based multi-tenancy, you can store tenant identification data like tenantName as a custom attribute in a user’s profile and pass it to your application. You can then handle multi-tenancy logic in your application and backend services. With this approach, you can use a unified sign-up and sign-in experience for your users. To identify the user’s tenant, your application can use the tenantName custom attribute.

One Cognito user pool for multiple customers

Customers like the simplicity of using a single Cognito user pool for their multi-customer application. With this approach, your customers will use the same URL to access the application. You will set up each new customer by configuring SAML 2.0 integration with the customer’s external identity provider (IdP). Your customers can control access to your application by using an external identity store, such as Google Workspace, Okta, or Active Directory Federation Service (AD FS), in which they can create, manage, and revoke access for their users.

After SAML integration is configured, Cognito returns a JSON web token (JWT) to the frontend during the user authentication process. This JWT contains attributes your application can use for authorization and access control. The token contains claims about the identity of the authenticated user, such as name and email. You can use this identity information inside your application. You can also configure Cognito to add custom attributes to the JWT, such as tenantName.

In this post, we demonstrate the approach of keeping a mapping between a user’s email domain and tenant name in an Amazon DynamoDB table. The DynamoDB table will have an emailDomain field as a key and a corresponding tenantName field.

Cognito architecture

To illustrate how this works, we’ll start with a demo application that was introduced in the earlier blog post. The demo application is implemented by using Amazon Cognito, AWS Amplify, Amazon API Gateway, AWS Lambda, Amazon DynamoDB, Amazon Simple Storage Service (Amazon S3), and Amazon CloudFront to achieve a serverless architecture. This architecture is shown in Figure 1.

Figure 1: Demo application architecture

Figure 1: Demo application architecture

The workflow that happens when you access the web application for the first time using your browser is as follows (the numbered steps correspond to the numbered labels in the diagram):

  1. The client-side/frontend of the application prompts you to enter the email that you want to use to sign in to the application.
  2. The application invokes the Tenant Match API action through API Gateway, which, in turn, calls the Lambda function that takes the email address as an input and queries it against the DynamoDB table with the email domain. Figure 2 shows the data stored in DynamoDB, which includes the tenant name and IdP ID. You can add additional flexibility to this solution by adding web client IDs or custom redirect URLs. For the purpose of this example, we are using the same redirect URL for all tenants (the client application).
    Figure 2: DynamoDB tenant table

    Figure 2: DynamoDB tenant table

  3. If a matching record is found, the Lambda function returns the record to the AWS Amplify frontend application.
  4. The client application uses the IdP ID from the response and passes it to Cognito for federated login. Cognito then reroutes the login request to the corresponding IdP. The AWS Amplify frontend application then redirects the browser to the IdP.
  5. At the IdP sign-in page, you sign in with a valid user account (for example, [email protected] or [email protected]). After you sign in successfully, a SAML response is sent back from the IdP to Cognito.

    You can review the SAML content by using the instructions in How to view a SAML response in your browser for troubleshooting, as shown in Figure 3.

    Figure 3: SAML content

    Figure 3: SAML content

  6. Cognito handles the SAML response and maps the SAML attributes to a just-in-time user profile. The SAML groups attributes is mapped to a custom user pool attribute named custom:groups.
  7. To identify the tenant, additional attributes are populated in the JWT. After successful authentication, a PreTokenGeneration Lambda function is invoked, which reads the mapped custom:groups attribute value from SAML, parses it, and converts it to an array. After that, the function parses the email address and captures the domain name. It then queries the DynamoDB table for the tenantName name by using the email domain name. Finally, the function sets the custom:domainName and custom:tenantName attributes in the JWT, as shown following.
    "email": "[email protected]" ( Standard existing profile attribute )
    New attributes:
    "cognito:groups": [.                           
    "pet-app-users",
    "pet-app-admin"
    ],
    "custom:tenantName": "AnyCompany"
    "custom:domainName": "anycompany.com"

    This attribute conversion is optional and demonstrates how you can use a PreTokenGeneration Lambda invocation to customize your JWT token claims, mapping the IdP groups to the attributes your application recognizes. You can also use this invocation to make additional authorization decisions. For example, if user is a member of multiple groups, you may choose to map only one of them.

  8. Amazon Cognito returns the JWT tokens to the AWS Amplify frontend application. The Amplify client library stores the tokens and handles refreshes. This token is used to make calls to protected APIs in Amazon API Gateway.
  9. API Gateway uses a Cognito user pools authorizer to validate the JWT’s signature and expiration. If this is successful, API Gateway passes the JWT to the application’s Lambda function (also referred to as the backend).
  10. The backend application code reads the cognito:groups claim from the JWT and decides if the action is allowed. If the user is a member of the right group, then the action is allowed; otherwise the action is denied.

Implement the solution

You can implement this example application by using an AWS CloudFormation template to provision your cloud application and AWS resources.

To deploy the demo application described in this post, you need the following prerequisites:

  1. An AWS account.
  2. Familiarity with navigating the AWS Management Console or AWS CLI.
  3. Familiarity with deploying CloudFormation templates.

To deploy the template

  • Choose the following Launch Stack button to launch a CloudFormation stack in your account.

    Select this image to open a link that starts building the CloudFormation stack

    Note: The stack will launch in the N. Virginia (us-east-1) Region. To deploy this solution into other AWS Regions, download the solution’s CloudFormation template from GitHub, modify it, and deploy it to the selected Region.

The stack creates a Cognito user pool called ExternalIdPDemoPoolXXXX in the AWS Region that you have specified. The CloudFormation Outputs field contains a list of values that you will need for further configuration.

IdP configuration

The next step is to configure your IdP. Each IdP has its own procedure for configuration, but there are some common steps you need to follow.

To configure your IdP

  1. Provide the IdP with the values for the following two properties:
    • Single sign on URL / Assertion Consumer Service URL / ACS URL (for this example, https://<CognitoDomainURL>/saml2/idpresponse)
    • Audience URI / SP Entity ID / Entity ID: (For this example, urn:amazon:cognito:sp:<yourUserPoolID>)
  2. Configure the field mapping for the SAML response in the IdP. Map the first name, last name, email, and groups (as a multi-value attribute) into SAML response attributes with the names firstName, lastName, email, and groups, respectively.
    • Recommended: Filter the mapped groups to only those that are relevant to the application (for example, by a prefix filter). There is a 2,048-character limit on the custom attribute, so filtering helps avoid exceeding the character limit, and also helps avoid passing irrelevant information to the application.
  3. In each IdP, create two demo groups called pet-app-users and pet-app-admins, and create two demo users, for example, [email protected] and [email protected], and then assign one to each group, respectively.

To illustrate, we set up three different IdPs to represent three different tenants. Use the following links for instructions on how to configure each IdP:

You will need the metadata URL or file from each IdP, because you will use this to configure your user pool integration. For more information, see Integrating third-party SAML identity providers with Amazon Cognito user pools.

Cognito configuration

After your IdPs are configured and your CloudFormation stack is deployed, you can configure Cognito.

To configure Cognito

  1. Use your browser to navigate to the Cognito console, and for User pool name, select the Cognito user pool.
    Figure 4: Select the Cognito user pool

    Figure 4: Select the Cognito user pool

  2. On the Sign-in experience screen, on the Federated identity provider sign-in tab, choose Add identity provider.
  3. Choose SAML for the sign-in option, and then enter the values for your IdP. You can either upload the metadata XML file or provide the metadata endpoint URL. Add mapping for the attributes as shown in Figure 5.
    Figure 5: Attribute mappings for the IdP

    Figure 5: Attribute mappings for the IdP

    Upon completion you will see the new IdP displayed as shown in Figure 6.

    Figure 6: List of federated IdPs

    Figure 6: List of federated IdPs

  4. On the App integration tab, select the app client that was created by the CloudFormation template.
    Figure 7: Select the app client

    Figure 7: Select the app client

  5. Under Hosted UI, choose Edit. Under Identity providers, select the Identity Providers that you want to set up for federated login, and save the change.
    Figure 8: Select identity providers

    Figure 8: Select identity providers

API gateway

The example application uses a serverless backend. There are two API operations defined in this example, as shown in Figure 9. One operation gets tenant details and the other is the /pets API operation, which fetches information on pets based on user identity. The TenantMatch API operation will be run when you sign in with your email address. The operation passes your email address to the backend Lambda function.

Figure 9: Example APIs

Figure 9: Example APIs

Lambda functions

You will see three Lambda functions deployed in the example application, as shown in Figure 10.

Figure 10: Lambda functions

Figure 10: Lambda functions

The first one is GetTenantInfo, which is used for the TenantMatch API operation. It reads the data from the TenantTable based on the email domain and passes the record back to the application. The second function is PreTokenGeneration, which reads the mapped custom:groups attribute value, parses it, converts it to an array, and then stores it in the cognito:groups claim. The second Lambda function is invoked by the Cognito user pool after sign-in is successful. In order to customize the mapping, you can edit the Lambda function’s code in the index.js file and redeploy. The third Lambda function is added to support the Pets API operation.

DynamoDB tables

You will see three DynamoDB tables deployed in the example application, as shown in Figure 11.

Figure 11: DynamoDB tables

Figure 11: DynamoDB tables

The TenantTable table holds the tenant details where you must add the mapping between the customer domain and the IdP ID setup in Cognito. This approach can be expanded to add more flexibility in case you want to add custom redirect URLs or Cognito app IDs for each tenant. You must create entries to correspond to the IdPs you have configured, as shown in Figure 12.

Figure 12: Tenant IdP mappings table

Figure 12: Tenant IdP mappings table

In addition to TenantTable, there is the ExternalIdPDemo-ItemsTable table, which holds the data related to the Pets application, based on user identity. There is also ExternalIdPDemo-UsersTable, which holds user details like the username, last forced sign-out time, and TTL required for the application to manage the user session.

You can now sign in to the example application through each IdP by navigating to the application URL found in the CloudFormation Outputs section, as shown in Figure 13.

Figure 13: Cognito sign-in screen

Figure 13: Cognito sign-in screen

You will be redirected to the IdP, as shown in Figure 14.

Figure 14: Google Workspace sign-in screen

Figure 14: Google Workspace sign-in screen

The AWS Amplify frontend application parses the JWT to identify the tenant name and provide authorization based on group membership, as shown in Figure 15.

Figure 15: Application home screen upon successful sign-in

Figure 15: Application home screen upon successful sign-in

If a different user logs in with a different role, the AWS Amplify frontend application provides authorization based on specific content of the JWT.

Conclusion

You can integrate your application with your customer’s IdP of choice for authentication and authorization and map information from the IdP to the application. By using Amazon Cognito, you can normalize the structure of the JWT token that is used for this process, so that you can add multiple IdPs, each for a different tenant, through a single Cognito user pool. You can do all this without changing application code. The native integration of Amazon API Gateway with the Cognito user pools authorizer streamlines your validation of the JWT integrity, and after the JWT has been validated, you can use it to make authorization decisions in your application’s backend. By following the example in this post, you can focus on what differentiates your application, and let AWS do the undifferentiated heavy lifting of identity management for your customer-facing applications.

For the code examples described in this post, see the amazon-cognito-example-for-multi-tenant code repository on GitHub. To learn more about using Cognito with external IdPs, see the Amazon Cognito documentation. You can also learn to build software as a service (SaaS) application architectures on AWS. If you have any questions about Cognito or any other AWS services, you may post them to AWS re:Post.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, start a new thread on the AWS Security, Identity, & Compliance re:Post or contact AWS Support.

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Ray Zaman

Ray Zaman

A Principal Solutions Architect with AWS, Ray has over 30 years of experience helping customers in finance, healthcare, insurance, manufacturing, media, petrochemical, pharmaceutical, public utility, retail, semiconductor, telecommunications, and waste management industries build technology solutions.

Neela Kulkarni

Neela Kulkarni

Neela is a Solutions Architect with Amazon Web Services. She primarily serves independent software vendors in the Northeast US, providing architectural guidance and best practice recommendations for new and existing workloads. Outside of work, she enjoys traveling, swimming, and spending time with her family.

Yuri Duchovny

Yuri Duchovny

Yuri is a New York–based Solutions Architect specializing in cloud security, identity, and compliance. He supports cloud transformations at large enterprises, helping them make optimal technology and organizational decisions. Prior to his AWS role, Yuri’s areas of focus included application and networking security, DoS, and fraud protection. Outside of work, he enjoys skiing, sailing, and traveling the world.

Abdul Qadir

Abdul Qadir

Abdul is an AWS Solutions Architect based in New Jersey. He works with independent software vendors in the Northeast US and helps customers build well-architected solutions on the AWS Cloud platform.

Should I use the hosted UI or create a custom UI in Amazon Cognito?

Post Syndicated from Joshua Du Lac original https://aws.amazon.com/blogs/security/use-the-hosted-ui-or-create-a-custom-ui-in-amazon-cognito/

Amazon Cognito is an authentication, authorization, and user management service for your web and mobile applications. Your users can sign in directly through many different authentication methods, such as native accounts within Amazon Cognito or through a social login, such as Facebook, Amazon, or Google. You can also configure federation through a third-party OpenID Connect (OIDC) or SAML 2.0 identity provider (IdP).

Cognito user pools are user directories that provide sign-up and sign-in functions for your application users, including federated authentication capabilities. A Cognito user pool has two primary UI options:

  • Hosted UI — AWS hosts, preconfigures, maintains, and scales the UI, with a set of options that you can customize or configure for sign-up and sign-in for app users.
  • Custom UI — You configure a Cognito user pool with a completely custom UI by using the SDK. You are accountable for hosting, configuring, maintaining, and scaling your custom UI as a part of your responsibility in the AWS Shared Responsibility Model.

In this blog post, we will review the benefits of using the hosted UI or creating a custom UI with the SDK, as well as things to consider in determining which to choose for your application (app).

Hosted UI

Using the Cognito Hosted UI provides many benefits and features that can help you to quickly configure a UI for your app users. The hosted UI provides an OAuth 2.0 aligned authorization server, and it has a default implementation of end-user flows for sign-up and sign-in. Your application can redirect to the hosted UI, which will handle the user flows through the Authorization Code Grant flow. The hosted UI also supports sign-in through social providers and federation from OIDC-compliant and SAML 2.0 providers. Basic customizations are supported—for example, you can add multi-factor authentication (MFA) by adjusting the configuration of your Cognito user pool. The hosted UI supports brand-specific logos along with other UI design customization elements.

