Tag Archives: Amazon Cognito

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.

Want more AWS Security how-to content, news, and feature announcements? Follow us on Twitter.

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.

Want more AWS Security news? Follow us on Twitter.

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.

Want more AWS Security how-to content, news, and feature announcements? Follow us on Twitter.

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.

Want more AWS Security news? Follow us on Twitter.

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.

Have a question? Contact us for general support services.

Want more AWS Security news? Follow us on Twitter.

Author photo

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.
 


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

Want more AWS Security news? Follow us on Twitter.

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.

Lifting and shifting a web application to AWS Serverless: Part 1

Post Syndicated from Marcia Villalba original https://aws.amazon.com/blogs/compute/lifting-and-shifting-a-web-application-to-aws-serverless-part-1/

Customers migrating to the cloud often want to get the benefits of serverless architecture. But what is the best approach and is it possible? There are many strategies to do a migration, but lift and shift is often the fastest way to get to production with the migrated workload.

You might also wonder if it’s possible to lift and shift an existing application that runs in a traditional environment to serverless. This blog post shows how to do this for a Mongo, Express, React, and Node.js (MERN) stack web app. However, the discussions presented in this post apply to other stacks too.

Why do a lift and shift migration?

Lift and shift, or sometimes referred to as rehosting the application, is moving the application with as few changes as possible. Lift and shift migrations often allow you to get the new workload in production as fast as possible. When migrating to serverless, lift and shift can bring a workload that is not yet in the cloud or in a serverless environment to use managed and serverless services quickly.

Migrating a non-serverless workload to serverless with lift and shift might not bring all the serverless benefits right away, but it enables the development team to refactor, using the strangler pattern, the parts of the application that might benefit from what serverless technologies offer.

Why migrate a web app to serverless?

Web apps hosted in a serverless environment benefit most from the capability of serverless applications to scale automatically and for paying for what you use.

Imagine that you have a personal web app with little traffic. If you are hosting in a serverless environment, you don’t pay a fixed price to have the servers up and running. Your web app has only a few requests and the rest of the time is idle.

This benefit applies to the opposite case. For an owner of a small ecommerce site running on a server, imagine if a social media influencer with millions of followers recommends one of their products. Suddenly, thousands of requests arrive and make the site unavailable. If the site is hosted on a serverless platform, the application will scale to the traffic that it receives.

Requirements for migration

Before starting a migration, it is important to define the nonfunctional requirements that you need the new application to have. These requirements help when you must make architectural decisions during the migration process.

These are the nonfunctional requirements of this migration:

  • Environment that scales to zero and scales up automatically.
  • Pay as little as possible for idle time.
  • Configure as little infrastructure as possible.
  • Automatic high availability of the application.
  • Minimal changes to the original code.

Application overview

This blog post guides you on how to migrate a MERN application. The original application is hosted in two different servers: One contains the Mongo database and another contains the Node/js/Express and ReactJS applications.

Application overview

This demo application simulates a swag ecommerce site. The database layer stores the products, users, and the purchases history. The server layer takes care of the ecommerce business logic, hosting the product images, and user authentication and authorization. The web layer takes care of all the user interaction and communicates with the server layer using REST APIs.

How the application looks like

These are the changes that you must make to migrate to a serverless environment:

  • Database migration: Migrate the database from on-premises to MongoDB Atlas.
  • Backend migration: Migrate the NodeJS/Express application from on-premises to an AWS Lambda function.
  • Web app migration: Migrate the React web app from on-premises to AWS Amplify.
  • Authentication migration: Migrate the custom-built authentication to use Amazon Cognito.
  • Storage migration: Migrate the local storage of images to use Amazon S3 and Amazon CloudFront.

The following image shows the proposed solution for the migrated application:

Proposed architecture

Database migration

The database is already in a MongoDB vanilla container that has all the data for this application. As MongoDB is the database engine for our stack, their recommended solution to migrate to serverless is to use MongoDB Atlas. Atlas provides a database cluster in the cloud that scales automatically and you pay for what you use.

To get started, create a new Atlas cluster, then migrate the data from the existing database to the serverless one. To migrate the data, you can first dump all the content of the database to a dump folder and then restore it to the cloud:

mongodump --uri="mongodb://<localuser>:<localpassword>@localhost:27017"

mongorestore --uri="mongodb+srv://<user>:<password>@<clustername>.debkm.mongodb.net" .

After doing that, your data is now in the cloud. The next step is to change the configuration string in the server to point to the new database. To see this in action, check this video that shows a walkthrough of the migration.

Backend migration

Migrating the Node.js/Express backend is the most challenging of the layers to migrate to a serverless environment, as the server layer is a Node.js application that runs in a server.

One option for this migration is to use AWS Fargate. Fargate is a serverless container service that allows you to scale automatically and you pay as you go. Another option is to use AWS AppRunner, a container service that auto scales and you also pay as you go. However, neither of these options align with our migration requirements, as they don’t scale to zero.

Another option for the lift and shift migration of this Node.js application is to use Lambda with the AWS Lambda Web Adapter. The AWS Lambda Web Adapter is an open-source project that allows you to build web applications with familiar frameworks, like Express.js, Flask, SpringBoot, and run it on Lambda. You can learn more about this project in its GitHub repository.

Lambda Web Adapter

Using this project, you can create a new Lambda function that has the Express/NodeJS application as the function code. You can lift and shift all the code into the function. If you want a step-by-step tutorial on how to do this, check out this video.

const lambdaAdapterFunction = new Function(this,`${props.stage}-LambdaAdapterFunction`,
            {
                runtime: Runtime.NODEJS_16_X,
                code: Code.fromAsset('backend-app'),
                handler: 'run.sh',
                environment: {
                    AWS_LAMBDA_EXEC_WRAPPER: '/opt/bootstrap',
                    REGION: this.region,
                    ASYNC_INIT: 'true',
                },
                memorySize: 1024,
                layers: [layerLambdaAdapter],
                timeout: Duration.seconds(2),
                tracing: Tracing.ACTIVE,
            }
        );

The next step is to create an HTTP endpoint for the server application. There are three options for doing this: API Gateway, Application Load Balancer (ALB) , or to use Lambda Function URLs. All the options are compatible with Lambda Web Adapter and can solve the challenge for you.

For this demo, choose function URLs, as they are simple to configure and one function URL forwards all routes to the Express server. API Gateway and ALB require more configuration and have separate costs, while the cost of function URLs is included in the Lambda function.

Web app migration

The final layer to migrate is the React application. The best way to migrate the web layer and to adhere to the migration requirements is to use AWS Amplify to host it. AWS Amplify is a fully managed service that provides many features like hosting web applications and managing the CICD process for the web app. It provides client libraries to connect to different AWS resources, and many other features.

Migrating the React application is as simple as creating a new Amplify application in your AWS account and uploading the React application to a code repository like GitHub. This AWS Amplify application is connected to a GitHub branch, and when there is a new commit in this branch, AWS Amplify redeploys the code.

The Amplify application receives configuration parameters like the function URL endpoint (the server URL) using environmental variables.

const amplifyApp = new App(this, `${props.stage}-AmplifyReactShopApp`, {
            sourceCodeProvider: new GitHubSourceCodeProvider({
                owner: config.frontend.owner,
                repository: config.frontend.repository_name,
                oauthToken: SecretValue.secretsManager('github-token'),
            }),
            environmentVariables: {
                REGION: this.region,
                SERVER_URL: props.serverURL,
            },
        });

If you want to see a step-by-step guide on how to make your web layer serverless, you can check this video.

Next steps

However, if you test this migrated app, you will 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.

In part two, I analyze each of the problems in detail and find solutions. These issues arise because of the stateless and immutable characteristics of this solution. The next part of this article explains how to solve these issues, also it analyzes costs and performance of the solution.

Conclusion

In this 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 the AWS Lambda Web Adaptor and AWS Amplify.

If you want to see the migration in action and learn all the steps for this, there is a playlist that contains all the tutorials for you to follow and learn how this is possible.

For more serverless learning resources, visit Serverless Land.

Web application access control patterns using AWS services

Post Syndicated from Zili Gao original https://aws.amazon.com/blogs/architecture/web-application-access-control-patterns-using-aws-services/

The web application client-server pattern is widely adopted. The access control allows only authorized clients to access the backend server resources by authenticating the client and providing granular-level access based on who the client is.

This post focuses on three solution architecture patterns that prevent unauthorized clients from gaining access to web application backend servers. There are multiple AWS services applied in these architecture patterns that meet the requirements of different use cases.

OAuth 2.0 authentication code flow

Figure 1 demonstrates the fundamentals to all the architectural patterns discussed in this post. The blog Understanding Amazon Cognito user pool OAuth 2.0 grants describes the details of different OAuth 2.0 grants, which can vary the flow to some extent.

A typical OAuth 2.0 authentication code flow

Figure 1. A typical OAuth 2.0 authentication code flow

The architecture patterns detailed in this post use Amazon Cognito as the authorization server, and Amazon Elastic Compute Cloud instance(s) as resource server. The client can be any front-end application, such as a mobile application, that sends a request to the resource server to access the protected resources.

Pattern 1

Figure 2 is an architecture pattern that offloads the work of authenticating clients to Application Load Balancer (ALB).

Application Load Balancer integration with Amazon Cognito

Figure 2. Application Load Balancer integration with Amazon Cognito

ALB can be used to authenticate clients through the user pool of Amazon Cognito:

  1. The client sends HTTP request to ALB endpoint without authentication-session cookies.
  2. ALB redirects the request to Amazon Cognito authentication endpoint. The client is authenticated by Amazon Cognito.
  3. The client is directed back to the ALB with the authentication code.
  4. The ALB uses the authentication code to obtain the access token from the Amazon Cognito token endpoint and also uses the access token to get client’s user claims from Amazon Cognito UserInfo endpoint.
  5. The ALB prepares the authentication session cookie containing encrypted data and redirects client’s request with the session cookie. The client uses the session cookie for all further requests. The ALB validates the session cookie and decides if the request can be passed through to its targets.
  6. The validated request is forwarded to the backend instances with the ALB adding HTTP headers that contain the data from the access token and user-claims information.
  7. The backend server can use the information in the ALB added headers for granular-level permission control.