With the hosted UI, you have a set of preconfigured features that are designed to help you meet your compliance and security requirements as well as your users’ needs. The hosted UI allows for custom OAuth scopes and OAuth 2.0 flows. If you want single sign-on (SSO), you can use the hosted UI to support a single login across many app clients, which uses the browser session cookies for the same domain. For logging, actions are logged in AWS CloudTrail, and you can use the logs for audit and reactionary automation. The hosted UI also supports the full suite of advanced security features for Amazon Cognito. For additional protection, the hosted UI has support for AWS WAF integration and for AWS WAF CAPTCHA, which you can use to help protect your Cognito user pools from web-based attacks and unwanted bots.

Figure 1: Example default hosted UI with several login providers enabled

Figure 1: Example default hosted UI with several login providers enabled

For federation, the hosted UI supports federation from third-party IdPs that support OIDC and SAML 2.0, as well as social IdPs, as shown in Figure 1. Linking your federation source or sources occurs at the level of the Cognito user pool; this creates a simple button option for the app user to select the federation source, and redirection is automatic. If you are managing native SAML IdPs, you can also configure mapping by using the domain in the user’s email address. In this case, a single text field is visible to your app users to enter an email address, as shown in Figure 2, and the lookup and redirect to the appropriate SAML IdP is automatic, as described in Choosing SAML identity provider names.

Figure 2: Hosted UI that links to corporate IdP through an email domain

Figure 2: Hosted UI that links to corporate IdP through an email domain

The Cognito hosted UI integrates directly with several other AWS services. When using the hosted UI, Amazon API Gateway and Application Load Balancer offer built-in enforcement points to evaluate access based on Cognito tokens and scopes. Additionally, AWS Amplify uses Amazon Cognito for user sign-up and sign-in under the hood.

You might choose to use the hosted UI for many reasons. AWS fully manages the hosting, maintenance, and scaling of the hosted UI, which can contribute to the speed of go-to-market for customers. If your app requires OAuth 2.0 custom scopes, federation, social login, or native users with simple but customized branding and potentially numerous Cognito user pools, you might benefit from using the hosted UI.

For more information about how to configure and use the hosted UI, see Using the Amazon Cognito hosted UI for sign-up and sign-in.

Create a custom UI

Creating a custom UI using the SDK for Cognito provides a host of benefits and features that can help you completely customize a UI for your app users. With a custom UI, you have complete control over the look and feel of the UI that your app users will land on, you can design your app to support multiple languages, and you can build and design custom authentication flows.

There are numerous features that are supported when you build a custom UI. As with the hosted UI, a custom UI supports logging of actions in CloudTrail, and you can use the logs for audit and reactionary automation. You can also create a custom authentication flow for your users to include additional methods of authentication beyond a traditional login flow with username and password.

Note: Device tracking and adaptive authentication are not compatible with custom authentication flows.

In a custom UI, you can adjust the session expiration configuration to less than one hour, and there is support for AWS WAF. A custom UI also supports several advanced security features.

Figure 3: Example of a custom user interface

Figure 3: Example of a custom user interface

For federation, a custom UI supports mapping to a specific IdP through the app user’s email domain for both SAML and OIDC IdPs. As with the hosted UI, you would design a single text field that is visible to your app users to enter an email address, and you can achieve the lookup and redirect to the appropriate SAML or OIDC IdP by following the steps at the bottom of the documentation page Choosing SAML identity provider names.

Figure 4: Custom UI example

Figure 4: Custom UI example

When you build a custom UI, there is support for custom endpoints and proxies so that you have a wider range of options for management and consistency across app development as it relates to authentication. Having a custom UI, support is present for custom authentication flows, which gives you the ability to make customized challenge and response cycles to help you meet different requirements by using AWS Lambda triggers. For example, you could use it to implement OAuth 2.0 device grant flows. Lastly, a custom UI supports device fingerprinting where you might need it within the app or for authentication purposes.

You might choose to build a custom UI with the SDK where full customization is a requirement or where you want to incorporate customized authentication flows. A custom UI is a great choice if you aren’t required to use OAuth 2.0 flows and you are willing to take the time to develop a unique UI for your app users.

Decision criteria matrix

Although numerous features are supported by both the hosted UI and a custom UI, there are some unique differences that can help you determine which UI is best for your app needs. If your app requires OAuth 2.0 flows, custom OAuth scopes, the ability to login once across many Cognito app clients (SSO), or full use of the advanced security features, then we recommend that you use the hosted UI. However, if you want full customization of the UI, custom authentication flows, device fingerprinting, or reduced token expiration, then a custom UI is the better choice. These features target your app authentication requirements and customer experience and should take precedence over other considerations. You can use the following table to help select the best UI for your requirements.

Figure 5: Decision criteria matrix

Figure 5: Decision criteria matrix

Conclusion

In this post, you learned about using the hosted UI and creating a custom UI in Amazon Cognito and the many supported features and benefits of each. Each UI option targets a specific need, and you should consider which to choose based on your list of requirements for authentication and the user sign-up and sign-in experience. You can use the information outlined in this post as a reference as you add Amazon Cognito to your mobile and web apps for authentication.

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Joshua Du Lac

Josh is a Senior Manager of Security Solutions Architects at AWS. He has advised hundreds of enterprise, global, and financial services customers to accelerate their journey to the cloud while improving their security along the way. Outside of work, Josh enjoys searching for the best tacos in Texas and practicing his handstands.

Jeremy Wave

Jeremy Ware

Jeremy is a Security Specialist Solutions Architect focused on Identity and Access Management. Jeremy and his team enable AWS customers to implement sophisticated, scalable, and secure IAM architecture and Authentication workflows to solve business challenges. With a background in Security Engineering, Jeremy has spent many years working to raise the Security Maturity gap at numerous global enterprises. Outside of work, Jeremy loves to explore the mountainous outdoors, and participate in sports such as snowboarding, wakeboarding, and dirt bike riding.

dApp authentication with Amazon Cognito and Web3 proxy with Amazon API Gateway

Post Syndicated from Nicolas Menciere original https://aws.amazon.com/blogs/architecture/dapp-authentication-with-amazon-cognito-and-web3-proxy-with-amazon-api-gateway/

If your decentralized application (dApp) must interact directly with AWS services like Amazon S3 or Amazon API Gateway, you must authorize your users by granting them temporary AWS credentials. This solution uses Amazon Cognito in combination with your users’ digital wallet to obtain valid Amazon Cognito identities and temporary AWS credentials for your users. It also demonstrates how to use Amazon API Gateway to secure and proxy API calls to third-party Web3 APIs.

In this blog, you will build a fully serverless decentralized application (dApp) called “NFT Gallery”. This dApp permits users to look up their own non-fungible token (NFTs) or any other NFT collections on the Ethereum blockchain using one of the following two Web3 providers HTTP APIs: Alchemy or Moralis. These APIs help integrate Web3 components in any web application without Blockchain technical knowledge or access.

Solution overview

The user interface (UI) of your dApp is a single-page application (SPA) written in JavaScript using ReactJS, NextJS, and Tailwind CSS.

The dApp interacts with Amazon Cognito for authentication and authorization, and with Amazon API Gateway to proxy data from the backend Web3 providers’ APIs.

Architecture diagram

Architecture diagram showing authentication and API request proxy solution for Web3

Figure 1. Architecture diagram showing authentication and API request proxy solution for Web3

Prerequisites

Using the AWS SAM framework

You’ll use AWS SAM as your framework to define, build, and deploy your backend resources. AWS SAM is built on top of AWS CloudFormation and enables developers to define serverless components using a simpler syntax.

Walkthrough

Clone this GitHub repository.

Build and deploy the backend

The source code has two top level folders:

  • backend: contains the AWS SAM Template template.yaml. Examine the template.yaml file for more information about the resources deployed in this project.
  • dapp: contains the code for the dApp

1. Go to the backend folder and copy the prod.parameters.example file to a new file called prod.parameters. Edit it to add your Alchemy and Moralis API keys.

2. Run the following command to process the SAM template (review the sam build Developer Guide).

sam build

3. You can now deploy the SAM Template by running the following command (review the sam deploy Developer Guide).

sam deploy --parameter-overrides $(cat prod.parameters) --capabilities CAPABILITY_NAMED_IAM --guided --confirm-changeset

4. SAM will ask you some questions and will generate a samconfig.toml containing your answers.

You can edit this file afterwards as desired. Future deployments will use the .toml file and can be run using sam deploy. Don’t commit the samconfig.toml file to your code repository as it contains private information.

Your CloudFormation stack should be deployed after a few minutes. The Outputs should show the resources that you must reference in your web application located in the dapp folder.

Run the dApp

You can now run your dApp locally.

1. Go to the dapp folder and copy the .env.example file to a new file named .env. Edit this file to add the backend resources values needed by the dApp. Follow the instructions in the .env.example file.

2. Run the following command to install the JavaScript dependencies:

yarn

3. Start the development web server locally by running:

yarn dev

Your dApp should now be accessible at http://localhost:3000.

Deploy the dApp

The SAM template creates an Amazon S3 bucket and an Amazon CloudFront distribution, ready to serve your Single Page Application (SPA) on the internet.

You can access your dApp from the internet with the URL of the CloudFront distribution. It is visible in your CloudFormation stack Output tab in the AWS Management Console, or as output of the sam deploy command.

For now, your S3 bucket is empty. Build the dApp for production and upload the code to the S3 bucket by running these commands:

cd dapp
yarn build
cd out
aws s3 sync . s3://${BUCKET_NAME}

Replace ${BUCKET_NAME} by the name of your S3 bucket.

Automate deployment using SAM Pipelines

SAM Pipelines automatically generates deployment pipelines for serverless applications. If changes are committed to your Git repository, it automates the deployment of your CloudFormation stack and dApp code.

With SAM Pipeline, you can choose a Git provider like AWS CodeCommit, and a build environment like AWS CodePipeline to automatically provision and manage your deployment pipeline. It also supports GitHub Actions.

Read more about the sam pipeline bootstrap command to get started.

Host your dApp using Interplanetary File System (IPFS)

IPFS is a good solution to host dApps in a decentralized way. IPFS Gateway can serve as Origin to your CloudFront distribution and serve IPFS content over HTTP.

dApps are often hosted on IPFS to increase trust and transparency. With IPFS, your web application source code and assets are not tied to a DNS name and a specific HTTP host. They will live independently on the IPFS network.

Read more about hosting a single-page website on IPFS, and how to run your own IPFS cluster on AWS.

Secure authentication and authorization

In this section, we’ll demonstrate how to:

  • Authenticate users via their digital wallet using Amazon Cognito user pool
  • Protect your API Gateway from the public internet by authorizing access to both authenticated and unauthenticated users
  • Call Alchemy and Moralis third party APIs securely using API Gateway HTTP passthrough and AWS Lambda proxy integrations
  • Use the JavaScript Amplify Libraries to interact with Amazon Cognito and API Gateway from your web application

Authentication

Your dApp is usable by both authenticated and unauthenticated users. Unauthenticated users can look up NFT collections while authenticated users can also look up their own NFTs.

In your dApp, there is no login/password combination or Identity Provider (IdP) in place to authenticate your users. Instead, users connect their digital wallet to the web application.

To capture users’ wallet addresses and grant them temporary AWS credentials, you can use Amazon Cognito user pool and Amazon Cognito identity pool.

You can create a custom authentication flow by implementing an Amazon Cognito custom authentication challenge, which uses AWS Lambda triggers. This challenge requires your users to sign a generated message using their digital wallet. If the signature is valid, it confirms that the user owns this wallet address. The wallet address is then used as a user identifier in the Amazon Cognito user pool.

Figure 2 details the Amazon Cognito authentication process. Three Lambda functions are used to perform the different authentication steps.

Amazon Cognito authentication process

Figure 2. Amazon Cognito authentication process

  1. To define the authentication success conditions, the Amazon Cognito user pool calls the “Define auth challenge” Lambda function (defineAuthChallenge.js).
  2. To generate the challenge, Amazon Cognito calls the “Create auth challenge” Lambda function (createAuthChallenge.js). In this case, it generates a random message for the user to sign. Amazon Cognito forwards the challenge to the dApp, which prompts the user to sign the message using their digital wallet and private key. The dApp then returns the signature to Amazon Cognito as a response.
  3. To verify if the user’s wallet effectively signed the message, Amazon Cognito forwards the user’s response to the “Verify auth challenge response” Lambda function (verifyAuthChallengeResponse.js). If True, then Amazon Cognito authenticates the user and creates a new identity in the user pool with the wallet address as username.
  4. Finally, Amazon Cognito returns a JWT Token to the dApp containing multiple claims, one of them being cognito:username, which contains the user’s wallet address. These claims will be passed to your AWS Lambda event and Amazon API Gateway mapping templates allowing your backend to securely identify the user making those API requests.

Authorization

Amazon API Gateway offers multiple ways of authorizing access to an API route. This example showcases three different authorization methods:

  • AWS_IAM: Authorization with IAM Roles. IAM roles grant access to specific API routes or any other AWS resources. The IAM Role assumed by the user is granted by Amazon Cognito identity pool.
  • COGNITO_USER_POOLS: Authorization with Amazon Cognito user pool. API routes are protected by validating the user’s Amazon Cognito token.
  • NONE: No authorization. API routes are open to the public internet.

API Gateway backend integrations

HTTP proxy integration

The HTTP proxy integration method allows you to proxy HTTP requests to another API. The requests and responses can passthrough as-is, or you can modify them on the fly using Mapping Templates.

This method is a cost-effective way to secure access to any third-party API. This is because your third-party API keys are stored in your API Gateway and not on the frontend application.

You can also activate caching on API Gateway to reduce the amount of API calls made to the backend APIs. This will increase performance, reduce cost, and control usage.

Inspect the GetNFTsMoralisGETMethod and GetNFTsAlchemyGETMethod resources in the SAM template to understand how you can use Mapping Templates to modify the headers, path, or query string of your incoming requests.

Lambda proxy integration

API Gateway can use AWS Lambda as backend integration. Lambda functions enable you to implement custom code and logic before returning a response to your dApp.