The key takeaway of this pattern is that the ALB maintains the whole authentication context by triggering client authentication with Amazon Cognito and prepares the authentication-session cookie for the client. The Amazon Cognito sign-in callback URL points to the ALB, which allows the ALB access to the authentication code.

More details about this pattern can be found in the documentation Authenticate users using an Application Load Balancer.

Pattern 2

The pattern demonstrated in Figure 3 offloads the work of authenticating clients to Amazon API Gateway.

Amazon API Gateway integration with Amazon Cognito

Figure 3. Amazon API Gateway integration with Amazon Cognito

API Gateway can support both REST and HTTP API. API Gateway has integration with Amazon Cognito, whereas it can also have control access to HTTP APIs with a JSON Web Token (JWT) authorizer, which interacts with Amazon Cognito. The ALB can be integrated with API Gateway. The client is responsible for authenticating with Amazon Cognito to obtain the access token.

  1. The client starts authentication with Amazon Cognito to obtain the access token.
  2. The client sends REST API or HTTP API request with a header that contains the access token.
  3. The API Gateway is configured to have:
    • Amazon Cognito user pool as the authorizer to validate the access token in REST API request, or
    • A JWT authorizer, which interacts with the Amazon Cognito user pool to validate the access token in HTTP API request.
  4. After the access token is validated, the REST or HTTP API request is forwarded to the ALB, and:
    • The API Gateway can route HTTP API to private ALB via a VPC endpoint.
    • If a public ALB is used, the API Gateway can route both REST API and HTTP API to the ALB.
  5. API Gateway cannot directly route REST API to a private ALB. It can route to a private Network Load Balancer (NLB) via a VPC endpoint. The private ALB can be configured as the NLB’s target.

The key takeaways of this pattern are:

  • API Gateway has built-in features to integrate Amazon Cognito user pool to authorize REST and/or HTTP API request.
  • An ALB can be configured to only accept the HTTP API requests from the VPC endpoint set by API Gateway.

Pattern 3

Amazon CloudFront is able to trigger AWS Lambda functions deployed at AWS edge locations. This pattern (Figure 4) utilizes a feature of Lambda@Edge, where it can act as an authorizer to validate the client requests that use an access token, which is usually included in HTTP Authorization header.

Using Amazon CloudFront and AWS Lambda@Edge with Amazon Cognito

Figure 4. Using Amazon CloudFront and AWS Lambda@Edge with Amazon Cognito

The client can have an individual authentication flow with Amazon Cognito to obtain the access token before sending the HTTP request.

  1. The client starts authentication with Amazon Cognito to obtain the access token.
  2. The client sends a HTTP request with Authorization header, which contains the access token, to the CloudFront distribution URL.
  3. The CloudFront viewer request event triggers the launch of the function at Lambda@Edge.
  4. The Lambda function extracts the access token from the Authorization header, and validates the access token with Amazon Cognito. If the access token is not valid, the request is denied.
  5. If the access token is validated, the request is authorized and forwarded by CloudFront to the ALB. CloudFront is configured to add a custom header with a value that can only be shared with the ALB.
  6. The ALB sets a listener rule to check if the incoming request has the custom header with the shared value. This makes sure the internet-facing ALB only accepts requests that are forwarded by CloudFront.
  7. To enhance the security, the shared value of the custom header can be stored in AWS Secrets Manager. Secrets Manager can trigger an associated Lambda function to rotate the secret value periodically.
  8. The Lambda function also updates CloudFront for the added custom header and ALB for the shared value in the listener rule.

The key takeaways of this pattern are:

  • By default, CloudFront will remove the authorization header before forwarding the HTTP request to its origin. CloudFront needs to be configured to forward the Authorization header to the origin of the ALB. The backend server uses the access token to apply granular levels of resource access permission.
  • The use of Lambda@Edge requires the function to sit in us-east-1 region.
  • The CloudFront-added custom header’s value is kept as a secret that can only be shared with the ALB.

Conclusion

The architectural patterns discussed in this post are token-based web access control methods that are fully supported by AWS services. The approach offloads the OAuth 2.0 authentication flow from the backend server to AWS services. The services managed by AWS can provide the resilience, scalability, and automated operability for applying access control to a web application.

Top 2021 AWS service launches security professionals should review – Part 2

Post Syndicated from Marta Taggart original https://aws.amazon.com/blogs/security/top-2021-aws-service-launches-security-professionals-should-review-part-2/

In Part 1 of this two-part series, we shared an overview of some of the most important 2021 Amazon Web Services (AWS) Security service and feature launches. In this follow-up, we’ll dive deep into additional launches that are important for security professionals to be aware of and understand across all AWS services. There have already been plenty in the first half of 2022, so we’ll highlight those soon, as well.

AWS Identity

You can use AWS Identity Services to build Zero Trust architectures, help secure your environments with a robust data perimeter, and work toward the security best practice of granting least privilege. In 2021, AWS expanded the identity source options, AWS Region availability, and support for AWS services. There is also added visibility and power in the permission management system. New features offer new integrations, additional policy checks, and secure resource sharing across AWS accounts.

AWS Single Sign-On

For identity management, AWS Single Sign-On (AWS SSO) is where you create, or connect, your workforce identities in AWS once and manage access centrally across your AWS accounts in AWS Organizations. In 2021, AWS SSO announced new integrations for JumpCloud and CyberArk users. This adds to the list of providers that you can use to connect your users and groups, which also includes Microsoft Active Directory Domain Services, Okta Universal Directory, Azure AD, OneLogin, and Ping Identity.

AWS SSO expanded its availability to new Regions: AWS GovCloud (US), Europe (Paris), and South America (São Paulo) Regions. Another very cool AWS SSO development is its integration with AWS Systems Manager Fleet Manager. This integration enables you to log in interactively to your Windows servers running on Amazon Elastic Compute Cloud (Amazon EC2) while using your existing corporate identities—try it, it’s fantastic!

AWS Identity and Access Management

For access management, there have been a range of feature launches with AWS Identity and Access Management (IAM) that have added up to more power and visibility in the permissions management system. Here are some key examples.

IAM made it simpler to relate a user’s IAM role activity to their corporate identity. By setting the new source identity attribute, which persists through role assumption chains and gets logged in AWS CloudTrail, you can find out who is responsible for actions that IAM roles performed.

IAM added support for policy conditions, to help manage permissions for AWS services that access your resources. This important feature launch of service principal conditions helps you to distinguish between API calls being made on your behalf by a service principal, and those being made by a principal inside your account. You can choose to allow or deny the calls depending on your needs. As a security professional, you might find this especially useful in conjunction with the aws:CalledVia condition key, which allows you to scope permissions down to specify that this account principal can only call this API if they are calling it using a particular AWS service that’s acting on their behalf. For example, your account principal can’t generally access a particular Amazon Simple Storage Service (Amazon S3) bucket, but if they are accessing it by using Amazon Athena, they can do so. These conditions can also be used in service control policies (SCPs) to give account principals broader scope across an account, organizational unit, or organization; they need not be added to individual principal policies or resource policies.

Another very handy new IAM feature launch is additional information about the reason for an access denied error message. With this additional information, you can now see which of the relevant access control policies (for example, IAM, resource, SCP, or VPC endpoint) was the cause of the denial. As of now, this new IAM feature is supported by more than 50% of all AWS services in the AWS SDK and AWS Command Line Interface, and a fast-growing number in the AWS Management Console. We will continue to add support for this capability across services, as well as add more features that are designed to make the journey to least privilege simpler.

IAM Access Analyzer

AWS Identity and Access Management (IAM) Access Analyzer provides actionable recommendations to set secure and functional permissions. Access Analyzer introduced the ability to preview the impact of policy changes before deployment and added over 100 policy checks for correctness. Both of these enhancements are integrated into the console and are also available through APIs. Access Analyzer also provides findings for external access allowed by resource policies for many services, including a previous launch in which IAM Access Analyzer was directly integrated into the Amazon S3 management console.

IAM Access Analyzer also launched the ability to generate fine-grained policies based on analyzing past AWS CloudTrail activity. This feature provides a great new capability for DevOps teams or central security teams to scope down policies to just the permissions needed, making it simpler to implement least privilege permissions. IAM Access Analyzer launched further enhancements to expand policy checks, and the ability to generate a sample least-privilege policy from past activity was expanded beyond the account level to include an analysis of principal behavior within the entire organization by analyzing log activity stored in AWS CloudTrail.

AWS Resource Access Manager

AWS Resource Access Manager (AWS RAM) helps you securely share your resources across unrelated AWS accounts within your organization or organizational units (OUs) in AWS Organizations. Now you can also share your resources with IAM roles and IAM users for supported resource types. This update enables more granular access using managed permissions that you can use to define access to shared resources. In addition to the default managed permission defined for each shareable resource type, you now have more flexibility to choose which permissions to grant to whom for resource types that support additional managed permissions. Additionally, AWS RAM added support for global resource types, enabling you to provision a global resource once, and share that resource across your accounts. A global resource is one that can be used in multiple AWS Regions; the first example of a global resource is found in AWS Cloud WAN, currently in preview as of this publication. AWS RAM helps you more securely share an AWS Cloud WAN core network, which is a managed network containing AWS and on-premises networks. With AWS RAM global resource sharing, you can use the Cloud WAN core network to centrally operate a unified global network across Regions and accounts.

AWS Directory Service

AWS Directory Service for Microsoft Active Directory, also known as AWS Managed Microsoft Active Directory (AD), was updated to automatically provide domain controller and directory utilization metrics in Amazon CloudWatch for new and existing directories. Analyzing these utilization metrics helps you quantify your average and peak load times to identify the need for additional domain controllers. With this, you can define the number of domain controllers to meet your performance, resilience, and cost requirements.

Amazon Cognito

Amazon Cognito identity pools (federated identities) was updated to enable you to use attributes from social and corporate identity providers to make access control decisions and simplify permissions management in AWS resources. In Amazon Cognito, you can choose predefined attribute-tag mappings, or you can create custom mappings using the attributes from social and corporate providers’ access and ID tokens, or SAML assertions. You can then reference the tags in an IAM permissions policy to implement attribute-based access control (ABAC) and manage access to your AWS resources. Amazon Cognito also launched a new console experience for user pools and now supports targeted sign out through refresh token revocation.