In the backend/src folder, you will find two Lambda functions:

  • getNFTsMoralisLambda.js: Calls Moralis API and returns raw response
  • getNFTsAlchemyLambda.js: Calls Alchemy API and returns raw response

To access your authenticated user’s wallet address from your Lambda function code, access the cognito:username claim as follows:

var wallet_address = event.requestContext.authorizer.claims["cognito:username"];

Using Amplify Libraries in the dApp

The dApp uses the AWS Amplify Javascript Libraries to interact with Amazon Cognito user pool, Amazon Cognito identity pool, and Amazon API Gateway.

With Amplify Libraries, you can interact with the Amazon Cognito custom authentication flow, get AWS credentials for your frontend, and make HTTP API calls to your API Gateway endpoint.

The Amplify Auth library is used to perform the authentication flow. To sign up, sign in, and respond to the Amazon Cognito custom challenge, use the Amplify Auth library. Examine the ConnectButton.js and user.js files in the dapp folder.

To make API calls to your API Gateway, you can use the Amplify API library. Examine the api.js file in the dApp to understand how you can make API calls to different API routes. Note that some are protected by AWS_IAM authorization and others by COGNITO_USER_POOL.

Based on the current authentication status, your users will automatically assume the CognitoAuthorizedRole or CognitoUnAuthorizedRole IAM Roles referenced in the Amazon Cognito identity pool. AWS Amplify will automatically use the credentials associated with your AWS IAM Role when calling an API route protected by the AWS_IAM authorization method.

Amazon Cognito identity pool allows anonymous users to assume the CognitoUnAuthorizedRole IAM Role. This allows secure access to your API routes or any other AWS services you configured, even for your anonymous users. Your API routes will then not be publicly available to the internet.

Cleaning up

To avoid incurring future charges, delete the CloudFormation stack created by SAM. Run the sam delete command or delete the CloudFormation stack in the AWS Management Console directly.

Conclusion

In this blog, we’ve demonstrated how to use different AWS managed services to run and deploy a decentralized web application (dApp) on AWS. We’ve also shown how to integrate securely with Web3 providers’ APIs, like Alchemy or Moralis.

You can use Amazon Cognito user pool to create a custom authentication challenge and authenticate users using a cryptographically signed message. And you can secure access to third-party APIs, using API Gateway and keep your secrets safe on the backend.

Finally, you’ve seen how to host a single-page application (SPA) using Amazon S3 and Amazon CloudFront as your content delivery network (CDN).

How to monitor the expiration of SAML identity provider certificates in an Amazon Cognito user pool

Post Syndicated from Karthik Nagarajan original https://aws.amazon.com/blogs/security/how-to-monitor-the-expiration-of-saml-identity-provider-certificates-in-an-amazon-cognito-user-pool/

With Amazon Cognito user pools, you can configure third-party SAML identity providers (IdPs) so that users can log in by using the IdP credentials. The Amazon Cognito user pool manages the federation and handling of tokens returned by a configured SAML IdP. It uses the public certificate of the SAML IdP to verify the signature in the SAML assertion returned by the IdP. Public certificates have an expiry date, and an expired public certificate will result in a SAML user federation failing because it can no longer be used for signature verification. To avoid user authentication failures, you must monitor and rotate SAML public certificates before expiration.

You can configure SAML IdPs in an Amazon Cognito user pool by using a SAML metadata document or a URL that points to the metadata document. If you use the SAML metadata document option, you must manually upload the SAML metadata. If you use the URL option, Amazon Cognito downloads the metadata from the URL and automatically configures the SAML IdP. In either scenario, if you don’t rotate the SAML certificate before expiration, users can’t log in using that SAML IdP.

In this blog post, I will show you how to monitor SAML certificates that are about to expire or already expired in an Amazon Cognito user pool by using an AWS Lambda function initiated by an Amazon EventBridge rule.

Solution overview

In this section, you will learn how to configure a Lambda function that checks the validity period of the SAML IdP certificates in an Amazon Cognito user pool, logs the findings to AWS Security Hub, and sends out an Amazon Simple Notification Service (Amazon SNS) notification with the list of certificates that are about to expire or have already expired. This Lambda function is invoked by an EventBridge rule that uses a rate or cron expression and runs on a defined schedule. For example, if the rate expression is defined as 1 day, the EventBridge rule initiates the Lambda function once each day. Figure 1 shows an overview of this process.

Figure 1: Lambda function initiated by EventBridge rule

Figure 1: Lambda function initiated by EventBridge rule

As shown in Figure 1, this process involves the following steps:

  1. EventBridge runs a rule using a rate expression or cron expression and invokes the Lambda function.
  2. The Lambda function performs the following tasks:
    1. Gets the list of SAML IdPs and corresponding X509 certificates.
    2. Verifies if the X509 certificates are about to expire or already expired based on the dates in the certificate.
  3. Based on the results of step 2, the Lambda function logs the findings in AWS Security Hub. Each finding shows the SAML certificate that is about to expire or is already expired.
  4. Based on the results of step 2, the Lambda function publishes a notification to the Amazon SNS topic with the certificate expiration details. For example, if CERT_EXPIRY_DAYS=60, the details of SAML certificates that are going to expire within 60 days or are already expired are published in the SNS notification.
  5. Amazon SNS sends messages to the subscribers of the topic, such as an email address.

Prerequisites

For this setup, you will need to have the following in place:

Implementation details

In this section, we will walk you through how to deploy the Lambda function and configure an EventBridge rule that invokes the Lambda function.

Step 1: Create the Node.js Lambda package

  1. Open a command line terminal or shell.
  2. Create a folder named saml-certificate-expiration-monitoring.
  3. Install the fast-xml-parser module by running the following command:
    cd saml-certificate-expiration-monitoring
    npm install fast-xml-parser
  4. Create a file named index.js and paste the following content in the file.
    const AWS = require('aws-sdk');
    const { X509Certificate } = require('crypto');
    const { XMLParser} = require("fast-xml-parser");
    const https = require('https');
    
    exports.handler = async function(event, context, callback) {
      
        const cognitoUPID = process.env.COGNITO_UPID;
        const expiryDays = process.env.CERT_EXPIRY_DAYS;
        const snsTopic = process.env.SNS_TOPIC_ARN;
        const postToSh = process.env.ENABLE_SH_MONITORING; //Enable security hub monitoring
        var securityhub = new AWS.SecurityHub({apiVersion: '2018-10-26'});
        
        var shParams = {
          Findings: []
        };
    
        AWS.config.apiVersions = {
          cognitoidentityserviceprovider: '2016-04-18',
        };
    
        // Initialize CognitoIdentityServiceProvider.
        const cognitoidentityserviceprovider = new AWS.CognitoIdentityServiceProvider();
    
        let listProvidersParams = {
          UserPoolId: cognitoUPID /* required */
        };
        
        let hasNext = true;
        const providerNames = [];
        
        while (hasNext) {
          const listProvidersResp = await cognitoidentityserviceprovider.listIdentityProviders(listProvidersParams).promise();
          listProvidersResp['Providers'].forEach(function(provider) {
                if(provider.ProviderType == 'SAML') {
                  providerNames.push(provider.ProviderName);
                }
            });
          
          listProvidersParams.NextToken = listProvidersResp.NextToken;
          hasNext = !!listProvidersResp.NextToken; //Keep iterating if there are more pages
        }
     
        let describeIdentityProviderParams = {
          UserPoolId: cognitoUPID /* required */
        };
        
        //Initialize the options for fast-xml-parser  
        //Parse KeyDescriptor as an array
        const alwaysArray = [
          "EntityDescriptor.IDPSSODescriptor.KeyDescriptor"
        ];
        const options = {
          removeNSPrefix: true,
          isArray: (name, jpath, isLeafNode, isAttribute) => { 
            if( alwaysArray.indexOf(jpath) !== -1) return true;
          },
          ignoreDeclaration: true
        };
        const parser = new XMLParser(options);
        
        let certExpMessage = '';
        const today = new Date();
        
        if(providerNames.length == 0) {
          console.log("There are no SAML providers in this Cognito user pool. ID : " + cognitoUPID);
        }
        
        for (let provider of providerNames) {
          describeIdentityProviderParams.ProviderName = provider;
          const descProviderResp = await cognitoidentityserviceprovider.describeIdentityProvider(describeIdentityProviderParams).promise();
          let xml = '';
          //Read SAML metadata from Cognito if the file is available. Else, read the SAML metadata from URL
          if('MetadataFile' in descProviderResp.IdentityProvider.ProviderDetails) {
            xml = descProviderResp.IdentityProvider.ProviderDetails.MetadataFile;
          } else {
            let metadata_promise = getMetadata(descProviderResp.IdentityProvider.ProviderDetails.MetadataURL);
    		    xml = await metadata_promise;
          }
          let jObj = parser.parse(xml);
          if('EntityDescriptor' in jObj) {
            //SAML metadata can have multiple certificates for signature verification. 
            for (let cert of jObj['EntityDescriptor']['IDPSSODescriptor']['KeyDescriptor']) {
              let certificate = '-----BEGIN CERTIFICATE-----\n' 
              + cert['KeyInfo']['X509Data']['X509Certificate'] 
              + '\n-----END CERTIFICATE-----';
              let x509cert = new X509Certificate(certificate);
              console.log("------ Provider : " + provider + "-------");
              console.log("Cert Expiry: " + x509cert.validTo);
              const diffTime = Math.abs(new Date(x509cert.validTo) - today);
              const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24));
              console.log("Days Remaining: " + diffDays);
              if(diffDays <= expiryDays) {
                
                certExpMessage += 'Provider name: ' + provider + ' SAML certificate (serialnumber : '+ x509cert.serialNumber + ') expiring in ' + diffDays + ' days \n';
                
                if(postToSh === 'true') {
                  //Log finding for security hub
                  logFindingToSh(context, shParams,
                  'Provider name: ' + provider + ' SAML certificate is expiring in ' + diffDays + ' days. Please contact the Identity provider to rotate the certificate.',
                  x509cert.fingerprint, cognitoUPID, provider); 
                }
              }
            }
          }
        }
        //Send a SNS message if a certificate is about to expire or already expired
        if(certExpMessage) {
          console.log("SAML certificates expiring within next " + expiryDays + " days :\n");
          console.log(certExpMessage);
          certExpMessage = "SAML certificates expiring within next " + expiryDays + " days :\n" + certExpMessage;
          // Create publish parameters
          let snsParams = {
            Message: certExpMessage, /* required */
            TopicArn: snsTopic
          };
          // Create promise and SNS service object
          let publishTextPromise = await new AWS.SNS({apiVersion: '2010-03-31'}).publish(snsParams).promise();
          console.log(publishTextPromise);
          
          if(postToSh === 'true') {
            console.log("Posting the finding to SecurityHub");
            let shPromise = await securityhub.batchImportFindings(shParams).promise();
            console.log("shPromise : " + JSON.stringify(shPromise));
          }
          
        } else {
          console.log("No certificates are expiring within " + expiryDays + " days");
        }
    };
    
    function getMetadata(url) {
    	return new Promise((resolve, reject) => {
    		https.get(url, (response) => {
    			let chunks_of_data = [];
    
    			response.on('data', (fragments) => {
    				chunks_of_data.push(fragments);
    			});
    
    			response.on('end', () => {
    				let response_body = Buffer.concat(chunks_of_data);
    				resolve(response_body.toString());
    			});
    
    			response.on('error', (error) => {
    				reject(error);
    			});
    		});
    	});
    }
    
    function logFindingToSh(context, shParams, remediationMsg, certFp, cognitoUPID, provider) {
      const accountID = context.invokedFunctionArn.split(':')[4];
      const region = process.env.AWS_REGION;
      const sh_product_arn = `arn:aws:securityhub:${region}:${accountID}:product/${accountID}/default`;
      const today = new Date().toISOString();
      
      shParams.Findings.push(
            {
          SchemaVersion: "2018-10-08",
          AwsAccountId: `${accountID}`, /* required */
          CreatedAt: `${today}`, /* required */
          UpdatedAt: `${today}`,
          Title: 'SAML Certificate expiration',
          Description: 'SAML certificate expiry', /* required */
          GeneratorId: `${context.invokedFunctionArn}`, /* required */
          Id: `${cognitoUPID}:${provider}:${certFp}`, /* required */
          ProductArn: `${sh_product_arn}`, /* required */
          Severity: {
              Original: '89.0',
              Label: 'HIGH'
          },
          Types: [
                    "Software and Configuration Checks/AWS Config Analysis"
          ],
          Compliance: {Status: 'WARNING'},
          Resources: [ /* required */
            {
              Id: `${cognitoUPID}`, /* required */
              Type: 'AWSCognitoUserPool', /* required */
              Region: `${region}`,
              Details : {
                Other: { 
                           "IdPIdentifier" : `${provider}` 
                }
              }
            }
          ],
          Remediation: {
                    Recommendation: {
                        Text: `${remediationMsg}`,
                        Url: `https://console.aws.amazon.com/cognito/v2/idp/user-pools/${cognitoUPID}/sign-in/identity-providers/details/${provider}`
                    }
          }
        }
      );
    }
  5. To create the deployment package for a .zip file archive, you can use a built-in .zip file archive utility or other third-party zip file utility. If you are using Linux or Mac OS, run the following command.
    zip -r saml-certificate-expiration-monitoring.zip .

Step 2: Create an Amazon SNS topic

  1. Create a standard Amazon SNS topic named saml-certificate-expiration-monitoring-topic for the Lambda function to use to send out notifications, as described in Creating an Amazon SNS topic.
  2. Copy the Amazon Resource Name (ARN) for Amazon SNS. Later in this post, you will use this ARN in the AWS Identity and Access Management (IAM) policy and Lambda environment variable configuration.
  3. After you create the Amazon SNS topic, create email subscribers to this topic.

Step 3: Configure the IAM role and policies and deploy the Lambda function

  1. In the IAM documentation, review the section Creating policies on the JSON tab. Then, using those instructions, use the following template to create an IAM policy named lambda-saml-certificate-expiration-monitoring-function-policy for the Lambda role to use. Replace <REGION> with your Region, <AWS-ACCT-NUMBER> with your AWS account ID, <SNS-ARN> with the Amazon SNS ARN from Step 2: Create an Amazon SNS topic, and <USER_POOL_ID> with your Amazon Cognito user pool ID that you want to monitor.
    {
        "Version": "2012-10-17",
        "Statement": [
            {
                "Sid": "AllowLambdaToCreateGroup",
                "Effect": "Allow",
                "Action": "logs:CreateLogGroup",
                "Resource": "arn:aws:logs:<REGION>:<AWS-ACCT-NUMBER>:*"
            },
            {
                "Sid": "AllowLambdaToPutLogs",
                "Effect": "Allow",
                "Action": [
                    "logs:CreateLogStream",
                    "logs:PutLogEvents"
                ],
                "Resource": [
                    "arn:aws:logs:<REGION>:<AWS-ACCT-NUMBER>:log-group:/aws/lambda/saml-certificate-expiration-monitoring:*"
                ]
            },
            {
                "Sid": "AllowLambdaToGetCognitoIDPDetails",
                "Effect": "Allow",
                "Action": [
                    "cognito-idp:DescribeIdentityProvider",
                    "cognito-idp:ListIdentityProviders",
                    "cognito-idp:GetIdentityProviderByIdentifier"
                ],
                "Resource": "arn:aws:cognito-idp:<REGION>:<AWS-ACCT-NUMBER>:userpool/<USER_POOL_ID>"
            },
            {
                "Sid": "AllowLambdaToPublishToSNS",
                "Effect": "Allow",
                "Action": "SNS:Publish",
                "Resource": "<SNS-ARN>"
            } ,
            {
                "Sid": "AllowLambdaToPublishToSecurityHub",
                "Effect": "Allow",
                "Action": [
                    "SecurityHub:BatchImportFindings"
                ],
                "Resource": "arn:aws:securityhub:<REGION>:<AWS-ACCT-NUMBER>:product/<AWS-ACCT-NUMBER>/default"
            }
        ]
    }

  2. After the policy is created, create a role for the Lambda function to use the policy, by following the instructions in Creating a role to delegate permissions to an AWS service. Choose Lambda as the service to assume the role and attach the policy lambda-saml-certificate-expiration-monitoring-function-policy that you created in step 1 of this section. Specify a role named lambda-saml-certificate-expiration-monitoring-function-role, and then create the role.
  3. Review the topic Create a Lambda function with the console within the Lambda documentation. Then create the Lambda function, choosing the following options:
    1. Under Create function, choose Author from scratch to create the function.
    2. For the function name, enter saml-certificate-expiration-monitoring, and for Runtime, choose Node.js 16.x.
    3. For Execution role, expand Change default execution role, select Use an existing role, and select the role created in step 2 of this section.
    4. Choose Create function to open the Designer, and upload the zip file that was created in Step 1: Create the Node.js Lambda package.
    5. You should see the index.js code in the Lambda console.
  4. After the Lambda function is created, you will need to adjust the timeout duration. Set the Lambda timeout to 10 seconds. For more information, see the timeout entry in Configuring functions in the console. If you receive a timeout error, see How do I troubleshoot Lambda function invocation timeout errors?
  5. If you make code changes after uploading, deploy the Lambda function.

Step 4: Create an EventBridge rule

  1. Follow the instructions in creating an Amazon EventBridge rule that runs on a schedule to create a rule named saml-certificate-expiration-monitoring-rule. You can use a rate expression of 24 hours to initiate the event. This rule will invoke the Lambda function once per day.
  2. For Select a target, choose AWS Lambda service.
  3. For Lambda function, select the saml-certificate-expiration-monitoring function that you deployed in Step 3: Configure the IAM role and policies and deploy the Lambda function.

Step 5: Test the Lambda function

  1. Open the Lambda console, select the function that you created earlier, and configure the following environment variables:
    1. Create an environment variable called CERT_EXPIRY_DAYS. This specifies how much lead time, in days, you want to have before the certificate expiration notification is sent.
    2. Create an environment variable called COGNITO_UPID. This identifies the Amazon Cognito user pool ID that needs to be monitored.
    3. Create an environment variable called SNS_TOPIC_ARN and set it to the Amazon SNS topic ARN from Step 2: Create an Amazon SNS topic.
    4. Create an environment variable called ENABLE_SH_MONITORING and set it to true or false. If you set it to true, the Lambda function will log the findings in AWS Security Hub.
  2. Configure a test event for the Lambda function by using the default template and name it TC1, as shown in Figure 2.
    Figure 2: Create a Lambda test case

    Figure 2: Create a Lambda test case

  3. Run the TC1 test case to test the Lambda function. To make sure that the Lambda function ran successfully, check the Amazon CloudWatch logs. You should see the console log messages from the Lambda function. If ENABLE_SH_MONITORING is set to true in the Lambda environment variables, you will see a list of findings in AWS Security Hub for certificates with an expiry of less than or equal to the value of the CERT_EXPIRY_DAYS environment variable. Also, an email will be sent to each subscriber of the Amazon SNS topic.

Cleanup

To avoid future charges, delete the following resources used in this post (if you don’t need them) and disable AWS Security Hub.

  • Lambda function
  • EventBridge rule
  • CloudWatch logs associated with the Lambda function
  • Amazon SNS topic
  • IAM role and policy that you created for the Lambda function

Conclusion

An Amazon Cognito user pool with hundreds of SAML IdPs can be challenging to monitor. If a SAML IdP certificate expires, users can’t log in using that SAML IdP. This post provides the steps to monitor your SAML IdP certificates and send an alert to Amazon Cognito user pool administrators when a certificate is about to expire so that you can proactively work with your SAML IdP administrator to rotate the certificate. Now that you’ve learned the benefits of monitoring your IdP certificates for expiration, I recommend that you implement these, or similar, controls to make sure that you’re notified of these events before they occur.

If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, start a new thread on the Amazon Cognito re:Post or contact AWS Support.

Want more AWS Security news? Follow us on Twitter.

Karthik Nagarajan

Karthik Nagarajan

Karthik is Security Engineer with AWS Identity Security Team. He helps the Amazon Cognito team to build a secure product for the customers.

How Novo Nordisk built distributed data governance and control at scale

Post Syndicated from Jonatan Selsing original https://aws.amazon.com/blogs/big-data/how-novo-nordisk-built-distributed-data-governance-and-control-at-scale/

This is a guest post co-written with Jonatan Selsing and Moses Arthur from Novo Nordisk.

This is the second post of a three-part series detailing how Novo Nordisk, a large pharmaceutical enterprise, partnered with AWS Professional Services to build a scalable and secure data and analytics platform. The first post of this series describes the overall architecture and how Novo Nordisk built a decentralized data mesh architecture, including Amazon Athena as the data query engine. The third post will show how end-users can consume data from their tool of choice, without compromising data governance. This will include how to configure Okta, AWS Lake Formation, and a business intelligence tool to enable SAML-based federated use of Athena for an enterprise BI activity.

When building a scalable data architecture on AWS, giving autonomy and ownership to the data domains are crucial for the success of the platform. By providing the right mix of freedom and control to those people with the business domain knowledge, your business can maximize value from the data as quickly and effectively as possible. The challenge facing organizations, however, is how to provide the right balance between freedom and control. At the same time, data is a strategic asset that needs to be protected with the highest degree of rigor. How can organizations strike the right balance between freedom and control?

In this post, you will learn how to build decentralized governance with Lake Formation and AWS Identity and Access Management (IAM) using attribute-based access control (ABAC). We discuss some of the patterns we use, including Amazon Cognito identity pool federation using ABAC in permission policies, and Okta-based SAML federation with ABAC enforcement on role trust policies.

Solution overview

In the first post of this series, we explained how Novo Nordisk and AWS Professional Services built a modern data architecture based on data mesh tenets. This architecture enables data governance on distributed data domains, using an end-to-end solution to create data products and providing federated data access control. This post dives into three elements of the solution:

  • How IAM roles and Lake Formation are used to manage data access across data domains
  • How data access control is enforced at scale, using a group membership mapping with an ABAC pattern
  • How the system maintains state across the different layers, so that the ecosystem of trust is configured appropriately

From the end-user perspective, the objective of the mechanisms described in this post is to enable simplified data access from the different analytics services adopted by Novo Nordisk, such as those provided by software as a service (SaaS) vendors like Databricks, or self-hosted ones such as JupyterHub. At the same time, the platform must guarantee that any change in a dataset is immediately reflected at the service user interface. The following figure illustrates at a high level the expected behavior.

High-level data platform expected behavior

Following the layer nomenclature established in the first post, the services are created and managed in the consumption layer. The domain accounts are created and managed in the data management layer. Because changes can occur from both layers, continuous communication in both directions is required. The state information is kept in the virtualization layer along with the communication protocols. Additionally, at sign-in time, the services need information about data resources required to provide data access abstraction.

Managing data access

The data access control in this architecture is designed around the core principle that all access is encapsulated in isolated IAM role sessions. The layer pattern that we described in the first post ensures that the creation and curation of the IAM role policies involved can be delegated to the different data management ecosystems. Each data management platform integrated can use their own data access mechanisms, with the unique requirement that the data is accessed via specific IAM roles.

To illustrate the potential mechanisms that can be used by data management solutions, we show two examples of data access permission mechanisms used by two different data management solutions. Both systems utilize the same trust policies as described in the following sections, but have a completely different permission space.

Example 1: Identity-based ABAC policies

The first mechanism we discuss is an ABAC role that provides access to a home-like data storage area, where users can share within their departments and with the wider organization in a structure that mimics the organizational structure. Here, we don’t utilize the group names, but instead forward user attributes from the corporate Active Directory directly into the permission policy through claim overrides. We do this by having the corporate Active Directory as the identity provider (IdP) for the Amazon Cognito user pool and mapping the relevant IdP attributes to user pool attributes. Then, in the Amazon Cognito identity pool, we map the user pool attributes to session tags to use them for access control. Custom overrides can be included in the claim mapping, through the use of a pre token generation Lambda trigger. This way, claims from AD can be mapped to Amazon Cognito user pool attributes and then ultimately used in the Amazon Cognito identity pool to control IAM role permissions. The following is an example of an IAM policy with sessions tags:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Condition": {
                "StringLike": {
                    "s3:prefix": [
                        "",
                        "public/",
                        "public/*",
                        "home/",
                        "home/${aws:PrincipalTag/initials}/*",
                        "home/${aws:PrincipalTag/department}/*"
                    ]
                }
            },
            "Action": "s3:ListBucket",
            "Resource": [
                "arn:aws:s3:::your-home-bucket"
            ],
            "Effect": "Allow"
        },
        {
            "Action": [
                "s3:GetObject*",
                "s3:PutObject*",
                "s3:DeleteObject*"
            ],
            "Resource": [
                "arn:aws:s3:::your-home-bucket/home/${aws:PrincipalTag/initials}",
                "arn:aws:s3:::your-home-bucket/home/${aws:PrincipalTag/initials}/*",
                "arn:aws:s3:::your-home-bucket/public/${aws:PrincipalTag/initials}",
                "arn:aws:s3:::your-home-bucket/public/${aws:PrincipalTag/initials}/*",
                "arn:aws:s3:::your-home-bucket/home/${aws:PrincipalTag/department}",
                "arn:aws:s3:::your-home-bucket/home/${aws:PrincipalTag/department}/*",
                "arn:aws:s3:::your-home-bucket/public/${aws:PrincipalTag/department}",
                "arn:aws:s3:::your-home-bucket/public/${aws:PrincipalTag/department}/*"
            ],
            "Effect": "Allow"
        },
        {
            "Action": "s3:GetObject*",
            "Resource": [
                "arn:aws:s3:::your-home-bucket/public/",
                "arn:aws:s3:::your-home-bucket/public/*"
            ],
            "Effect": "Allow"
        }
    ]
}

This role is then embedded in the analytics layer (together with the data domain roles) and assumed on behalf of the user. This enables users to mix and match between data domains—as well as utilizing private and public data paths that aren’t necessarily tied to any data domain. For more examples of how ABAC can be used with permission policies, refer to How to scale your authorization needs by using attribute-based access control with S3.

Example 2: Lake Formation name-based access controls

In the data management solution named Novo Nordisk Enterprise Datahub (NNEDH), which we introduced in the first post, we use Lake Formation to enable standardized data access. The NNEDH datasets are registered in the Lake Formation Data Catalog as databases and tables, and permissions are granted using the named resource method. The following screenshot shows an example of these permissions.

Lakeformation named resource method for permissions management

In this approach, data access governance is delegated to Lake Formation. Every data domain in NNEDH has isolated permissions synthesized by NNEDH as the central governance management layer. This is a similar pattern to what is adopted for other domain-oriented data management solutions. Refer to Use an event-driven architecture to build a data mesh on AWS for an example of tag-based access control in Lake Formation.

These patterns don’t exclude implementations of peer-to-peer type data sharing mechanisms, such as those that can be achieved using AWS Resource Access Manager (AWS RAM), where a single IAM role session can have permissions that span across accounts.

Delegating role access to the consumption later

The following figure illustrates the data access workflow from an external service.

Data access workflow from external service

The workflow steps are as follows:

  1. A user authenticates on an IdP used by the analytics tool that they are trying to access. A wide range of analytics tools are supported by Novo Nordisk platform, such as Databricks and JupyterHub, and the IdP can be either SAML or OIDC type depending on the capabilities of the third-party tool. In this example, an Okta SAML application is used to sign into a third-party analytics tool, and an IAM SAML IdP is configured in the data domain AWS account to federate with the external IdP. The third post of this series describes how to set up an Okta SAML application for IAM role federation on Athena.
  2. The SAML assertion obtained during the sign-in process is used to request temporary security credentials of an IAM role through the AssumeRole operation. In this example, the SAML assertion is used onAssumeRoleWithSAMLoperation. For OpenID Connect-compatible IdPs, the operationAssumeRoleWithWebIdentitymust be used with the JWT. The SAML attributes in the assertion or the claims in the token can be generated at sign-in time, to ensure that the group memberships are forwarded, for the ABAC policy pattern described in the following sections.
  3. The analytics tool, such as Databricks or JupyterHub, abstracts the usage of the IAM role session credentials in the tool itself, and data can be accessed directly according to the permissions of the IAM role assumed. This pattern is similar in nature to IAM passthrough as implemented by Databricks, but in Novo Nordisk it’s extended across all analytics services. In this example, the analytics tool accesses the data lake on Amazon Simple Storage Service (Amazon S3) through Athena queries.