Governance, control, and logging services

There were a number of important releases in 2021 in the areas of governance, control, and logging services.

AWS Organizations

AWS Organizations added a number of important import features and integrations during 2021. Security-relevant services like Amazon Detective, Amazon Inspector, and Amazon Virtual Private Cloud (Amazon VPC) IP Address Manager (IPAM), as well as others like Amazon DevOps Guru, launched integrations with Organizations. Others like AWS SSO and AWS License Manager upgraded their Organizations support by adding support for a Delegated Administrator account, reducing the need to use the management account for operational tasks. Amazon EC2 and EC2 Image Builder took advantage of the account grouping capabilities provided by Organizations to allow cross-account sharing of Amazon Machine Images (AMIs) (for more details, see the Amazon EC2 section later in this post). Organizations also got an updated console, increased quotas for tag policies, and provided support for the launch of an API that allows for programmatic creation and maintenance of AWS account alternate contacts, including the very important security contact (although that feature doesn’t require Organizations). For more information on the value of using the security contact for your accounts, see the blog post Update the alternate security contact across your AWS accounts for timely security notifications.

AWS Control Tower

2021 was also a good year for AWS Control Tower, beginning with an important launch of the ability to take over governance of existing OUs and accounts, as well as bulk update of new settings and guardrails with a single button click or API call. Toward the end of 2021, AWS Control Tower added another valuable enhancement that allows it to work with a broader set of customers and use cases, namely support for nested OUs within an organization.

AWS CloudFormation Guard 2.0

Another important milestone in 2021 for creating and maintaining a well-governed cloud environment was the re-launch of CloudFormation Guard as Cfn-Guard 2.0. This launch was a major overhaul of the Cfn-Guard domain-specific language (DSL), a DSL designed to provide the ability to test infrastructure-as-code (IaC) templates such as CloudFormation and Terraform to make sure that they conform with a set of constraints written in the DSL by a central team, such as a security organization or network management team.

This approach provides a powerful new middle ground between the older security models of prevention (which provide developers only an access denied message, and often can’t distinguish between an acceptable and an unacceptable use of the same API) and a detect and react model (when undesired states have already gone live). The Cfn-Guard 2.0 model gives builders the freedom to build with IaC, while allowing central teams to have the ability to reject infrastructure configurations or changes that don’t conform to central policies—and to do so with completely custom error messages that invite dialog between the builder team and the central team, in case the rule is unnuanced and needs to be refined, or if a specific exception needs to be created.

For example, a builder team might be allowed to provision and attach an internet gateway to a VPC, but the team can do this only if the routes to the internet gateway are limited to a certain pre-defined set of CIDR ranges, such as the public addresses of the organization’s branch offices. It’s not possible to write an IAM policy that takes into account the CIDR values of a VPC route table update, but you can write a Cfn-Guard 2.0 rule that allows the creation and use of an internet gateway, but only with a defined and limited set of IP addresses.

AWS Systems Manager Incident Manager

An important launch that security professionals should know about is AWS Systems Manager Incident Manager. Incident Manager provides a number of powerful capabilities for managing incidents of any kind, including operational and availability issues but also security issues. With Incident Manager, you can automatically take action when a critical issue is detected by an Amazon CloudWatch alarm or Amazon EventBridge event. Incident Manager runs pre-configured response plans to engage responders by using SMS and phone calls, can enable chat commands and notifications using AWS Chatbot, and runs automation workflows with AWS Systems Manager Automation runbooks. The Incident Manager console integrates with AWS Systems Manager OpsCenter to help you track incidents and post-incident action items from a central place that also synchronizes with third-party management tools such as Jira Service Desk and ServiceNow. Incident Manager enables cross-account sharing of incidents using AWS RAM, and provides cross-Region replication of incidents to achieve higher availability.

AWS CloudTrail

AWS CloudTrail added some great new logging capabilities in 2021, including logging data-plane events for Amazon DynamoDB and Amazon Elastic Block Store (Amazon EBS) direct APIs (direct APIs allow access to EBS snapshot content through a REST API). CloudTrail also got further enhancements to its machine-learning based CloudTrail Insights feature, including a new one called ErrorRate Insights.

Amazon S3

Amazon Simple Storage Service (Amazon S3) is one of the most important services at AWS, and its steady addition of security-related enhancements is always big news. Here are the 2021 highlights.

Access Points aliases

Amazon S3 introduced a new feature, Amazon S3 Access Points aliases. With Amazon S3 Access Points aliases, you can make the access points backwards-compatible with a large amount of existing code that is programmed to interact with S3 buckets rather than access points.

To understand the importance of this launch, we have to go back to 2019 to the launch of Amazon S3 Access Points. Access points are a powerful mechanism for managing S3 bucket access. They provide a great simplification for managing and controlling access to shared datasets in S3 buckets. You can create up to 1,000 access points per Region within each of your AWS accounts. Although bucket access policies remain fully enforced, you can delegate access control from the bucket to its access points, allowing for distributed and granular control. Each access point enforces a customizable policy that can be managed by a particular workgroup, while also avoiding the problem of bucket policies needing to grow beyond their maximum size. Finally, you can also bind an access point to a particular VPC for its lifetime, to prevent access directly from the internet.

With the 2021 launch of Access Points aliases, Amazon S3 now generates a unique DNS name, or alias, for each access point. The Access Points aliases look and acts just like an S3 bucket to existing code. This means that you don’t need to make changes to older code to use Amazon S3 Access Points; just substitute an Access Points aliases wherever you previously used a bucket name. As a security team, it’s important to know that this flexible and powerful administrative feature is backwards-compatible and can be treated as a drop-in replacement in your various code bases that use Amazon S3 but haven’t been updated to use access point APIs. In addition, using Access Points aliases adds a number of powerful security-related controls, such as permanent binding of S3 access to a particular VPC.

Bucket Keys

Amazon S3 launched support for S3 Inventory and S3 Batch Operations to identify and copy objects to use S3 Bucket Keys, which can help reduce the costs of server-side encryption (SSE) with AWS Key Management Service (AWS KMS).

S3 Bucket Keys were launched at the end of 2020, another great launch that security professionals should know about, so here is an overview in case you missed it. S3 Bucket Keys are data keys generated by AWS KMS to provide another layer of envelope encryption in which the outer layer (the S3 Bucket Key) is cached by S3 for a short period of time. This extra key layer increases performance and reduces the cost of requests to AWS KMS. It achieves this by decreasing the request traffic from Amazon S3 to AWS KMS from a one-to-one model—one request to AWS KMS for each object written to or read from Amazon S3—to a one-to-many model using the cached S3 Bucket Key. The S3 Bucket Key is never stored persistently in an unencrypted state outside AWS KMS, and so Amazon S3 ultimately must always return to AWS KMS to encrypt and decrypt the S3 Bucket Key, and thus, the data. As a result, you still retain control of the key hierarchy and resulting encrypted data through AWS KMS, and are still able to audit Amazon S3 returning periodically to AWS KMS to refresh the S3 Bucket Keys, as logged in CloudTrail.

Returning to our review of 2021, S3 Bucket Keys gained the ability to use Amazon S3 Inventory and Amazon S3 Batch Operations automatically to migrate objects from the higher cost, slightly lower-performance SSE-KMS model to the lower-cost, higher-performance S3 Bucket Keys model.

Simplified ownership and access management

The final item from 2021 for Amazon S3 is probably the most important of all. Last year was the year that Amazon S3 achieved fully modernized object ownership and access management capabilities. You can now disable access control lists to simplify ownership and access management for data in Amazon S3.

To understand this launch, we need to go in time to the origins of Amazon S3, which is one of the oldest services in AWS, created even before IAM was launched in 2011. In those pre-IAM days, a storage system like Amazon S3 needed to have some kind of access control model, so Amazon S3 invented its own: Amazon S3 access control lists (ACLs). Using ACLs, you could add access permissions down to the object level, but only with regard to access by other AWS account principals (the only kind of identity that was available at the time), or public access (read-only or read-write) to an object. And in this model, objects were always owned by the creator of the object, not the bucket owner.

After IAM was introduced, Amazon S3 added the bucket policy feature, a type of resource policy that provides the rich features of IAM, including full support for all IAM principals (users and roles), time-of-day conditions, source IP conditions, ability to require encryption, and more. For many years, Amazon S3 access decisions have been made by combining IAM policy permissions and ACL permissions, which has served customers well. But the object-writer-is-owner issue has often caused friction. The good news for security professionals has been that a deny by either type of access control type overrides an allow by the other, so there were no security issues with this bi-modal approach. The challenge was that it could be administratively difficult to manage both resource policies—which exist at the bucket and access point level—and ownership and ACLs—which exist at the object level. Ownership and ACLs might potentially impact the behavior of only a handful of objects, in a bucket full of millions or billions of objects.

With the features released in 2021, Amazon S3 has removed these points of friction, and now provides the features needed to reduce ownership issues and to make IAM-based policies the only access control system for a specified bucket. The first step came in 2020 with the ability to make object ownership track bucket ownership, regardless of writer. But that feature applied only to newly-written objects. The final step is the 2021 launch we’re highlighting here: the ability to disable at the bucket level the evaluation of all existing ACLs—including ownership and permissions—effectively nullifying all object ACLs. From this point forward, you have the mechanisms you need to govern Amazon S3 access with a combination of S3 bucket policies, S3 access point policies, and (within the same account) IAM principal policies, without worrying about legacy models of ACLs and per-object ownership.

Additional database and storage service features

AWS Backup Vault Lock

AWS Backup added an important new additional layer for backup protection with the availability of AWS Backup Vault Lock. A vault lock feature in AWS is the ability to configure a storage policy such that even the most powerful AWS principals (such as an account or Org root principal) can only delete data if the deletion conforms to the preset data retention policy. Even if the credentials of a powerful administrator are compromised, the data stored in the vault remains safe. Vault lock features are extremely valuable in guarding against a wide range of security and resiliency risks (including accidental deletion), notably in an era when ransomware represents a rising threat to data.

Prior to AWS Backup Vault Lock, AWS provided the extremely useful Amazon S3 and Amazon S3 Glacier vault locking features, but these previous vaulting features applied only to the two Amazon S3 storage classes. AWS Backup, on the other hand, supports a wide range of storage types and databases across the AWS portfolio, including Amazon EBS, Amazon Relational Database Service (Amazon RDS) including Amazon Aurora, Amazon DynamoDB, Amazon Neptune, Amazon DocumentDB, Amazon Elastic File System (Amazon EFS), Amazon FSx for Lustre, Amazon FSx for Windows File Server, Amazon EC2, and AWS Storage Gateway. While built on top of Amazon S3, AWS Backup even supports backup of data stored in Amazon S3. Thus, this new AWS Backup Vault Lock feature effectively serves as a vault lock for all the data from most of the critical storage and database technologies made available by AWS.

Finally, as a bonus, AWS Backup added two more features in 2021 that should delight security and compliance professionals: AWS Backup Audit Manager and compliance reporting.

Amazon DynamoDB

Amazon DynamoDB added a long-awaited feature: data-plane operations integration with AWS CloudTrail. DynamoDB has long supported the recording of management operations in CloudTrail—including a long list of operations like CreateTable, UpdateTable, DeleteTable, ListTables, CreateBackup, and many others. What has been added now is the ability to log the potentially far higher volume of data operations such as PutItem, BatchWriteItem, GetItem, BatchGetItem, and DeleteItem. With this launch, full database auditing became possible. In addition, DynamoDB added more granular control of logging through DynamoDB Streams filters. This feature allows users to vary the recording in CloudTrail of both control plane and data plane operations, at the table or stream level.

Amazon EBS snapshots

Let’s turn now to a simple but extremely useful feature launch affecting Amazon Elastic Block Store (Amazon EBS) snapshots. In the past, it was possible to accidently delete an EBS snapshot, which is a problem for security professionals because data availability is a part of the core security triad of confidentiality, integrity, and availability. Now you can manage that risk and recover from accidental deletions of your snapshots by using Recycle Bin. You simply define a retention policy that applies to all deleted snapshots, and then you can define other more granular policies, for example using longer retention periods based on snapshot tag values, such as stage=prod. Along with this launch, the Amazon EBS team announced EBS Snapshots Archive, a major price reduction for long-term storage of snapshots.

AWS Certificate Manager Private Certificate Authority

2021 was a big year for AWS Certificate Manager (ACM) Private Certificate Authority (CA) with the following updates and new features:

Network and application protection

We saw a lot of enhancements in network and application protection in 2021 that will help you to enforce fine-grained security policies at important network control points across your organization. The services and new capabilities offer flexible solutions for inspecting and filtering traffic to help prevent unauthorized resource access.

AWS WAF

AWS WAF launched AWS WAF Bot Control, which gives you visibility and control over common and pervasive bots that consume excess resources, skew metrics, cause downtime, or perform other undesired activities. The Bot Control managed rule group helps you monitor, block, or rate-limit pervasive bots, such as scrapers, scanners, and crawlers. You can also allow common bots that you consider acceptable, such as status monitors and search engines. AWS WAF also added support for custom responses, managed rule group versioning, in-line regular expressions, and Captcha. The Captcha feature has been popular with customers, removing another small example of “undifferentiated work” for customers.

AWS Shield Advanced

AWS Shield Advanced now automatically protects web applications by blocking application layer (L7) DDoS events with no manual intervention needed by you or the AWS Shield Response Team (SRT). When you protect your resources with AWS Shield Advanced and enable automatic application layer DDoS mitigation, Shield Advanced identifies patterns associated with L7 DDoS events and isolates this anomalous traffic by automatically creating AWS WAF rules in your web access control lists (ACLs).

Amazon CloudFront

In other edge networking news, Amazon CloudFront added support for response headers policies. This means that you can now add cross-origin resource sharing (CORS), security, and custom headers to HTTP responses returned by your CloudFront distributions. You no longer need to configure your origins or use custom Lambda@Edge or CloudFront Functions to insert these headers.

CloudFront Functions were another great 2021 addition to edge computing, providing a simple, inexpensive, and yet highly secure method for running customer-defined code as part of any CloudFront-managed web request. CloudFront functions allow for the creation of very efficient, fine-grained network access filters, such the ability to block or allow web requests at a region or city level.

Amazon Virtual Private Cloud and Route 53

Amazon Virtual Private Cloud (Amazon VPC) added more-specific routing (routing subnet-to-subnet traffic through a virtual networking device) that allows for packet interception and inspection between subnets in a VPC. This is particularly useful for highly-available, highly-scalable network virtual function services based on Gateway Load Balancer, including both AWS services like AWS Network Firewall, as well as third-party networking services such as the recently announced integration between AWS Firewall Manager and Palo Alto Networks Cloud Next Generation Firewall, powered by Gateway Load Balancer.

Another important set of enhancements to the core VPC experience came in the area of VPC Flow Logs. Amazon VPC launched out-of-the-box integration with Amazon Athena. This means with a few clicks, you can now use Athena to query your VPC flow logs delivered to Amazon S3. Additionally, Amazon VPC launched three associated new log features that make querying more efficient by supporting Apache Parquet, Hive-compatible prefixes, and hourly partitioned files.

Following Route 53 Resolver’s much-anticipated launch of DNS logging in 2020, the big news for 2021 was the launch of its DNS Firewall capability. Route 53 Resolver DNS Firewall lets you create “blocklists” for domains you don’t want your VPC resources to communicate with, or you can take a stricter, “walled-garden” approach by creating “allowlists” that permit outbound DNS queries only to domains that you specify. You can also create alerts for when outbound DNS queries match certain firewall rules, allowing you to test your rules before deploying for production traffic. Route 53 Resolver DNS Firewall launched with two managed domain lists—malware domains and botnet command and control domains—enabling you to get started quickly with managed protections against common threats. It also integrated with Firewall Manager (see the following section) for easier centralized administration.

AWS Network Firewall and Firewall Manager

Speaking of AWS Network Firewall and Firewall Manager, 2021 was a big year for both. Network Firewall added support for AWS Managed Rules, which are groups of rules based on threat intelligence data, to enable you to stay up to date on the latest security threats without writing and maintaining your own rules. AWS Network Firewall features a flexible rules engine enabling you to define firewall rules that give you fine-grained control over network traffic. As of the launch in late 2021, you can enable managed domain list rules to block HTTP and HTTPS traffic to domains identified as low-reputation, or that are known or suspected to be associated with malware or botnets. Prior to that, another important launch was new configuration options for rule ordering and default drop, making it simpler to write and process rules to monitor your VPC traffic. Also in 2021, Network Firewall announced a major regional expansion following its initial launch in 2020, and a range of compliance achievements and eligibility including HIPAA, PCI DSS, SOC, and ISO.

Firewall Manager also had a strong 2021, adding a number of additional features beyond its initial core area of managing network firewalls and VPC security groups that provide centralized, policy-based control over many other important network security capabilities: Amazon Route 53 Resolver DNS Firewall configurations, deployment of the new AWS WAF Bot Control, monitoring of VPC routes for AWS Network Firewall, AWS WAF log filtering, AWS WAF rate-based rules, and centralized logging of AWS Network Firewall logs.

Elastic Load Balancing

Elastic Load Balancing now supports forwarding traffic directly from Network Load Balancer (NLB) to Application Load Balancer (ALB). With this important new integration, you can take advantage of many critical NLB features such as support for AWS PrivateLink and exposing static IP addresses for applications that still require ALB.

In addition, Network Load Balancer now supports version 1.3 of the TLS protocol. This adds to the existing TLS 1.3 support in Amazon CloudFront, launched in 2020. AWS plans to add TLS 1.3 support for additional services.

The AWS Networking team also made Amazon VPC private NAT gateways available in both AWS GovCloud (US) Regions. The expansion into the AWS GovCloud (US) Regions enables US government agencies and contractors to move more sensitive workloads into the cloud by helping them to address certain regulatory and compliance requirements.

Compute

Security professionals should also be aware of some interesting enhancements in AWS compute services that can help improve their organization’s experience in building and operating a secure environment.

Amazon Elastic Compute Cloud (Amazon EC2) launched the Global View on the console to provide visibility to all your resources across Regions. Global View helps you monitor resource counts, notice abnormalities sooner, and find stray resources. A few days into 2022, another simple but extremely useful EC2 launch was the new ability to obtain instance tags from the Instance Metadata Service (IMDS). Many customers run code on Amazon EC2 that needs to introspect about the EC2 tags associated with the instance and then change its behavior depending on the content of the tags. Prior to this launch, you had to associate an EC2 role and call the EC2 API to get this information. That required access to API endpoints, either through a NAT gateway or a VPC endpoint for Amazon EC2. Now, that information can be obtained directly from the IMDS, greatly simplifying a common use case.

Amazon EC2 launched sharing of Amazon Machine Images (AMIs) with AWS Organizations and Organizational Units (OUs). Previously, you could share AMIs only with specific AWS account IDs. To share AMIs within AWS Organizations, you had to explicitly manage sharing of AMIs on an account-by-account basis, as they were added to or removed from AWS Organizations. With this new feature, you no longer have to update your AMI permissions because of organizational changes. AMI sharing is automatically synchronized when organizational changes occur. This feature greatly helps both security professionals and governance teams to centrally manage and govern AMIs as you grow and scale your AWS accounts. As previously noted, this feature was also added to EC2 Image Builder. Finally, Amazon Data Lifecycle Manager, the tool that manages all your EBS volumes and AMIs in a policy-driven way, now supports automatic deprecation of AMIs. As a security professional, you will find this helpful as you can set a timeline on your AMIs so that, if the AMIs haven’t been updated for a specified period of time, they will no longer be considered valid or usable by development teams.

Looking ahead

In 2022, AWS continues to deliver experiences that meet administrators where they govern, developers where they code, and applications where they run. We will continue to summarize important launches in future blog posts. If you’re interested in learning more about AWS services, join us for AWS re:Inforce, the AWS conference focused on cloud security, identity, privacy, and compliance. AWS re:Inforce 2022 will take place July 26–27 in Boston, MA. Registration is now open. Register now with discount code SALxUsxEFCw to get $150 off your full conference pass to AWS re:Inforce. For a limited time only and while supplies last. We look forward to seeing you there!