As the data mesh pattern expands across domains covering more downstream services, we need a mechanism to keep IdPs and IAM role trusts continuously updated. We come back to this part later in the post, but first we explain how role access is managed at scale.

Attribute-based trust policies

In previous sections, we emphasized that this architecture relies on IAM roles for data access control. Each data management platform can implement its own data access control method using IAM roles, such as identity-based policies or Lake Formation access control. For data consumption, it’s crucial that these IAM roles are only assumable by users that are part of Active Directory groups with the appropriate entitlements to use the role. To implement this at scale, the IAM role’s trust policy uses ABAC.

When a user authenticates on the external IdP of the consumption layer, we add in the access token a claim derived from their Active Directory groups. This claim is propagated by theAssumeRoleoperation into the trust policy of the IAM role, where it is compared with the expected Active Directory group. Only users that belong to the expected groups can assume the role. This mechanism is illustrated in the following figure.

Architecture of the integration with the identity provider

Translating group membership to attributes

To enforce the group membership entitlement at the role assumption level, we need a way to compare the required group membership with the group memberships that a user comes with in their IAM role session. To achieve this, we use a form of ABAC, where we have a way to represent the sum of context-relevant group memberships in a single attribute. A single IAM role session tag value is limited to 256 characters. The corresponding limit for SAML assertions is 100,000 characters, so for systems where a very large number of either roles or group-type mappings are required, SAML can support a wider range of configurations.

In our case, we have opted for a compression algorithm that takes a group name and compresses it to a 4-character string hash. This means that, together with a group-separation character, we can fit 51 groups in a single attribute. This gets pushed down to approximately 20 groups for OIDC type role assumption due to the PackedPolicySize, but is higher for a SAML-based flow. This has shown to be sufficient for our case. There is a risk that two different groups could hash to the same character combination; however, we have checked that there are no collisions in the existing groups. To mitigate this risk going forward, we have introduced guardrails in multiples places. First, before adding new groups entitlements in the virtualization layer, we check if there’s a hash collision with any existing group. When a duplicated group is attempted to be added, our service team is notified and we can react accordingly. But as stated earlier, there is a low probability of clashes, so the flexibility this provides outweighs the overhead associated with managing clashes (we have not had any yet). We additionally enforce this at SAML assertion creation time as well, to ensure that there are no duplicated groups in the users group list, and in cases of duplication, we remove both entirely. This means malicious actors can at most limit the access of other users, but not gain unauthorized access.

Enforcing audit functionality across sessions

As mentioned in the first post, on top of governance, there are strict requirements around auditability of data accesses. This means that for all data access requests, it must be possible to trace the specific user across services and retain this information. We achieve this by setting (and enforcing) a source identity for all role sessions and make sure to propagate enterprise identity to this attribute. We use a combination of Okta inline hooks and SAML session tags to achieve this. This means that the AWS CloudTrail logs for an IAM role session have the following information:

{
    "eventName": "AssumeRoleWithSAML",
    "requestParameters": {
        "SAMLAssertionlD": "id1111111111111111111111111",
        "roleSessionName": "[email protected]",
        "principalTags": {
            "nn-initials": "user",
            "department": "NNDepartment",
            "GroupHash": "xxxx",
            "email": "[email protected]",
            "cost-center": "9999"
        },
        "sourceIdentity": "[email protected]",
        "roleArn": "arn:aws:iam::111111111111:role/your-assumed-role",
        "principalArn": "arn:aws:iam,111111111111:saml-provider/your-saml-provider",
        ...
    },
    ...
}

On the IAM role level, we can enforce the required attribute configuration with the following example trust policy. This is an example for a SAML-based app. We support the same patterns through OpenID Connect IdPs.

We now go through the elements of an IAM role trust policy, based on the following example:

{
    "Version": "2008-10-17",
    "Statement": {
        "Effect": "Allow",
        "Principal": {
            "Federated": [SAML_IdP_ARN]
        },
        "Action": [
            "sts:AssumeRoleWithSAML",
            "sts:TagSession",
            "sts:SetSourceIdentity"
        ],
        "Condition": {
            "StringEquals": {
                "SAML:aud": "https://signin.aws.amazon.com/saml"
            },
            "StringLike": {
                "sts:SourceIdentity": "*@novonordisk.com",
                "aws:RequestTag/GroupHash": ["*xxxx*"]
            },
            "StringNotLike": {
                "sts:SourceIdentity": "*"
            }
        }
    }
}

The policy contains the following details:

  • ThePrincipalstatement should point to the list of apps that are served through the consumption layer. These can be Azure app registrations, Okta apps, or Amazon Cognito app clients. This means that SAML assertions (in the case of SAML-based flows) minted from these applications can be used to run the operationAssumeRoleWithSamlif the remaining elements are also satisfied.
  • TheActionstatement includes the required permissions for theAssumeRolecall to succeed, including adding the contextual information to the role session.
  • In the first condition, the audience of the assertion needs to be targeting AWS.
  • In the second condition, there are twoStringLikerequirements:
    • A requirement on the source identity as the naming convention to follow at Novo Nordisk (users must come with enterprise identity, following our audit requirements).
    • Theaws:RequestTag/GroupHashneeds to bexxxx, which represents the hashed group name mentioned in the upper section.
  • Lastly, we enforce that sessions can’t be started without setting the source identity.

This policy enforces that all calls are from recognized services, include auditability, have the right target, and enforces that the user has the right group memberships.

Building a central overview of governance and trust

In this section, we discuss how Novo Nordisk keeps track of the relevant group-role relations and maps these at sign-in time.

Entitlements

In Novo Nordisk, all accesses are based on Active Directory group memberships. There is no user-based access. Because this pattern is so central, we have extended this access philosophy into our data accesses. As mentioned earlier, at sign-in time, the hooks need to be able to know which roles to assume for a given user, given this user’s group membership. We have modeled this data in Amazon DynamoDB, where just-in-time provisioning ensures that only the required user group memberships are available. By building our application around the use of groups, and by having the group propagation done by the application code, we avoid having to make a more general Active Directory integration, which would, for a company the size of Novo Nordisk, severely impact the application, simply due to the volume of users and groups.

The DynamoDB entitlement table contains all relevant information for all roles and services, including role ARNs and IdP ARNs. This means that when users log in to their analytics services, the sign-in hook can construct the required information for the Roles SAML attribute.

When new data domains are added to the data management layer, the data management layer needs to communicate both the role information and the group name that gives access to the role.

Single sign-on hub for analytics services

When scaling this permission model and data management pattern to a large enterprise such as Novo Nordisk, we ended up creating a large number of IAM roles distributed across different accounts. Then, a solution is required to map and provide access for end-users to the required IAM role. To simplify user access to multiple data sources and analytics tools, Novo Nordisk developed a single sign-on hub for analytics services. From the end-user perspective, this is a web interface that glues together different offerings in a unified system, making it a one-stop tool for data and analytics needs. When signing in to each of the analytical offerings, the authenticated sessions are forwarded, so users never have to reauthenticate.

Common for all the services supported in the consumption layer is that we can run a piece of application code at sign-in time, allowing sign-in time permissions to be calculated. The hooks that achieve this functionality can, for instance, be run by Okta inline hooks. This means that each of the target analytics services can have custom code to translate relevant contextual information or provide other types of automations for the role forwarding.

The sign-in flow is demonstrated in the following figure.

Sign-in flow

The workflow steps are as follows:

  1. A user accesses an analytical service such as Databricks in the Novo Nordisk analytics hub.
  2. The service uses Okta as the SAML-based IdP.
  3. Okta invokes an AWS Lambda-based SAML assertion inline hook.
  4. The hook uses the entitlement database, converting application-relevant group memberships into role entitlements.
  5. Relevant contextual information is returned from the entitlement database.
  6. The Lambda-based hook adds new SAML attributes to the SAML assertion, including the hashed group memberships and other contextual information such as source identity.
  7. A modified SAML assertion is used to sign users in to the analytical service.
  8. The user can now use the analytical tool with active IAM role sessions.

Synchronizing role trust

The preceding section gives an overview of how federation works in this solution. Now we can go through how we ensure that all participating AWS environments and accounts are in sync with the latest configuration.

From the end-user perspective, the synchronization mechanism must ensure that every analytics service instantiated can access the data domains assigned to the groups that the user belongs to. Also, changes in data domains—such as granting data access to an Active Directory group—must be effective immediately to every analytics service.

Two event-based mechanisms are used to maintain all the layers synchronized, as detailed in this section.

Synchronize data access control on the data management layer with changes to services in the consumption layer

As describe in the previous section, the IAM roles used for data access are created and managed by the data management layer. These IAM roles have a trust policy providing federated access to the external IdPs used by the analytics tools of the consumption layer. It implies that for every new analytical service created with a different IDP, the IAM roles used for data access on data domains must be updated to trust this new IdP.

Using NNEDH as an example of a data management solution, the synchronization mechanism is demonstrated in the following figure.

Synchronization mechanism in a data management solution

Taking as an example a scenario where a new analytics service is created, the steps in this workflow are as follows:

  1. A user with access to the administration console of the consumption layer instantiates a new analytics service, such as JupyterHub.
  2. A job running on AWS Fargate creates the resources needed for this new analytics service, such as an Amazon Elastic Compute Cloud (Amazon EC2) instance for JupyterHub, and the IdP required, such as a new SAML IdP.
  3. When the IdP is created in the previous step, an event is added in an Amazon Simple Notification Service (Amazon SNS) topic with its details, such as name and SAML metadata.
  4. In the NNEDH control plane, a Lambda job is triggered by new events on this SNS topic. This job creates the IAM IdP, if needed, and updates the trust policy of the required IAM roles in all the AWS accounts used as data domains, adding the trust on the IdP used by the new analytics service.

In this architecture, all the update steps are event-triggered and scalable. This means that users of new analytics services can access their datasets almost instantaneously when they are created. In the same way, when a service is removed, the federation to the IdP is automatically removed if not used by other services.

Propagate changes on data domains to analytics services

Changes to data domains, such as the creation of a new S3 bucket used as a dataset, or adding or removing data access to a group, must be reflected immediately on analytics services of the consumption layer. To accomplish it, a mechanism is used to synchronize the entitlement database with the relevant changes made in NNEDH. This flow is demonstrated in the following figure.

Changes propagation flow

Taking as an example a scenario where access to a specific dataset is granted to a new group, the steps in this workflow are as follows:

  1. Using the NNEDH admin console, a data owner approves a dataset sharing request that grants access on a dataset to an Active Directory group.
  2. In the AWS account of the related data domain, the dataset components such as the S3 bucket and Lake Formation are updated to provide data access to the new group. The cross-account data sharing in Lake Formation uses AWS RAM.
  3. An event is added in an SNS topic with the current details about this dataset, such as the location of the S3 bucket and the groups that currently have access to it.
  4. In the virtualization layer, the updated information from the data management layer is used to update the entitlement database in DynamoDB.

These steps make sure that changes on data domains are automatically and immediately reflected on the entitlement database, which is used to provide data access to all the analytics services of the consumption layer.

Limitations

Many of these patterns rely on the analytical tool to support a clever use of IAM roles. When this is not the case, the platform teams themselves need to develop custom functionality at the host level to ensure that role accesses are correctly controlled. This, for example, includes writing custom authenticators for JupyterHub.

Conclusion

This post shows an approach to building a scalable and secure data and analytics platform. It showcases some of the mechanisms used at Novo Nordisk and how to strike the right balance between freedom and control. The architecture laid out in the first post in this series enables layer independence, and exposes some extremely useful primitives for data access and governance. We make heavy use of contextual attributes to modulate role permissions at the session level, which provide just-in-time permissions. These permissions are propagated at a scale, across data domains. The upside is that a lot of the complexity related to managing data access permission can be delegated to the relevant business groups, while enabling the end-user consumers of data to think as little as possible about data accesses and focus on providing value for the business use cases. In the case of Novo Nordisk, they can provide better outcomes for patients and acceleration innovation.

The next post in this series describes how end-users can consume data from their analytics tool of choice, aligned with the data access controls detailed in this post.


About the Authors

Jonatan Selsing is former research scientist with a PhD in astrophysics that has turned to the cloud. He is currently the Lead Cloud Engineer at Novo Nordisk, where he enables data and analytics workloads at scale. With an emphasis on reducing the total cost of ownership of cloud-based workloads, while giving full benefit of the advantages of cloud, he designs, builds, and maintains solutions that enable research for future medicines.

Hassen Riahi is a Sr. Data Architect at AWS Professional Services. He holds a PhD in Mathematics & Computer Science on large-scale data management. He works with AWS customers on building data-driven solutions.

Alessandro Fior is a Sr. Data Architect at AWS Professional Services. He is passionate about designing and building modern and scalable data platforms that accelerate companies to extract value from their data.

Moses Arthur comes from a mathematics and computational research background and holds a PhD in Computational Intelligence specialized in Graph Mining. He is currently a Cloud Product Engineer at Novo Nordisk, building GxP-compliant enterprise data lakes and analytics platforms for Novo Nordisk global factories producing digitalized medical products.

Anwar RizalAnwar Rizal is a Senior Machine Learning consultant based in Paris. He works with AWS customers to develop data and AI solutions to sustainably grow their business.

Kumari RamarKumari Ramar is an Agile certified and PMP certified Senior Engagement Manager at AWS Professional Services. She delivers data and AI/ML solutions that speed up cross-system analytics and machine learning models, which enable enterprises to make data-driven decisions and drive new innovations.

Simplify web app authentication: A guide to AD FS federation with Amazon Cognito user pools

Post Syndicated from Leo Drakopoulos original https://aws.amazon.com/blogs/security/simplify-web-app-authentication-a-guide-to-ad-fs-federation-with-amazon-cognito-user-pools/

August 13, 2018: Date this post was first published, on the Front-End Web and Mobile Blog. We updated the CloudFormation template, provided additional clarification on implementation steps, and revised to account for the new Amazon Cognito UI.


User authentication and authorization can be challenging when you’re building web and mobile apps. The challenges include handling user data and passwords, token-based authentication, federating identities from external identity providers (IdPs), managing fine-grained permissions, scalability, and more.

In this blog post, we will show you how to federate identities from Windows Server Active Directory to authenticate users into your web app by using AWS services. The main AWS service that we’ll use for this purpose is Amazon Cognito.