To stay up to date on the latest product and feature launches and security use cases, be sure to read the What’s New with AWS announcements (or subscribe to the RSS feed) and the AWS Security Blog.

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

Want more AWS Security news? Follow us on Twitter.

Author

Marta Taggart

Marta is a Seattle-native and Senior Product Marketing Manager in AWS Security Product Marketing, where she focuses on data protection services. Outside of work you’ll find her trying to convince Jack, her rescue dog, not to chase squirrels and crows (with limited success).

Mark Ryland

Mark Ryland

Mark is the director of the Office of the CISO for AWS. He has over 30 years of experience in the technology industry and has served in leadership roles in cybersecurity, software engineering, distributed systems, technology standardization and public policy. Previously, he served as the Director of Solution Architecture and Professional Services for the AWS World Public Sector team.

Use Amazon Cognito to add claims to an identity token for fine-grained authorization

Post Syndicated from Ajit Ambike original https://aws.amazon.com/blogs/security/use-amazon-cognito-to-add-claims-to-an-identity-token-for-fine-grained-authorization/

With Amazon Cognito, you can quickly add user sign-up, sign-in, and access control to your web and mobile applications. After a user signs in successfully, Cognito generates an identity token for user authorization. The service provides a pre token generation trigger, which you can use to customize identity token claims before token generation. In this blog post, we’ll demonstrate how to perform fine-grained authorization, which provides additional details about an authenticated user by using claims that are added to the identity token. The solution uses a pre token generation trigger to add these claims to the identity token.

Scenario

Imagine a web application that is used by a construction company, where engineers log in to review information related to multiple projects. We’ll look at two different ways of designing the architecture for this scenario: a standard design and a more optimized design.

Standard architecture

A sample standard architecture for such an application is shown in Figure 1, with labels for the various workflow steps:

  1. The user interface is implemented by using ReactJS (a JavaScript library for building user interfaces).
  2. The user pool is configured in Amazon Cognito.
  3. The back end is implemented by using Amazon API Gateway.
  4. AWS Lambda functions exist to implement business logic.
  5. The AWS Lambda CheckUserAccess function (5) checks whether the user has authorization to call the AWS Lambda functions (4).
  6. The project information is stored in an Amazon DynamoDB database.
Figure 1: Lambda functions that need the user’s projectID call the GetProjectID Lambda function

Figure 1: Lambda functions that need the user’s projectID call the GetProjectID Lambda function

In this scenario, because the user has access to information from several projects, several backend functions use calls to the CheckUserAccess Lambda function (step 5 in Figure 1) in order to serve the information that was requested. This will result in multiple calls to the function for the same user, which introduces latency into the system.

Optimized architecture

This blog post introduces a new optimized design, shown in Figure 2, which substantially reduces calls to the CheckUserAccess API endpoint:

  1. The user logs in.
  2. Amazon Cognito makes a single call to the PretokenGenerationLambdaFunction-pretokenCognito function.
  3. The PretokenGenerationLambdaFunction-pretokenCognito function queries the Project ID from the DynamoDB table and adds that information to the Identity token.
  4. DynamoDB delivers the query result to the PretokenGenerationLambdaFunction-pretokenCognito function.
  5. This Identity token is passed in the authorization header for making calls to the Amazon API Gateway endpoint.
  6. Information in the identity token claims is used by the Lambda functions that contain business logic, for additional fine-grained authorization. Therefore, the CheckUserAccess function (7) need not be called.

The improved architecture is shown in Figure 2.

Figure 2. Get the projectID and inset it in a custom claim in the Identity token

Figure 2. Get the projectID and inset it in a custom claim in the Identity token

The benefits of this approach are:

  1. The number of calls to get the Project ID from the DynamoDB table are reduced, which in turn reduces overall latency.
  2. The dependency on the CheckUserAccess Lambda function is removed from the business logic. This reduces coupling in the architecture, as depicted in the diagram.

In the code sample provided in this post, the user interface is run locally from the user’s computer, for simplicity.

Code sample

You can download a zip file that contains the code and the AWS CloudFormation template to implement this solution. The code that we provide to illustrate this solution is described in the following sections.

Prerequisites

Before you deploy this solution, you must first do the following:

  1. Download and install Python 3.7 or later.
  2. Download the AWS SDK for Python (Boto3) library by using the following pip command.
    pip install boto3
  3. Install the argparse package by using the following pip command.
    pip install argparse
  4. Install the AWS Command Line Interface (AWS CLI).
  5. Configure the AWS CLI.
  6. Download a code editor for Python. We used Visual Studio Code for this post.
  7. Install Node.js.

Description of infrastructure

The code provided with this post installs the following infrastructure in your AWS account.

Resource Description
Amazon Cognito user pool The users, added by the addUserInfo.py script, are added to this pool. The client ID is used to identify the web client that will connect to the user pool. The user pool domain is used by the web client to request authentication of the user.
Required AWS Identity and Access Management (IAM) roles and policies Policies used for running the Lambda function and connecting to the DynamoDB database.
Lambda function for the pre token generation trigger A Lambda function to add custom claims to the Identity token.
DynamoDB table with user information A sample database to store user information that is specific to the application.

Deploy the solution

In this section, we describe how to deploy the infrastructure, save the trigger configuration, add users to the Cognito user pool, and run the web application.

To deploy the solution infrastructure

  1. Download the zip file to your machine. The readme.md file in the addclaimstoidtoken folder includes a table that describes the key files in the code.
  2. Change the directory to addclaimstoidtoken.
    cd addclaimstoidtoken
  3. Review stackInputs.json. Change the value of the userPoolDomainName parameter to a random unique value of your choice. This example uses pretokendomainname as the Amazon Cognito domain name; you should change it to a unique domain name of your choice.
  4. Deploy the infrastructure by running the following Python script.
    python3 setup_pretoken.py

    After the CloudFormation stack creation is complete, you should see the details of the infrastructure created as depicted in Figure 3.

    Figure 3: Details of infrastructure

    Figure 3: Details of infrastructure

Now you’re ready to add users to your Amazon Cognito user pool.

To add users to your Cognito user pool

  1. To add users to the Cognito user pool and configure the DynamoDB store, run the Python script from the addclaimstoidtoken directory.
    python3 add_user_info.py
  2. This script adds one user. It will prompt you to provide a username, email, and password for the user.

    Note: Because this is sample code, advanced features of Cognito, like multi-factor authentication, are not enabled. We recommend enabling these features for a production application.

    The addUserInfo.py script performs two actions:

    • Adds the user to the Cognito user pool.
      Figure 4: User added to the Cognito user pool

      Figure 4: User added to the Cognito user pool

    • Adds sample data to the DynamoDB table.
      Figure 5: Sample data added to the DynamoDB table named UserInfoTable

      Figure 5: Sample data added to the DynamoDB table named UserInfoTable

Now you’re ready to run the application to verify the custom claim addition.

To run the web application

  1. Change the directory to the pre-token-web-app directory and run the following command.
    cd pre-token-web-app
  2. This directory contains a ReactJS web application that displays details of the identity token. On the terminal, run the following commands to run the ReactJS application.
    npm install
    npm start

    This should open http://localhost:8081 in your default browser window that shows the Login button.

    Figure 6: Browser opens to URL http://localhost:8081

    Figure 6: Browser opens to URL http://localhost:8081

  3. Choose the Login button. After you do so, the Cognito-hosted login screen is displayed. Log in to the website with the user identity you created by using the addUserInfo.py script in step 1 of the To add users to your Cognito user pool procedure.
    Figure 7: Input credentials in the Cognito-hosted login screen

    Figure 7: Input credentials in the Cognito-hosted login screen

  4. When the login is successful, the next screen displays the identity and access tokens in the URL. You can reveal the token details to verify that the custom claim has been added to the token by choosing the Show Token Detail button.
    Figure 8: Token details displayed in the browser

    Figure 8: Token details displayed in the browser

What happened behind the scenes?

In this web application, the following steps happened behind the scenes:

  1. When you ran the npm start command on the terminal command line, that ran the react-scripts start command from package.json. The port number (8081) was configured in the pre-token-web-app/.env file. This opened the web application that was defined in app.js in the default browser at the URL http://localhost:8081.
  2. The Login button is configured to navigate to the URL that was defined in the constants.js file. The constants.js file was generated during the running of the setup_pretoken.py script. This URL points to the Cognito-hosted default login user interface.
  3. When you provided the login information (username and password), Amazon Cognito authenticated the user. Before generating the set of tokens (identity token and access token), Cognito first called the pre-token-generation Lambda trigger. This Lambda function has the code to connect to the DynamoDB database. The Lambda function can then access the project information for the user that is stored in the userInfo table. The Lambda function read this project information and added it to the identity token that was delivered to the web application.

    Lambda function code

    const AWS = require("aws-sdk");
    
    // Create the DynamoDB service object
    var ddb = new AWS.DynamoDB({ apiVersion: "2012-08-10" });
    
    // PretokenGeneration Lambda
    exports.handler = async function (event, context) {
        var eventUserName = "";
        var projects = "";
    
        if (!event.userName) {
            return event;
        }
    
        var params = {
            ExpressionAttributeValues: {
                ":v1": {
                    S: event.userName
                }
            },
            KeyConditionExpression: "userName = :v1",
            ProjectionExpression: "projects",
            TableName: "UserInfoTable"
        };
    
        event.response = {
            "claimsOverrideDetails": {
                "claimsToAddOrOverride": {
                    "userName": event.userName,
                    "projects": null
                },
            }
        };
    
        try {
            let result = await ddb.query(params).promise();
            if (result.Items.length > 0) {
                const projects = result.Items[0]["projects"]["S"];
                console.log("projects = " + projects);
                event.response.claimsOverrideDetails.claimsToAddOrOverride.projects = projects;
            }
        }
        catch (error) {
            console.log(error);
        }
    
        return event;
    };

    The code for the Lambda function is as follows.

  4. After a successful login, Amazon Cognito redirected to the URL that was specified in the App Client Settings section, and added the token to the URL.
  5. The webpage detected the token in the URL and displayed the Show Token Detail button. When you selected the button, the webpage read the token in the URL, decoded the token, and displayed the information in the relevant text boxes.
  6. Notice that the Decoded ID Token box shows the custom claim named projects that displays the projectID that was added by the PretokenGenerationLambdaFunction-pretokenCognito trigger.

How to use the sample code in your application

We recommend that you use this sample code with the following modifications:

  1. The code provided does not implement the API Gateway and Lambda functions that consume the custom claim information. You should implement the necessary Lambda functions and read the custom claim for the event object. This event object is a JSON-formatted object that contains authorization data.
  2. The ReactJS-based user interface should be hosted on an Amazon Simple Storage Service (Amazon S3) bucket.
  3. The projectId of the user is available in the token. Therefore, when the token is passed by the Authorization trigger to the back end, this custom claim information can be used to perform actions specific to the project for that user. For example, getting all of that user’s work items that are related to the project.
  4. Because the token is valid for one hour, the information in the custom claim information is available to the user interface during that time.
  5. You can use the AWS Amplify library to simplify the communication between your web application and Amazon Cognito. AWS Amplify can handle the token retention and refresh token mechanism for the web application. This also removes the need for the token to be displayed in the URL.
  6. If you’re using Amazon Cognito to manage your users and authenticate them, using the Amazon Cognito user pool to control access to your API is easier, because you don’t have to write the authentication code in your authorizer.
  7. If you decide to use Lambda authorizers, note the following important information from the topic Steps to create an API Gateway Lambda authorizer: “In production code, you may need to authenticate the user before granting authorization. If so, you can add authentication logic in the Lambda function as well by calling an authentication provider as directed in the documentation for that provider.”
  8. Lambda authorizer is recommended if the final authorization (not just token validity) decision is made based on custom claims.

Conclusion

In this blog post, we demonstrated how to implement fine-grained authorization based on data stored in the back end, by using claims stored in an identity token that is generated by the Amazon Cognito pre token generation trigger. This solution can help you achieve a reduction in latency and improvement in performance.

For more information on the pre token generation Lambda trigger, refer to 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.

Want more AWS Security news? Follow us on Twitter.

Ajit Ambike

Ajit Ambike

Ajit Ambike is a Sr. Application Architect at Amazon Web Services. As part of AWS Energy team, he leads the creation of new business capabilities for the customers. Ajit also brings best practices to the customers and partners that accelerate the productivity of their teams.

Zafar Kapadia

Zafar Kapadia

Zafar Kapadia is a Sr. Customer Delivery Architect at AWS. He has over 17 years of IT experience and has worked on several Application Development and Optimization projects. He is also an avid cricketer and plays in various local leagues.

Throttling a tiered, multi-tenant REST API at scale using API Gateway: Part 2

Post Syndicated from Nick Choi original https://aws.amazon.com/blogs/architecture/throttling-a-tiered-multi-tenant-rest-api-at-scale-using-api-gateway-part-2/

In Part 1 of this blog series, we demonstrated why tiering and throttling become necessary at scale for multi-tenant REST APIs, and explored tiering strategy and throttling with Amazon API Gateway.

In this post, Part 2, we will examine tenant isolation strategies at scale with API Gateway and extend the sample code from Part 1.

Enhancing the sample code

To enable this functionality in the sample code (Figure 1), we will make manual changes. First, create one API key for the Free Tier and five API keys for the Basic Tier. Currently, these API keys are private keys for your Amazon Cognito login, but we will make a further change in the backend business logic that will promote them to pooled resources. Note that all of these modifications are specific to this sample code’s implementation; the implementation and deployment of a production code may be completely different (Figure 1).

Cloud architecture of the sample code

Figure 1. Cloud architecture of the sample code

Next, in the business logic for thecreateKey(), find the AWS Lambda function in lambda/create_key.js.  It appears like this:

function createKey(tableName, key, plansTable, jwt, rand, callback) {
  const pool = getPoolForPlanId( key.planId ) 
  if (!pool) {
    createSiloedKey(tableName, key, plansTable, jwt, rand, callback);
  } else {
    createPooledKey(pool, tableName, key, jwt, callback);
  }
}

The getPoolForPlanId() function does a search for a pool of keys associated with the usage plan. If there is a pool, we “create” a kind of reference to the pooled resource, rather than a completely new key that is created by the API Gateway service directly. The lambda/api_key_pools.js should be empty.

exports.apiKeyPools = [];

In effect, all usage plans were considered as siloed keys up to now. To change that, populate the data structure with values from the six API keys that were created manually. You will have to look up the IDs of the API keys and usage plans that were created in API Gateway (Figures 2 and 3). Using the AWS console to navigate to API Gateway is the most intuitive.

A view of the AWS console when inspecting the ID for the Basic usage plan

Figure 2. A view of the AWS console when inspecting the ID for the Basic usage plan

A view of the AWS Console when looking up the API key value (not the ID)

Figure 3. A view of the AWS Console when looking up the API key value (not the ID)

When done, your code in lambda/api_key_pools.js should be the following, but instead of ellipses (), the IDs for the user plans and API keys specific to your environment will appear.

exports.apiKeyPools = [{
    planName: "FreePlan"
    planId: "...",
    apiKeys: [ "..." ]
  },
 {
    planName: "BasicPlan"
    planId: "...",
    apiKeys: [ "...", "...", "...", "...", "..." ]
  }];

After making the code changes, run cdk deploy from the command line to update the Lambda functions. This change will only affect key creation and deletion because of the system implementation. Updates affect only the user’s specific reference to the key, not the underlying resource managed by API Gateway.

When the web application is run now, it will look similar to before—tenants should not be aware what tiering strategy they have been assigned to. The only way to notice the difference would be to create two Free Tier keys, test them, and note that the value of the X-API-KEY header is unchanged between the two.

Now, you have a virtually unlimited number of users who can have API keys in the Free or Basic Tier. By keeping the Premium Tier siloed, you are subject to the 10,000-API-key maximum (less any keys allocated for the lower tiers). You may consider additional techniques to continue to scale, such as replicating your service in another AWS account.

Other production considerations

The sample code is minimal, and it illustrates just one aspect of scaling a Software-as-a-service (SaaS) application. There are many other aspects be considered in a production setting that we explore in this section.

The throttled endpoint, GET /api rely only on API key for authorization for demonstration purpose. For any production implementation consider authentication options for your REST APIs. You may explore and extend to require authentication with Cognito similar to /admin/* endpoints in the sample code.

One API key for Free Tier access and five API keys for Basic Tier access are illustrative in a sample code but not representative of production deployments. Number of API keys with service quota into consideration, business and technical decisions may be made to minimize noisy neighbor effect such as setting blast radius upper threshold of 0.1% of all users. To satisfy that requirement, each tier would need to spread users across at least 1,000 API keys. The number of keys allocated to Basic or Premium Tier would depend on market needs and pricing strategies. Additional allocations of keys could be held in reserve for troubleshooting, QA, tenant migrations, and key retirement.

In the planning phase of your solution, you will decide how many tiers to provide, how many usage plans are needed, and what throttle limits and quotas to apply. These decisions depend on your architecture and business.

To define API request limits, examine the system API Gateway is protecting and what load it can sustain. For example, if your service will scale up to 1,000 requests per second, it is possible to implement three tiers with a 10/50/40 split: the lowest tier shares one common API key with a 100 request per second limit; an intermediate tier has a pool of 25 API keys with a limit of 20 requests per second each; and the highest tier has a maximum of 10 API keys, each supporting 40 requests per second.

Metrics play a large role in continuously evolving your SaaS-tiering strategy (Figure 4). They provide rich insights into how tenants are using the system. Tenant-aware and SaaS-wide metrics on throttling and quota limits can be used to: assess tiering in-place, if tenants’ requirements are being met, and if currently used tenant usage profiles are valid (Figure 5).

Tiering strategy example with 3 tiers and requests allocation per tier

Figure 4. Tiering strategy example with 3 tiers and requests allocation per tier

An example SaaS metrics dashboard

Figure 5. An example SaaS metrics dashboard

API Gateway provides options for different levels of granularity required, including detailed metrics, and execution and access logging to enable observability of your SaaS solution. Granular usage metrics combined with underlying resource consumption leads to managing optimal experience for your tenants with throttling levels and policies per method and per client.

Cleanup

To avoid incurring future charges, delete the resources. This can be done on the command line by typing:

cd ${TOP}/cdk
cdk destroy

cd ${TOP}/react
amplify delete

${TOP} is the topmost directory of the sample code. For the most up-to-date information, see the README.md file.

Conclusion

In this two-part blog series, we have reviewed the best practices and challenges of effectively guarding a tiered multi-tenant REST API hosted in AWS API Gateway. We also explored how throttling policy and quota management can help you continuously evaluate the needs of your tenants and evolve your tiering strategy to protect your backend systems from being overwhelmed by inbound traffic.

Further reading:

Throttling a tiered, multi-tenant REST API at scale using API Gateway: Part 1

Post Syndicated from Nick Choi original https://aws.amazon.com/blogs/architecture/throttling-a-tiered-multi-tenant-rest-api-at-scale-using-api-gateway-part-1/

Many software-as-a-service (SaaS) providers adopt throttling as a common technique to protect a distributed system from spikes of inbound traffic that might compromise reliability, reduce throughput, or increase operational cost. Multi-tenant SaaS systems have an additional concern of fairness; excessive traffic from one tenant needs to be selectively throttled without impacting the experience of other tenants. This is also known as “the noisy neighbor” problem. AWS itself enforces some combination of throttling and quota limits on nearly all its own service APIs. SaaS providers building on AWS should design and implement throttling strategies in all of their APIs as well.

In this two-part blog series, we will explore tiering and throttling strategies for multi-tenant REST APIs and review tenant isolation models with hands-on sample code. In part 1, we will look at why a tiering and throttling strategy is needed and show how Amazon API Gateway can help by showing sample code. In part 2, we will dive deeper into tenant isolation models as well as considerations for production.