With Amazon Cognito user pools, you can add user sign-up and sign-in to your mobile and web apps by using a secure and scalable user directory. In addition, you can federate users from a SAML IdP with Amazon Cognito user pools, map these users to a user directory, and get standard authentication tokens from a user pool after the user authenticates with a SAML IdP.

This post explains how to integrate Amazon Cognito user pools with Microsoft Active Directory Federation Services (AD FS) to obtain JSON web tokens (JWTs) in your web app—which in turn can be used for downstream authentication. To demonstrate the complete authentication flow, we’ve created a simple REST API that’s built on Amazon API Gateway. The REST API retrieves data from an Amazon DynamoDB table with the help of an AWS Lambda function. We’ll use the JWT tokens that are vended from user pools to authenticate to the REST API, which is hosted on API Gateway.

A benefit of using Amazon Cognito user pools to federate users from a SAML provider is that a user pool supports SAML 2.0 post-binding endpoints. This helps eliminate the need for client-side parsing of the SAML assertion response, and the user pool directly receives the SAML response from your IdP through a user agent.

As part of the SAML federation feature, the user pool acts as a service provider on behalf of your application. The user pool becomes a single point of identity management for your application, and your application doesn’t need to integrate with multiple SAML IdPs.

Solution overview

Figure 1 shows the authentication flow that we present throughout this blog post.

Figure 1: Authentication flow with Amazon Cognito user pool

Figure 1: Authentication flow with Amazon Cognito user pool

As shown in the figure, the authentication flow involves the following steps:

  1. The app starts the sign-up and sign-in process by directing the user to the Cognito user pools hosted web UI. For a mobile app, you can use a web view to show the hosted web UI. For this post, you will use a web app that is hosted on Amazon Simple Storage Service (Amazon S3) fronted by Amazon CloudFront.
  2. The Amazon Cognito user pool determines the appropriate IdP based on your configuration. For AD FS, the IdP is determined by the metadata file or metadata endpoint URL from your SAML IdP. For example, if you use AD FS, the metadata URL looks like the following: https://<yourservername>/FederationMetadata/2007-06/FederationMetadata.xml
  3. The user is redirected to the IdP—in this case, Active Directory.
  4. The IdP authenticates the user if necessary. If the IdP recognizes that the user has an active session, then the IdP skips the authentication to provide a single sign-on experience.
  5. The IdP sends the SAML assertion to Amazon Cognito.
  6. The user’s profile is created in the user pool.
  7. After verifying the SAML assertion and collecting the user attributes (claims) from the assertion, Amazon Cognito returns OIDC tokens (ID, access, and refresh tokens) to the app for the user who is now signed in.
  8. The app then makes a GET request to API Gateway, passing along the JWT token for authorization. If authorized, the request is forwarded to Lambda for data retrieval from DynamoDB.

Installation and configuration walkthrough

To build the authentication flow that we described in the previous section, complete the following steps.

  • Step 1: Install Active Directory and AD FS
  • Step 2: Create an Amazon Cognito user pool
  • Step 3: Configure Active Directory and AD FS
  • Step 4: Complete the Amazon Cognito configuration
  • Step 5: Deploy and configure the web app

Step 1: Install Active Directory and AD FS

You will need to set up Active Directory and AD FS. For instructions on how to install both with an AWS CloudFormation template, see Enabling Federation to AWS Using Windows Active Directory, ADFS, and SAML 2.0. To complete the walkthrough in this blog post, you will need to have a working Active Directory service and AD FS service, and a user created within Active Directory. For this walkthrough, we created a user named bob with an email address of [email protected].

Step 2: Create an Amazon Cognito user pool

  1. Sign in to the Amazon Cognito console and do one of the following:
    • If you have an existing user pool, in the left navigation pane, choose User pools and then choose Create user pool to create a new user pool for this walkthrough.
    • If you don’t have an existing user pool, you will see a landing page. Keep the dropdown list as default and choose Create user pool.
  2. In the Configure sign-in experience section, for Cognito user pool sign-in options, select Email, and then choose Next.
  3. In the Configure security requirements section, under Multi-factor authentication, select No MFA, leave the other fields as default, and then choose Next.
  4. In the Configure sign-up experience section, under Attribute verification and user account confirmation, deselect Allow Cognito to automatically send messages to verify and confirm, and choose Next.
  5. In the Configure message delivery section, under Email, select Send email with Cognito, leave the other fields as default, and then choose Next.
  6. In the Integrate your app section, enter a user pool name, select Use the Cognito Hosted UI, and create a domain name using a Cognito domain.
  7. In the Initial app client section as shown in Figure 2, for App client name, enter SAML-IdP; and for Allowed callback URLs, enter https://localhost. Then choose Next.
    Figure 2: Set up the initial app client to create the Cognito user pool

    Figure 2: Set up the initial app client to create the Cognito user pool

  8. In the Review and create section, review all settings, and then scroll to the bottom of the page and choose Create user pool.

Step 3: Configure Active Directory and AD FS

Now that you’ve created an Amazon Cognito user pool, you need to set up Amazon Cognito as a relying party in the SAML identity provider (in this case, AD FS). After you configure AD FS, you will return to Amazon Cognito to complete the final configurations for the application to work.

  1. Connect to the Windows Server instance where you installed AD FS as an administrator through the remote desktop protocol (RDP).
  2. Open the AD FS 2.0 console.
  3. To make sure that the user you created in Step 1 has an email address, in the user property window for your user, choose General. Figure 3 shows our user named bob in Active Directory with an email address of [email protected].
    Figure 3: User properties of bob in the Active Directory

    Figure 3: User properties of bob in the Active Directory

  4. Determine the Uniform Resource Name (URN) for the Amazon Cognito user pool. The form of the URN is urn:amazon:cognito:sp:<user-pool-id>. You can find the user pool ID in the General settings tab.
  5. Configure AD FS as follows to work with the Amazon Cognito user pool:
    1. Go to Trust Relationships > Relying Party Trusts > Add relying party trusts. This will start a wizard.
    2. Select Enter data about the relying party manually.
    3. Enter a display name for the relying party configuration.
    4. On the next screen, do not configure a certificate.
    5. Enable support for the SAML 2.0 single sign-on service URL.
    6. Add the Amazon Cognito user pool URN as the relying party trust identifier.
    7. Configure the SAML POST binding. The SAML 2.0 post-binding endpoint (also known as the assertion consumer URL) for the Amazon Cognito user pool is https://<domain-prefix>.auth.<<region>.amazoncognito.com/saml2/idpresponse.  You configured this as the domain name in Step 2.6.
    8. Select Permit all users to access this relying party.
    9. Choose Finish.
  6. Navigate to Trust Relationships Relying Party Trusts. You should see that the URN of Amazon Cognito is configured as the relying party, as shown in Figure 4:
Figure 4: Amazon Cognito trusted as the relying party

Figure 4: Amazon Cognito trusted as the relying party

In a SAML federation, the IdP can pass various attributes about the user, the authentication method, or other points of context to the service provider (in this case, Amazon Cognito) in the form of SAML attributes. In AD FS, claim rules are used to assemble these required attributes using a combination of Active Directory lookups, simple transformations, and regular expression-based custom rules. In this example, you will configure two claim rules: Name ID and E-Mail.

  1. The Edit Claim Rules window should already be open. If it isn’t, select your relying party trust from the Trust Relationships > Relying Party Trusts screen, and then, in the Actions tab on the right side, choose Edit Claim Rules.
  2. On the Configure Claim Rule page, enter the following values for each configuration element, and then choose OK.
    • Claim rule name: Name ID
    • Incoming claim type: Windows account name
    • Outgoing claim type: Name ID
    • Outgoing name ID format: Persistent identifier
  3. Repeat the preceding steps for the E-mail claim:
    • Claim rule name: Email
    • Attribute Directory: Active Directory
    • LDAP Attributes: Email Addresses
    • Outgoing Claim Type: Email Address
  4. Before leaving the AD FS configuration, download the metadata file for the AD FS. The metadata URL for AD FS looks like the following: https://<servername>/FederationMetadata/2007-06/FederationMetadata.xmlM. The metadata file describes the endpoint of your SAML IdP (the AD FS service) to the service provider (Amazon Cognito).

Step 4: Complete the Amazon Cognito configuration

  1. Sign in to the Amazon Cognito console.
  2. Select the Amazon Cognito user pool that you created earlier, navigate to Sign-in experience Federated identity provider sign-in, and choose Add identity provider, as shown in Figure 5.
    Figure 5: Add a federated identity provider in the Amazon Cognito console

    Figure 5: Add a federated identity provider in the Amazon Cognito console

  3. Choose SAML as the identity provider.
  4. As shown in Figure 6, enter a name for your identity provider, choose Select file, and then upload the FederationMetadata.xml file that you downloaded at the end of Step 3.
    Figure 6: Set up SAML federation with the user pool

    Figure 6: Set up SAML federation with the user pool

  5. Provide the SAML attribute to map attributes between your SAML provider and your user pool as follows:
    • For User pool attribute, select email.
    • For SAML attribute, enter http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress

    These mappings map the claims from the SAML assertion from AD FS to the user pool attributes. You configured an E-mail claim in AD FS, so you need to map this with the appropriate attribute in the user pool.

  6. Choose Add identity provider.

Step 5: Deploy and configure a web app

To reduce the number of steps required for this walkthrough, we have provided a CloudFormation template that you can use to complete the deployment, which deploys the architecture shown in Figure 7:

Figure 7: Web app architecture deployed by the CloudFormation template

Figure 7: Web app architecture deployed by the CloudFormation template

This architecture is essentially the same as step 8 from the authentication flow diagram (Figure 1) earlier in this post. In Figure 7, we have added Amazon S3 and Amazon CloudFront to the diagram, which is where your static website is hosted. Complete the following steps for this walkthrough:

  • Step 5.1: Create the AWS CloudFormation stack
  • Step 5.2: Manually integrate Amazon Cognito user pools with API Gateway
  • Step 5.3: Update the configuration for Amazon Cognito
  • Step 5.4: Update the configuration for the client-side application and upload to Amazon S3
  • Step 5.5: Insert a row into a DynamoDB table to help you test the application

Step 5.1: Create the AWS CloudFormation stack

Let’s deploy this infrastructure:

  1. Download the code repository, which includes the CloudFormation template named prerequisites.yaml and the sample code for a web app named DataManager.
  2. Navigate to the CloudFormation console in the Region where you deployed the user pool, and choose Create Stack.
  3. To upload the template to Amazon S3, choose Browse and select prerequisites.yaml  in the folder where you downloaded it.
  4. Provide a Stack name and a unique Bucket name.

    Note: S3 bucket names should not contain uppercase characters.

  5. Choose Next, and select I acknowledge that AWS CloudFormation might create IAM resources with custom names.
  6. Choose Create and then wait for the resources to be deployed.

    Note: If the deployment fails with the error message API: s3:CreateBucket Access Denied, review the IAM permissions available for the IAM user or the role used and make sure that the s3:CreateBucket permission has been granted.

Step 5.2: Manually integrate the Amazon Cognito user pool with API Gateway

  1. Open the API Gateway console. You should see that an API named DataManager has been created by CloudFormation, as shown in Figure 8:
    Figure 8: APIs in the API Gateway console

    Figure 8: APIs in the API Gateway console

  2. Under APIs, choose DataManager, and then choose Authorizers.
  3. Choose Create new Authorizer, and then populate the relevant details:
    • For Name, enter SamlAuthorizer (Make sure that the name of the user pool is the same as the one that you created).
    • For Type, select Cognito.
    • For Cognito user pool, enter Samlfederation.
    • For Token source, enter Authorization.

    With this configuration, you use the user pools authorizer to authenticate Get requests to your Rest API that’s hosted on API Gateway. In the dropdown for Cognito User Pool, add the user pool that you created in Step 2: Create an Amazon Cognito user pool. Choose Create.

  4. Navigate back to APIs > Resources, choose GET, and then choose Method Request.
  5. To add the authorizer that you just created, under Settings, in the Authorization dropdown, choose your authorizer. Remember to save the setting by choosing the small tick symbol on the right side. If you don’t see the Cognito authorizer, just wait for several minutes for updates from API Gateway.
    Figure 9: Add the Cognito authorizer for the API GET method

    Figure 9: Add the Cognito authorizer for the API GET method

Step 5.3: Update the configuration for Amazon Cognito

Now you need to update the Amazon Cognito configuration based on the CloudFront distribution that you deployed using the CloudFormation template in Step 5.1.

  1. Navigate to the CloudFormation console and locate the CloudFormation stack that was deployed. As shown in Figure 10, in the Outputs tab, copy the values for CloudfrontEndpoint and DataManagerApiInvokeUrl because you will need them later.
    Figure 10: Outputs of the CloudFormation template deployment

    Figure 10: Outputs of the CloudFormation template deployment

  2. Navigate to the Amazon Cognito console and go to your user pool. Choose the App integration tab, scroll to the bottom of the page, and for App client name, choose the App client that you added during user pool creation.
  3. On the page for your App client, in the Hosted UI section, choose Edit, and then do the following:
    • For both the Allowed callback URLs and Allowed sign-out URLs, enter the CloudFront endpoint.
    • For OAuth grant types, select Implicit grant.
    • For OpenID Connect scopes, select Email and OpenID.
    Figure 11: Configure the hosted UI for the app client

    Figure 11: Configure the hosted UI for the app client

The Amazon Cognito hosted UI provides an OAuth 2.0 compliant authorization server. It includes the default implementation of end user flows, such as registration and authentication. Because the application interacts with Amazon Cognito through an OAuth 2.0 implicit flow, which requires a redirect, the website needs to use HTTPS.

Note: In a production scenario, instead of implicit flow, an authorization code grant is the preferred method in the OAuth 2.0 framework because it’s more secure.

To have an HTTPS endpoint for the Amazon S3 static website, you can use the CloudFront distribution that was deployed by the CloudFormation template in Step 5.1.

When one of your users successfully logs in to the Active Directory infrastructure, the user is automatically redirected to the callback URL. In this case, this is a CloudFront distribution URL with an Amazon Cognito ID token, access token, and refresh token.