We selected Amazon API Gateway for this architecture since it is a fully managed service that helps developers to create, publish, maintain, monitor, and secure APIs. First, let’s focus on how Amazon API Gateway can be used to throttle REST APIs with fine granularity using Usage Plans and API Keys. Usage Plans define the thresholds beyond which throttling should occur. They also enable quotas, which sets a maximum usage per a day, week, or month. API Keys are identifiers for distinguishing traffic and determining which Usage Plans to apply for each request. We limit the scope of our discussion to REST APIs because other protocols that API Gateway supports — WebSocket APIs and HTTP APIs — have different throttling mechanisms that do not employ Usage Plans or API Keys.

SaaS providers must balance minimizing cost to serve and providing consistent quality of service for all tenants. They also need to ensure one tenant’s activity does not affect the other tenants’ experience. Throttling and quotas are a key aspect of a tiering strategy and important for protecting your service at any scale. In practice, this impact of throttling polices and quota management is continuously monitored and evaluated as the tenant composition and behavior evolve over time.

Architecture Overview

Figure 1. Cloud Architecture of the sample code.

Figure 1 – Architecture of the sample code

To get a firm foundation of the basics of throttling and quotas with API Gateway, we’ve provided sample code in AWS-Samples on GitHub. Not only does it provide a starting point to experiment with Usage Plans and API Keys in the API Gateway, but we will modify this code later to address complexity that happens at scale. The sample code has two main parts: 1) a web frontend and, 2) a serverless backend. The backend is a serverless architecture using Amazon API Gateway, AWS Lambda, Amazon DynamoDB, and Amazon Cognito. As Figure I illustrates, it implements one REST API endpoint, GET /api, that is protected with throttling and quotas. There are additional APIs under the /admin/* resource to provide Read access to Usage Plans, and CRUD operations on API Keys.

All these REST endpoints could be tested with developer tools such as curl or Postman, but we’ve also provided a web application, to help you get started. The web application illustrates how tenants might interact with the SaaS application to browse different tiers of service, purchase API Keys, and test them. The web application is implemented in React and uses AWS Amplify CLI and SDKs.

Prerequisites

To deploy the sample code, you should have the following prerequisites:

For clarity, we’ll use the environment variable, ${TOP}, to indicate the top-most directory in the cloned source code or the top directory in the project when browsing through GitHub.

Detailed instructions on how to install the code are in ${TOP}/INSTALL.md file in the code. After installation, follow the ${TOP}/WALKTHROUGH.md for step-by-step instructions to create a test key with a very small quota limit of 10 requests per day, and use the client to hit that limit. Search for HTTP 429: Too Many Requests as the signal your client has been throttled.

Figure 2: The web application (with browser developer tools enabled) shows that a quick succession of API calls starts returning an HTTP 429 after the quota for the day is exceeded.

Figure 2: The web application (with browser developer tools enabled) shows that a quick succession of API calls starts returning an HTTP 429 after the quota for the day is exceeded.

Responsibilities of the Client to support Throttling

The Client must provide an API Key in the header of the HTTP request, labelled, “X-Api-Key:”. If a resource in API Gateway has throttling enabled and that header is missing or invalid in the request, then API Gateway will reject the request.

Important: API Keys are simple identifiers, not authorization tokens or cryptographic keys. API keys are for throttling and managing quotas for tenants only and not suitable as a security mechanism. There are many ways to properly control access to a REST API in API Gateway, and we refer you to the AWS documentation for more details as that topic is beyond the scope of this post.

Clients should always test for the response to any network call, and implement logic specific to an HTTP 429 response. The correct action is almost always “try again later.” Just how much later, and how many times before giving up, is application dependent. Common approaches include:

  • Retry – With simple retry, client retries the request up to defined maximum retry limit configured
  • Exponential backoff – Exponential backoff uses progressively larger wait time between retries for consecutive errors. As the wait time can become very long quickly, maximum delay and a maximum retry limits should be specified.
  • Jitter – Jitter uses a random amount of delay between retry to prevent large bursts by spreading the request rate.

AWS SDK is an example client-responsibility implementation. Each AWS SDK implements automatic retry logic that uses a combination of retry, exponential backoff, jitter, and maximum retry limit.

SaaS Considerations: Tenant Isolation Strategies at Scale

While the sample code is a good start, the design has an implicit assumption that API Gateway will support as many API Keys as we have number of tenants. In fact, API Gateway has a quota on available per region per account. If the sample code’s requirements are to support more than 10,000 tenants (or if tenants are allowed multiple keys), then the sample implementation is not going to scale, and we need to consider more scalable implementation strategies.

This is one instance of a general challenge with SaaS called “tenant isolation strategies.” We highly recommend reviewing this white paper ‘SasS Tenant Isolation Strategies‘. A brief explanation here is that the one-resource-per-customer (or “siloed”) model is just one of many possible strategies to address tenant isolation. While the siloed model may be the easiest to implement and offers strong isolation, it offers no economy of scale, has high management complexity, and will quickly run into limits set by the underlying AWS Services. Other models besides siloed include pooling, and bridged models. Again, we recommend the whitepaper for more details.

Figure 3. Tiered multi-tenant architectures often employ different tenant isolation strategies at different tiers. Our example is specific to API Keys, but the technique generalizes to storage, compute, and other resources.

Figure 3- Tiered multi-tenant architectures often employ different tenant isolation strategies at different tiers. Our example is specific to API Keys, but the technique generalizes to storage, compute, and other resources.

In this example, we implement a range of tenant isolation strategies at different tiers of service. This allows us to protect against “noisy-neighbors” at the highest tier, minimize outlay of limited resources (namely, API-Keys) at the lowest tier, and still provide an effective, bounded “blast radius” of noisy neighbors at the mid-tier.

A concrete development example helps illustrate how this can be implemented. Assume three tiers of service: Free, Basic, and Premium. One could create a single API Key that is a pooled resource among all tenants in the Free Tier. At the other extreme, each Premium customer would get their own unique API Key. They would protect Premium tier tenants from the ‘noisy neighbor’ effect. In the middle, the Basic tenants would be evenly distributed across a set of fixed keys. This is not complete isolation for each tenant, but the impact of any one tenant is contained within “blast radius” defined.

In production, we recommend a more nuanced approach with additional considerations for monitoring and automation to continuously evaluate tiering strategy. We will revisit these topics in greater detail after considering the sample code.

Conclusion

In this post, we have reviewed how to effectively guard a tiered multi-tenant REST API hosted in Amazon API Gateway. We also explored how tiering and throttling strategies can influence tenant isolation models. In Part 2 of this blog series, we will dive deeper into tenant isolation models and gaining insights with metrics.

If you’d like to know more about the topic, the AWS Well-Architected SaaS Lens Performance Efficiency pillar dives deep on tenant tiers and providing differentiated levels of performance to each tier. It also provides best practices and resources to help you design and reduce impact of noisy neighbors your SaaS solution.

To learn more about Serverless SaaS architectures in general, we recommend the AWS Serverless SaaS Workshop and the SaaS Factory Serverless SaaS reference solution that inspired it.

Best practices: Securing your Amazon Location Service resources

Post Syndicated from Dave Bailey original https://aws.amazon.com/blogs/security/best-practices-securing-your-amazon-location-service-resources/

Location data is subjected to heavy scrutiny by security experts. Knowing the current position of a person, vehicle, or asset can provide industries with many benefits, whether to understand where a current delivery is, how many people are inside a venue, or to optimize routing for a fleet of vehicles. This blog post explains how Amazon Web Services (AWS) helps keep location data secured in transit and at rest, and how you can leverage additional security features to help keep information safe and compliant.

The General Data Protection Regulation (GDPR) defines personal data as “any information relating to an identified or identifiable natural person (…) such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person.” Also, many companies wish to improve transparency to users, making it explicit when a particular application wants to not only track their position and data, but also to share that information with other apps and websites. Your organization needs to adapt to these changes quickly to maintain a secure stance in a competitive environment.

On June 1, 2021, AWS made Amazon Location Service generally available to customers. With Amazon Location, you can build applications that provide maps and points of interest, convert street addresses into geographic coordinates, calculate routes, track resources, and invoke actions based on location. The service enables you to access location data with developer tools and to move your applications to production faster with monitoring and management capabilities.

In this blog post, we will show you the features that Amazon Location provides out of the box to keep your data safe, along with best practices that you can follow to reach the level of security that your organization strives to accomplish.

Data control and data rights

Amazon Location relies on global trusted providers Esri and HERE Technologies to provide high-quality location data to customers. Features like maps, places, and routes are provided by these AWS Partners so solutions can have data that is not only accurate but constantly updated.

AWS anonymizes and encrypts location data at rest and during its transmission to partner systems. In parallel, third parties cannot sell your data or use it for advertising purposes, following our service terms. This helps you shield sensitive information, protect user privacy, and reduce organizational compliance risks. To learn more, see the Amazon Location Data Security and Control documentation.

Integrations

Operationalizing location-based solutions can be daunting. It’s not just necessary to build the solution, but also to integrate it with the rest of your applications that are built in AWS. Amazon Location facilitates this process from a security perspective by integrating with services that expedite the development process, enhancing the security aspects of the solution.

Encryption

Amazon Location uses AWS owned keys by default to automatically encrypt personally identifiable data. AWS owned keys are a collection of AWS Key Management Service (AWS KMS) keys that an AWS service owns and manages for use in multiple AWS accounts. Although AWS owned keys are not in your AWS account, Amazon Location can use the associated AWS owned keys to protect the resources in your account.

If customers choose to use their own keys, they can benefit from AWS KMS to store their own encryption keys and use them to add a second layer of encryption to geofencing and tracking data.

Authentication and authorization

Amazon Location also integrates with AWS Identity and Access Management (IAM), so that you can use its identity-based policies to specify allowed or denied actions and resources, as well as the conditions under which actions are allowed or denied on Amazon Location. Also, for actions that require unauthenticated access, you can use unauthenticated IAM roles.

As an extension to IAM, Amazon Cognito can be an option if you need to integrate your solution with a front-end client that authenticates users with its own process. In this case, you can use Cognito to handle the authentication, authorization, and user management for you. You can use Cognito unauthenticated identity pools with Amazon Location as a way for applications to retrieve temporary, scoped-down AWS credentials. To learn more about setting up Cognito with Amazon Location, see the blog post Add a map to your webpage with Amazon Location Service.

Limit the scope of your unauthenticated roles to a domain

When you are building an application that allows users to perform actions such as retrieving map tiles, searching for points of interest, updating device positions, and calculating routes without needing them to be authenticated, you can make use of unauthenticated roles.

When using unauthenticated roles to access Amazon Location resources, you can add an extra condition to limit resource access to an HTTP referer that you specify in the policy. The aws:referer request context value is provided by the caller in an HTTP header, and it is included in a web browser request.

The following is an example of a policy that allows access to a Map resource by using the aws:referer condition, but only if the request comes from the domain example.com.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "MapsReadOnly",
      "Effect": "Allow",
      "Action": [
        "geo:GetMapStyleDescriptor",
        "geo:GetMapGlyphs",
        "geo:GetMapSprites",
        "geo:GetMapTile"
      ],
      "Resource": "arn:aws:geo:us-west-2:111122223333:map/MyMap",
      "Condition": {
        "StringLike": {
          "aws:Referer": "https://www.example.com/*"
        }
      }
    }
  ]
}

To learn more about aws:referer and other global conditions, see AWS global condition context keys.

Encrypt tracker and geofence information using customer managed keys with AWS KMS

When you create your tracker and geofence collection resources, you have the option to use a symmetric customer managed key to add a second layer of encryption to geofencing and tracking data. Because you have full control of this key, you can establish and maintain your own IAM policies, manage key rotation, and schedule keys for deletion.

After you create your resources with customer managed keys, the geometry of your geofences and all positions associated to a tracked device will have two layers of encryption. In the next sections, you will see how to create a key and use it to encrypt your own data.

Create an AWS KMS symmetric key

First, you need to create a key policy that will limit the AWS KMS key to allow access to principals authorized to use Amazon Location and to principals authorized to manage the key. For more information about specifying permissions in a policy, see the AWS KMS Developer Guide.

To create the key policy

Create a JSON policy file by using the following policy as a reference. This key policy allows Amazon Location to grant access to your KMS key only when it is called from your AWS account. This works by combining the kms:ViaService and kms:CallerAccount conditions. In the following policy, replace us-west-2 with your AWS Region of choice, and the kms:CallerAccount value with your AWS account ID. Adjust the KMS Key Administrators statement to reflect your actual key administrators’ principals, including yourself. For details on how to use the Principal element, see the AWS JSON policy elements documentation.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "Amazon Location",
      "Effect": "Allow",
      "Principal": {
        "AWS": "*"
      },
      "Action": [
        "kms:DescribeKey",
        "kms:CreateGrant"
      ],
      "Resource": "*",
      "Condition": {
        "StringEquals": {
          "kms:ViaService": "geo.us-west-2.amazonaws.com",
          "kms:CallerAccount": "111122223333"
        }
      }
    },
    {
      "Sid": "Allow access for Key Administrators",
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::111122223333:user/KMSKeyAdmin"
      },
      "Action": [
        "kms:Create*",
        "kms:Describe*",
        "kms:Enable*",
        "kms:List*",
        "kms:Put*",
        "kms:Update*",
        "kms:Revoke*",
        "kms:Disable*",
        "kms:Get*",
        "kms:Delete*",
        "kms:TagResource",
        "kms:UntagResource",
        "kms:ScheduleKeyDeletion",
        "kms:CancelKeyDeletion"
      ],
      "Resource": "*"
    }
  ]
}

For the next steps, you will use the AWS Command Line Interface (AWS CLI). Make sure to have the latest version installed by following the AWS CLI documentation.

Tip: AWS CLI will consider the Region you defined as the default during the configuration steps, but you can override this configuration by adding –region <your region> at the end of each command line in the following command. Also, make sure that your user has the appropriate permissions to perform those actions.

To create the symmetric key

Now, create a symmetric key on AWS KMS by running the create-key command and passing the policy file that you created in the previous step.

aws kms create-key –policy file://<your JSON policy file>

Alternatively, you can create the symmetric key using the AWS KMS console with the preceding key policy.

After running the command, you should see the following output. Take note of the KeyId value.

{
  "KeyMetadata": {
    "Origin": "AWS_KMS",
    "KeyId": "1234abcd-12ab-34cd-56ef-1234567890ab",
    "Description": "",
    "KeyManager": "CUSTOMER",
    "Enabled": true,
    "CustomerMasterKeySpec": "SYMMETRIC_DEFAULT",
    "KeyUsage": "ENCRYPT_DECRYPT",
    "KeyState": "Enabled",
    "CreationDate": 1502910355.475,
    "Arn": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab",
    "AWSAccountId": "111122223333",
    "MultiRegion": false
    "EncryptionAlgorithms": [
      "SYMMETRIC_DEFAULT"
    ],
  }
}

Create an Amazon Location tracker and geofence collection resources

To create an Amazon Location tracker resource that uses AWS KMS for a second layer of encryption, run the following command, passing the key ID from the previous step.

aws location \
	create-tracker \
	--tracker-name "MySecureTracker" \
	--kms-key-id "1234abcd-12ab-34cd-56ef-1234567890ab"

Here is the output from this command.

{
    "CreateTime": "2021-07-15T04:54:12.913000+00:00",
    "TrackerArn": "arn:aws:geo:us-west-2:111122223333:tracker/MySecureTracker",
    "TrackerName": "MySecureTracker"
}

Similarly, to create a geofence collection by using your own KMS symmetric keys, run the following command, also modifying the key ID.

aws location \
	create-geofence-collection \
	--collection-name "MySecureGeofenceCollection" \
	--kms-key-id "1234abcd-12ab-34cd-56ef-1234567890ab"

Here is the output from this command.

{
    "CreateTime": "2021-07-15T04:54:12.913000+00:00",
    "TrackerArn": "arn:aws:geo:us-west-2:111122223333:geofence-collection/MySecureGeoCollection",
    "TrackerName": "MySecureGeoCollection"
}

By following these steps, you have added a second layer of encryption to your geofence collection and tracker.

Data retention best practices

Trackers and geofence collections are stored and never leave your AWS account without your permission, but they have different lifecycles on Amazon Location.

Trackers store the positions of devices and assets that are tracked in a longitude/latitude format. These positions are stored for 30 days by the service before being automatically deleted. If needed for historical purposes, you can transfer this data to another data storage layer and apply the proper security measures based on the shared responsibility model.

Geofence collections store the geometries you provide until you explicitly choose to delete them, so you can use encryption with AWS managed keys or your own keys to keep them for as long as needed.

Asset tracking and location storage best practices

After a tracker is created, you can start sending location updates by using the Amazon Location front-end SDKs or by calling the BatchUpdateDevicePosition API. In both cases, at a minimum, you need to provide the latitude and longitude, the time when the device was in that position, and a device-unique identifier that represents the asset being tracked.

Protecting device IDs

This device ID can be any string of your choice, so you should apply measures to prevent certain IDs from being used. Some examples of what to avoid include:

  • First and last names
  • Facility names
  • Documents, such as driver’s licenses or social security numbers
  • Emails
  • Addresses
  • Telephone numbers

Latitude and longitude precision

Latitude and longitude coordinates convey precision in degrees, presented as decimals, with each decimal place representing a different measure of distance (when measured at the equator).

Amazon Location supports up to six decimal places of precision (0.000001), which is equal to approximately 11 cm or 4.4 inches at the equator. You can limit the number of decimal places in the latitude and longitude pair that is sent to the tracker based on the precision required, increasing the location range and providing extra privacy to users.

Figure 1 shows a latitude and longitude pair, with the level of detail associated to decimals places.

Figure 1: Geolocation decimal precision details

Figure 1: Geolocation decimal precision details

Position filtering

Amazon Location introduced position filtering as an option to trackers that enables cost reduction and reduces jitter from inaccurate device location updates.

  • DistanceBased filtering ignores location updates wherein devices have moved less than 30 meters (98.4 ft).
  • TimeBased filtering evaluates every location update against linked geofence collections, but not every location update is stored. If your update frequency is more often than 30 seconds, then only one update per 30 seconds is stored for each unique device ID.
  • AccuracyBased filtering ignores location updates if the distance moved was less than the measured accuracy provided by the device.

By using filtering options, you can reduce the number of location updates that are sent and stored, thus reducing the level of location detail provided and increasing the level of privacy.

Logging and monitoring

Amazon Location integrates with AWS services that provide the observability needed to help you comply with your organization’s security standards.

To record all actions that were taken by users, roles, or AWS services that access Amazon Location, consider using AWS CloudTrail. CloudTrail provides information on who is accessing your resources, detailing the account ID, principal ID, source IP address, timestamp, and more. Moreover, Amazon CloudWatch helps you collect and analyze metrics related to your Amazon Location resources. CloudWatch also allows you to create alarms based on pre-defined thresholds of call counts. These alarms can create notifications through Amazon Simple Notification Service (Amazon SNS) to automatically alert teams responsible for investigating abnormalities.

Conclusion

At AWS, security is our top priority. Here, security and compliance is a shared responsibility between AWS and the customer, where AWS is responsible for protecting the infrastructure that runs all of the services offered in the AWS Cloud. The customer assumes the responsibility to perform all of the necessary security configurations to the solutions they are building on top of our infrastructure.

In this blog post, you’ve learned the controls and guardrails that Amazon Location provides out of the box to help provide data privacy and data protection to our customers. You also learned about the other mechanisms you can use to enhance your security posture.

Start building your own secure geolocation solutions by following the Amazon Location Developer Guide and learn more about how the service handles security by reading the security topics in the guide.

 
If you have feedback about this post, submit comments in the Comments section below. If you have questions about this blog post, start a new thread on Amazon Location Service forum or contact AWS Support.

Want more AWS Security news? Follow us on Twitter.

Rafael Leandro Junior

Rafael Leandro, Junior

Rafael Leandro, Junior, is a senior global solutions architect who currently focuses on the consumer packaged goods and transportation industries. He helps large global customers on their journeys with AWS.

David Bailey

David Bailey

David Bailey is a senior security consultant who helps AWS customers achieve their cloud security goals. He has a passion for building new technologies and providing mentorship for others.