Step 5.4: Update the configuration for your client-side application, and upload it to Amazon S3

Navigate to the code that you previously cloned in Step 5.1, and perform the following steps:

  1. With a file manager, navigate to the folder where the cloned content is located. Open the DataManager directory.
  2. Open the js folder. Using a text editor, open the config.js file.
  3. From the Amazon Cognito console, copy the client app application ID as the value of the userPoolClientId property. You can find the application ID in the App clients menu of the Amazon Cognito console.
  4. Change the value of the Region property to the Region that you are using (for example, us-east-2)
  5. While you are still in the Amazon Cognito console, open the Domain name page, and copy the custom prefix into the value for the authDomainPrefix property.
  6. Open the CloudFormation console and choose the stack that was created in Step 5.1. With the stack selected, open the Outputs tab.
    • Copy the value of the CloudfrontEndpoint output variable to the redirect_uri property.
    • Copy the value of the DataManagerApiInvokeUrl output variable to the invokeUri property.
  7. Copy the files to the S3 bucket that hosts the static website. To upload the files, use the AWS Command Line Interface (AWS CLI) or the Amazon S3 console.

Step 5.5: Insert a row into the DynamoDB table to help test your application

The CloudFormation template that you used in Step 5.1 created a DynamoDB table that you can use to test your application. Now you need to add a row to the table (as shown in the Items returned section of Figure 12), so that you can get some results when you test your application. To add a row, in the left menu, choose Tables Update settings to find the table, and then choose Actions Create item.

The Lambda function that retrieves data from the ADFSSecretData DynamoDB table only retrieves data from rows where the email matches the one used to log in to Active Directory. To achieve this, you pass the event.requestContext.authorizer.claims.email.object within the Lambda function. This object contains the email that you used to log in to Active Directory.

Figure 12: Search result of DynamoDB table

Figure 12: Search result of DynamoDB table

Now you’re ready to test the application.

  1. Open the CloudFront URL in your browser and choose Enter. This should immediately take you to the web app landing page. From there, you’re automatically redirected to the Amazon Cognito hosted UI. You should see a screen similar to the following that says Sign in with your corporate ID:
    Figure 13: Cognito hosted UI sign-in page

    Figure 13: Cognito hosted UI sign-in page

  2. After you choose your SAML provider, you are redirected to your AD FS infrastructure that shows a login screen similar to the following:
    Figure 14: AD FS sign-in page

    Figure 14: AD FS sign-in page

    Note: If there’s an error, make sure that there’s a mapping in the host file for your AD FS server, with the appropriate hostname or public IP address of the EC2 instance where the AD FS infrastructure is hosted

    On the login screen, for Username, enter the user’s email address (in our example, that’s Bob’s email address), and for Password, enter the password that you defined in Active Directory, as shown in Figure 14. If the login is successful, you’re redirected back to the web app with a valid ID and access tokens.

    Figure 15: Sample web app home page

    Figure 15: Sample web app home page

  3. Choose Refresh to see the data that you stored in DynamoDB.
    Figure 16: Retrieval of the data from DynamoDB

    Figure 16: Retrieval of the data from DynamoDB

Summary

In this walkthrough, you federated users from AD FS, and successfully authenticated those users to our REST API that’s hosted on API Gateway.

The SAML federation feature in Amazon Cognito helps you set up and integrate your apps with multiple SAML IdPs. By using the SAML federation capabilities of Amazon Cognito, your apps don’t need to handle the type of SAML IdP that they are interacting with. Amazon Cognito takes care of it on behalf of your application.
 


This article was originally written by Adrian Hall, who was an AWS Solutions Architect when he wrote it.
 


 
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Leo Drakopoulos

Leo Drakopoulos

Leo is a Principal Solutions Architect working within the financial services industry. His focus is AWS Serverless and Container-based architectures. He enjoys helping customers adopt a culture of innovation and use cloud-native architectures.

Jun Zhang

Jun Zhang

Jun is a Solutions Architect based in Zurich. He helps Swiss customers architect cloud-based solutions to achieve their business potential. He has a passion for sustainability and strives to solve current environmental challenges with technology. He is also a huge tennis fan and enjoys playing board games a lot.

Content Repository for Unstructured Data with Multilingual Semantic Search: Part 1

Post Syndicated from Patrik Nagel original https://aws.amazon.com/blogs/architecture/content-repository-for-unstructured-data-with-multilingual-semantic-search-part-1/

Unstructured data can make up to 80 percent of data in the day-to-day business of financial organizations. For example, these organizations typically store and read PDFs and images for claim processing, underwriting, and know your customer (KYC). Organizations need to make this ingested data accessible and searchable across different entities while logically separating data access according to role requirements.

In this two-part series, we use AWS services to build an end-to-end content repository for storing and processing unstructured data with the following features:

  • Dynamic access control-based logic over unstructured data
  • Multilingual semantic search capabilities

In part 1, we build the architectural foundation for the content repository, including the resource access control logic and a web UI to upload and list documents.

Solution overview

The content repository includes four building blocks:

Frontend and interaction: For this function, we use AWS Amplify, which is a set of purpose-built tools and features to help frontend web and mobile developers quickly build full-stack applications on AWS. The React application uses the AWS Amplify authentication feature to quickly set up a complete authentication flow integrated into Amazon Cognito. Amplify also hosts the frontend application.

Authentication and authorization: Implementing dynamic resource access control with a combination of roles and attributes is fundamental to your content repository security. Amazon Cognito provides a managed, scalable user directory, user sign-up and sign-in flows, and federation capabilities through third-party identity providers. We use Amazon Cognito user pools as the source of user identity for the content repository. You can work with user pool groups to represent different types of user collection, and you can manage their permissions using a group-associated AWS Identity and Access Management (IAM) role.

Users authenticate against the Amazon Cognito user pool. The web app will exchange the user pool tokens for AWS credentials through an Amazon Cognito identity pool in the content repository. You can complement the IAM role-based authorization model by mapping your relevant attributes to principal tags that will be evaluated as part of IAM permission policies. This allows a dynamic and flexible authorization strategy. For use cases that need federation with third-party identity providers, you can base your user collection on existing user group attributes, such as Active Directory group membership.

Backend and business logic: Authenticated users are redirected to the Amazon API Gateway. API Gateway provides managed publishing for application programming interfaces (APIs) that act as the repository’s “front door.” API Gateway also interacts with the repository’s backend through RESTful APIs. This makes the business logic of the content repository extensible for future use cases, such as transcription and translation. We use AWS Lambda as a serverless, event-driven compute service to run specific business logic code, such as uploading a document to the content repository.

Content storage: Amazon Simple Storage Service (Amazon S3) provides virtually unlimited scalability and high durability. With Amazon S3, you can cost-effectively store unstructured documents in their native formats and make it accessible in a secure and scalable way. Enriching the uploaded documents with tags simplifies data governance with fine-grained access control.

Technical architecture

The technical architecture of the content repository with these four components can be found in Figure 1.

Technical architecture of the content repository

Figure 1. Technical architecture of the content repository

Let’s explore the architecture step by step.

  1. The frontend uses the Amplify JS library to add the authentication UI component to your React app, allowing authenticated users to sign in.
  2. Once the user provides their sign-in credentials, they are redirected to Amazon Cognito user pools to be authenticated.
  3. Once the authentication is successful, Amazon Cognito invokes a pre-token generation Lambda function. This function customizes the identity (ID) token with a new claim called department. This new claim is the Amazon Cognito group name from the cognito:preferred_role claim.
  4. Amazon Cognito returns the identity, access, and refresh token in JSON format to the frontend.
  5. The Amplify client library stores the tokens and handles refreshes using the refresh token while the React frontend application calls the API Gateway with the ID token. Note: Usually, you would use the access token to grant access to authorized resources. For this architecture, we use the ID token because we have enriched it with the custom claim during step 3.
  6. API Gateway uses its native integration with Amazon Cognito and validates the ID token’s signature and expiration using Amazon Cognito user pool authorizer. For more complex authorization scenarios, you can use API Gateway Lambda authorizer with the AWS JSON Web Token (JWT) Verify library for verifying JWTs signed by Amazon Cognito.
  7. After successful validation, API Gateway passes the ID token to the backend Lambda function, which can verify and authorize upon it for access control.
  8. Upon document upload action, the backend Lambda function calls the Amazon Cognito identity pool to exchange the ID token for the temporary AWS credentials associated with the cognito:preferred_role claim.
  9. The document upload Lambda function returns a pre-signed URL with the custom department claim in the Amazon S3 path prefix as well as the object tag. The Amazon S3 pre-signed URL is used for the document upload from the frontend application directly to Amazon S3.
  10. Upon document list action, similar to step 8, the backend Lambda function exchanges the ID token for the temporary AWS credentials. The Lambda function returns only the documents based on the user’s preferred group and associated custom department claim.

Prerequisites

You must have the following prerequisites for this solution:

Walkthrough

Setup

The following steps will deploy two AWS CDK stacks into your AWS account:

  • content-repo-stack (blog-content-repo-stack.ts) creates the environment detailed in Figure 1.
  • demo-data-stack (userpool-demo-data-stack.ts) deploys sample users, groups, and role mappings.

To continue setup, use the following commands:

  1. Clone the project git repository:
    git clone https://github.com/aws-samples/content-repository-with-dynamic-access-control content-repository
  2. Install the necessary dependencies:
    cd content-repository/backend-cdk
    npm install
    
  3. Configure environment variables:
    export CDK_DEFAULT_ACCOUNT=$(aws sts get-caller-identity --query 'Account' --output text)
    export CDK_DEFAULT_REGION=$(aws configure get region)
    
  4. Bootstrap your account for AWS CDK usage:
    cdk bootstrap aws://$CDK_DEFAULT_ACCOUNT/$CDK_DEFAULT_REGION
  5. Deploy the code to your AWS account:
    cdk deploy --all

Using the repository

Once you deploy the CDK stacks in your AWS account, follow these steps:

1. Access the frontend application:

a. Copy the amplifyHostedAppUrl value shown in the AWS CDK output from the content-repo-stack.

b. Use the URL with your web browser to access the frontend application.

c. A temporary page displays until the automated build and deployment of the React application completes after 4-5 minutes.

2. Application sign-in and role-based access control (RBAC):

a. The React webpage prompts you to sign in and then change the temporary password.

b. The content repository provides two demo users with credentials as part of the demo-data-stack in the AWS CDK output. In this walkthrough, we use the sales-user user, which belongs to the sales department group to validate RBAC.

3. Upload a document to the content repository:

a. Authenticate as sales-user.

b. Select upload to upload your first document to the content repository.

c. The repository provides sample documents in the assets sub-folder.

4. List your uploaded document:

a. Select list to show the uploaded sales content.

b. To verify the dynamic access control, repeat steps 2 and 3 for the marketing-user user, which belongs to the marketing department group.

c. Sign-in to the AWS Management Console and navigate to the Amazon S3 bucket with the prefix content-repo-stack-s3sourcebucket to confirm that all the uploaded content exists.

Implementation notes

Frontend deployment and cross-origin access

The content-repo-stack contains an AwsCustomResource construct. This construct uses the Amplify API to start the release job of the Amplify hosted frontend application. The preBuild step of the Amplify application build specification dynamically configures its backend for the Amazon Cognito-based authentication. The required Amazon Cognito configuration parameters are retrieved from the AWS Systems Manager Parameter Store during build time. Similarly, the Amplify application postBuild step updates the Amazon S3 cross-origin resource sharing (CORS) rule for the Amazon S3 bucket to only allow cross-origin access from the Amplify-hosted URL of the frontend application.

Application sign-in and access control

The Amazon Cognito identity pool configuration is set to Choose role from token for authenticated users, as in Figure 2. This setup permits authenticated users to pass the roles in the ID token that the Amazon Cognito user pool assigned. Backend Lambda functions use the roles that appear in the cognito:roles and cognito:preferred_role claims in the ID token for RBAC.

Amazon Cognito identity pool configuration – using tokens to assign roles to authenticated users

Figure 2. Amazon Cognito identity pool configuration – using tokens to assign roles to authenticated users

In the attributes for access control section, we configured a custom mapping from the augmented department token claim to a tag key, as in Figure 3. The backend logic uses the tag key to match the PrincipalTag condition in IAM policies to control access to AWS resources.

Amazon Cognito identity pool configuration – custom mapping from claim names to tag keys

Figure 3. Amazon Cognito identity pool configuration – custom mapping from claim names to tag keys

Document upload

The presigned_url.py Lambda function generates a pre-signed Amazon S3 URL using the department token claim as the key. This function automatically organizes the uploaded document into a logical structure in the Amazon S3 source bucket. Accordingly, the cognito:preferred_role used for the Amazon S3 client credentials in the Lambda function has a permission policy using the PrincipalTag department to dynamically limit access to the Amazon S3 key, as in Figure 4.

Permission policy using PrincipalTag to upload documents to Amazon S3

Figure 4. Permission policy using PrincipalTag to upload documents to Amazon S3

Document listing

The list functionality only shows the uploaded content belonging to the preferred group of authenticated Amazon Cognito user pool user. To only list the files that a specific user (for example, sales-user) has access to, use the PrincipalTag s3:prefix condition, as in Figure 5.

Permission policy using s3:prefix condition with session tags to list documents

Figure 5. Permission policy using s3:prefix condition with session tags to list documents

Cleanup

In the backend-cdk subdirectory, delete the deployed resources:

cdk destroy --all

Conclusion

In this blog, we demonstrated how to build a content repository with an easy-to-use web application for unstructured data that ingests documents while maintaining dynamic access control for users within departments. These steps provide a foundation to build your own content repository to store and process documents. As next steps, based on your organization’s security requirements, you can implement more complex access control use cases by balancing IAM role and principal tags. For example, you can use Amazon Cognito user pool custom attributes for additional dimensions such as document “clearance” with optional modification in the pre-token generation Lambda.

In the next part of this blog series, we will enrich the content repository with multi-lingual semantic search features while maintaining the access control fundamentals we’ve already implemented. For additional information on how you can build a solution to search for information across multiple scanned documents, PDFs, and images with compliance capabilities, please refer our Document Understanding Solution from AWS Solutions Library.

Securing Lambda Function URLs using Amazon Cognito, Amazon CloudFront and AWS WAF

Post Syndicated from Marcia Villalba original https://aws.amazon.com/blogs/compute/securing-lambda-function-urls-using-amazon-cognito-amazon-cloudfront-and-aws-waf/

This post is written by Madhu Singh (Solutions Architect), and Krupanidhi Jay (Solutions Architect).

Lambda function URLs is a dedicated HTTPs endpoint for a AWS Lambda function. You can configure a function URL to have two methods of authentication: IAM and NONE. IAM authentication means that you are restricting access to the function URL (and in-turn access to invoke the Lambda function) to certain AWS principals (such as roles or users). Authentication type of NONE means that the Lambda function URL has no authentication and is open for anyone to invoke the function.

This blog shows how to use Lambda function URLs with an authentication type of NONE and use custom authorization logic as part of the function code, and to only allow requests that present valid Amazon Cognito credentials when invoking the function. You also learn ways to protect Lambda function URL against common security threats like DDoS using AWS WAF and Amazon CloudFront.

Lambda function URLs provides a simpler way to invoke your function using HTTP calls. However, it is not a replacement for Amazon API Gateway, which provides advanced features like request validation and rate throttling.

Solution overview

There are four core components in the example.

1. A Lambda function with function URLs enabled

At the core of the example is a Lambda function with the function URLs feature enabled with the authentication type of NONE. This function responds with a success message if a valid authorization code is passed during invocation. If not, it responds with a failure message.

2. Amazon Cognito User Pool

Amazon Cognito user pools enable user authentication on websites and mobile apps. You can also enable publicly accessible Login and Sign-Up pages in your applications using Amazon Cognito user pools’ feature called the hosted UI.

In this example, you use a user pool and the associated Hosted UI to enable user login and sign-up on the website used as entry point. This Lambda function validates the authorization code against this Amazon Cognito user pool.

3. CloudFront distribution using AWS WAF

CloudFront is a content delivery network (CDN) service that helps deliver content to end users with low latency, while also improving the security posture for your applications.

AWS WAF is a web application firewall that helps protect your web applications or APIs against common web exploits and bots and AWS Shield is a managed distributed denial of service (DDoS) protection service that safeguards applications running on AWS. AWS WAF inspects the incoming request according to the configured Web Access Control List (web ACL) rules.

Adding CloudFront in front of your Lambda function URL helps to cache content closer to the viewer, and activating AWS WAF and AWS Shield helps in increasing security posture against multiple types of attacks, including network and application layer DDoS attacks.

4. Public website that invokes the Lambda function

The example also creates a public website built on React JS and hosted in AWS Amplify as the entry point for the demo. This website works both in authenticated mode and in guest mode. For authentication, the website uses Amazon Cognito user pools hosted UI.

Solution architecture

This shows the architecture of the example and the information flow for user requests.

In the request flow:

  1. The entry point is the website hosted in AWS Amplify. In the home page, when you choose “sign in”, you are redirected to the Amazon Cognito hosted UI for the user pool.
  2. Upon successful login, Amazon Cognito returns the authorization code, which is stored as a cookie with the name “code”. The user is redirected back to the website, which has an “execute Lambda” button.
  3. When the user choose “execute Lambda”, the value from the “code” cookie is passed in the request body to the CloudFront distribution endpoint.
  4. The AWS WAF web ACL rules are configured to determine whether the request is originating from the US or Canada IP addresses and to determine if the request should be allowed to invoke Lambda function URL origin.
  5. Allowed requests are forwarded to the CloudFront distribution endpoint.
  6. CloudFront is configured to allow CORS headers and has the origin set to the Lambda function URL. The request that CloudFront receives is passed to the function URL.
  7. This invokes the Lambda function associated with the function URL, which validates the token.
  8. The function code does the following in order:
    1. Exchange the authorization code in the request body (passed as the event object to Lambda function) to access_token using Amazon Cognito’s token endpoint (check the documentation for more details).
      1. Amazon Cognito user pool’s attributes like user pool URL, Client ID and Secret are retrieved from AWS Systems Manager Parameter Store (SSM Parameters).
      2. These values are stored in SSM Parameter Store at the time these resources are deployed via AWS CDK (see “how to deploy” section)
    2. The access token is then verified to determine its authenticity.
    3. If valid, the Lambda function returns a message stating user is authenticated as <username> and execution was successful.
    4. If either the authorization code was not present, for example, the user was in “guest mode” on the website, or the code is invalid or expired, the Lambda function returns a message stating that the user is not authorized to execute the function.
  9. The webpage displays the Lambda function return message as an alert.

Getting started

Pre-requisites:

Before deploying the solution, please follow the README from the GitHub repository and take the necessary steps to fulfill the pre-requisites.

Deploy the sample solution

1. From the code directory, download the dependencies:

$ npm install

2. Start the deployment of the AWS resources required for the solution:

$ cdk deploy

Note:

  • optionally pass in the –profile argument if needed
  • The deployment can take up to 15 minutes

3. Once the deployment completes, the output looks similar to this:

Open the amplifyAppUrl from the output in your browser. This is the URL for the demo website. If you don’t see the “Welcome to Compute Blog” page, the Amplify app is still building, and the website is not available yet. Retry in a few minutes. This website works either in an authenticated or unauthenticated state.

Test the authenticated flow

  1. To test the authenticated flow, choose “Sign In”.

2. In the sign-in page, choose on sign-up (for the first time) and create a user name and password.

3. To use an existing an user name and password, enter those credentials and choose login.

4. Upon successful sign-in or sign up, you are redirected back to the webpage with “Execute Lambda” button.

5. Choose this button. In a few seconds, an alert pop-up shows the logged in user and that the Lambda execution is successful.

Testing the unauthenticated flow

1. To test the unauthenticated flow, from the Home page, choose “Continue”.

2. Choose “Execute Lambda” and in a few seconds, you see a message that you are not authorized to execute the Lambda function.

Testing the geo-block feature of AWS WAF

1. Access the website from a Region other than US or Canada. If you are physically in the US or Canada, you may use a VPN service to connect to a Region other than US or Canada.

2. Choose the “Execute Lambda” button. In the Network trace of browser, you can see the call to invoke Lambda function was blocked with Forbidden response.

3. To try either the authenticated or unauthenticated flow again, choose “Return to Home Page” to go back to the home page with “Sign In” and “Continue” buttons.

Cleaning up

To delete the resources provisioned, run the cdk destroy command from the AWS CDK CLI.

Conclusion

In this blog, you create a Lambda function with function URLs enabled with NONE as the authentication type. You then implemented a custom authentication mechanism as part of your Lambda function code. You also increased the security of your Lambda function URL by setting it as Origin for the CloudFront distribution and using AWS WAF Geo and IP limiting rules for protection against common web threats, like DDoS.

For more serverless learning resources, visit Serverless Land.

Lifting and shifting a web application to AWS Serverless: Part 2

Post Syndicated from Marcia Villalba original https://aws.amazon.com/blogs/compute/lifting-and-shifting-a-web-application-to-aws-serverless-part-2/

In part 1, you learn if it is possible to migrate a non-serverless web application to a serverless environment without changing much code. You learn different tools that can help you in this process, like Lambda Web Adaptor and AWS Amplify. By the end, you have migrated an application into a serverless environment.

However, if you test the migrated app, you find two issues. The first one is that the user session is not sticky. Every time you log in, you are logged out unexpectedly from the application. The second one is that when you create a new product, you cannot upload new images of that product.

This final post analyzes each of the problems in detail and shows solutions. In addition, it analyzes the cost and performance of the solution.

Authentication and authorization migration

The original application handled the authentication and authorization by itself. There is a user directory in the database, with the passwords and emails for each of the users. There are APIs and middleware that take care of validating that the user is logged in before showing the application. All the logic for this is developed inside the Node.js/Express application.

However, with the current migrated application every time you log in, you are logged out unexpectedly from the application. This is because the server code is responsible for handling the authentication and the authorization of the users, and now our server is running in an AWS Lambda function and functions are stateless. This means that there will be one function running per request—a request can load all the products in the landing page, get the details for a product, or log in to the site—and if you do something in one of these functions, the state is not shared across.

To solve this, you must remove the authentication and authorization mechanisms from the function and use a service that can preserve the state across multiple invocations of the functions.

There are many ways to solve this challenge. You can add a layer of authentication and session management with a database like Redis, or build a new microservice that is in charge of authentication and authorization that can handle the state, or use an existing managed service for this.

Because of the migration requirements, we want to keep the cost as low as possible, with the fewest changes to the application. The better solution is to use an existing managed service to handle authentication and authorization.

This demo uses Amazon Cognito, which provides user authentication and authorization to AWS resources in a managed, pay as you go way. One rapid approach is to replace all the server code with calls to Amazon Cognito using the AWS SDK. But this adds complexity that can be replaced completely by just invoking Amazon Cognito APIs from the React application.

Using Cognito

For example, when a new user is registered, the application creates the user in the Amazon Cognito user pool directory, as well as in the application database. But when a user logs in to the web app, the application calls Amazon Cognito API directly from the AWS Amplify application. This way minimizes the amount of code needed.

In the original application, all authenticated server APIs are secured with a middleware that validates that the user is authenticated by providing an access token. With the new setup that doesn’t change, but the token is generated by Amazon Cognito and then it can be validated in the backend.

let auth = (req, res, next) => {
    const token = req.headers.authorization;
    const jwtToken = token.replace('Bearer ', '');

    verifyToken(jwtToken)
        .then((valid) => {
            if (valid) {
                getCognitoUser(jwtToken).then((email) => {
                    User.findByEmail(email, (err, user) => {
                        if (err) throw err;
                        if (!user)
                            return res.json({
                                isAuth: false,
                                error: true,
                            });

                        req.user = user;
                        next();
                    });
                });
            } else {
                throw Error('Not valid Token');
            }
        })
        .catch((error) => {
            return res.json({
                isAuth: false,
                error: true,
            });
        });
};

You can see how this is implemented step by step in this video.

Storage migration

In the original application, when a new product is created, a new image is uploaded to the Node.js/Express server. However, now the application resides in a Lambda function. The code (and files) that are part of that function cannot change, unless the function is redeployed. Consequently, you must separate the user storage from the server code.

For doing this, there are a couple of solutions: using Amazon Elastic File System (EFS) or Amazon S3. EFS is a file storage, and you can use that to have a dynamic storage where you upload the new images. Using EFS won’t change much of the code, as the original implementation is using a directory inside the server as EFS provides. However, using EFS adds more complexity to the application, as functions that use EFS must be inside an Amazon Virtual Private Cloud (Amazon VPC).

Using S3 to upload your images to the application is simpler, as it only requires that an S3 bucket exists. For doing this, you must refactor the application, from uploading the image to the application API to use the AWS Amplify library that uploads and gets images from S3.

export function uploadImage(file) {
    const fileName = `uploads/${file.name}`;

    const request = Storage.put(fileName, file).then((result) => {
        return {
            image: fileName,
            success: true,
        };
    });

    return {
        type: IMAGE_UPLOAD,
        payload: request,
    };
}

An important benefit of using S3 is that you can also use Amazon CloudFront to accelerate the retrieval of the images from the cloud. In this way, you can speed up the loading time of your page. You can see how this is implemented step by step in this video.

How much does this application cost?

If you deploy this application in an empty AWS account, most of the usage of this application is covered by the AWS Free Tier. Serverless services, like Lambda and Amazon Cognito, have a forever free tier that gives you the benefits in pricing for the lifetime of hosting the application.

  • AWS Lambda—With 100 requests per hour, an average 10ms invocation and 1GB of memory configured, it costs 0 USD per month.
  • Amazon S3—Using S3 standard, hosting 1 GB per month and 10k PUT and GET requests per month costs 0.07 USD per month. This can be optimized using S3 Intelligent-Tiering.
  • Amazon Cognito—Provides 50,000 monthly active users for free.
  • AWS Amplify—If you build your client application once a week, serve 3 GB and store 1 GB per month, this costs 0.87 USD.
  • AWS Secrets Manager—There are two secrets stored using Secrets Manager and this costs 1.16 USD per month. This can be optimized by using AWS System Manager Parameter Store and AWS Key Management Service (AWS KMS).
  • MongoDB Atlas Forever free shared cluster.

The total monthly cost of this application is approximately 2.11 USD.

Performance analysis

After you migrate the application, you can run a page speed insight tool, to measure this application’s performance. This tool provides results mostly about the front end and the experience that the user perceives. The results are displayed in the following image. The performance of this website is good, according to the insight tool performance score – it responds quickly and the user experience is good.

Page speed insight tool results

After the application is migrated to a serverless environment, you can do some refactoring to improve further the overall performance. One alternative is whenever a new image is uploaded, it gets resized and formatted into the correct next-gen format automatically using the event driven capabilities that S3 provides. Another alternative is to use Lambda on Edge to serve the right image size for the device, as it is possible to format the images on the fly when serving them from a distribution.

You can run load tests for understanding how your backend and database will perform. For this, you can use Artillery, an open-source library that allows you to run load tests. You can run tests with the expected maximum load your site will get and ensure that your site can handle it.

For example, you can configure a test that sends 30 requests per seconds to see how your application reacts:

config:
  target: 'https://xxx.lambda-url.eu-west-1.on.aws'
  phases:
    - duration: 240
      arrivalRate: 30
      name: Testing
scenarios:
  - name: 'Test main page'
    flow:
      - post:
          url: '/api/product/getProducts/'

This test is performed on the backend APIs, not only testing your backend but also your integration with the MongoDB. After running it, you can see how the Lambda function performs on the Amazon CloudWatch dashboard.

Running this load test helps you understand the limitations of your system. For example, if you run a test with too many concurrent users, you might see that the number of throttles in your function increases. This means that you need to lift the limit of invocations of the functions you can have at the same time.

Or when increasing the requests per second, you may find that the MongoDB cluster starts throttling your requests. This is because you are using the free tier and that has a set number of connections. You might need a larger cluster or to migrate your database to another service that provides a large free tier, like Amazon DynamoDB.

Cloudwatch dashboard

Conclusion

In this two-part article, you learn if it is possible to migrate a non-serverless web application to a serverless environment without changing much code. You learn different tools that can help you in this process, like AWS Lambda Web Adaptor and AWS Amplify, and how to solve some of the typical challenges that we have, like storage and authentication.

After the application is hosted in a fully serverless environment, it can scale up and down to meet your needs. This web application is also performant once the backend is hosted in a Lambda function.

If you need, from here you can start using the strangler pattern to refactor the application to take advantage of the benefits of event-driven architecture.

To see all the steps of the migration, there is a playlist that contains all the tutorials for you to follow.

For more serverless learning resources, visit Serverless Land.