Tag Archives: vulnerabilities

CVE-2022-47929: traffic control noqueue no problem?

Post Syndicated from Frederick Lawler original https://blog.cloudflare.com/cve-2022-47929-traffic-control-noqueue-no-problem/

CVE-2022-47929: traffic control noqueue no problem?

CVE-2022-47929: traffic control noqueue no problem?

USER namespaces power the functionality of our favorite tools such as docker, podman, and kubernetes. We wrote about Linux namespaces back in June and explained them like this:

Most of the namespaces are uncontroversial, like the UTS namespace which allows the host system to hide its hostname and time. Others are complex but straightforward – NET and NS (mount) namespaces are known to be hard to wrap your head around. Finally, there is this very special, very curious USER namespace. USER namespace is special since it allows the – typically unprivileged owner to operate as “root” inside it. It’s a foundation to having tools like Docker to not operate as true root, and things like rootless containers.

Due to its nature, allowing unprivileged users access to USER namespace always carried a great security risk. With its help the unprivileged user can in fact run code that typically requires root. This code is often under-tested and buggy. Today we will look into one such case where USER namespaces are leveraged to exploit a kernel bug that can result in an unprivileged denial of service attack.

Enter Linux Traffic Control queue disciplines

In 2019, we were exploring leveraging Linux Traffic Control’s queue discipline (qdisc) to schedule packets for one of our services with the Hierarchy Token Bucket (HTB) classful qdisc strategy. Linux Traffic Control is a user-configured system to schedule and filter network packets. Queue disciplines are the strategies in which packets are scheduled. In particular, we wanted to filter and schedule certain packets from an interface, and drop others into the noqueue qdisc.

noqueue is a special case qdisc, such that packets are supposed to be dropped when scheduled into it. In practice, this is not the case. Linux handles noqueue such that packets are passed through and not dropped (for the most part). The documentation states as much. It also states that “It is not possible to assign the noqueue queuing discipline to physical devices or classes.” So what happens when we assign noqueue to a class?

Let’s write some shell commands to show the problem in action:

1. $ sudo -i
2. # dev=enp0s5
3. # tc qdisc replace dev $dev root handle 1: htb default 1
4. # tc class add dev $dev parent 1: classid 1:1 htb rate 10mbit
5. # tc qdisc add dev $dev parent 1:1 handle 10: noqueue

  1. First we need to log in as root because that gives us CAP_NET_ADMIN to be able to configure traffic control.
  2. We then assign a network interface to a variable. These can be found with ip a. Virtual interfaces can be located by calling ls /sys/devices/virtual/net. These will match with the output from ip a.
  3. Our interface is currently assigned to the pfifo_fast qdisc, so we replace it with the HTB classful qdisc and assign it the handle of 1:. We can think of this as the root node in a tree. The “default 1” configures this such that unclassified traffic will be routed directly through this qdisc which falls back to pfifo_fast queuing. (more on this later)
  4. Next we add a class to our root qdisc 1:, assign it to the first leaf node 1 of root 1: 1:1, and give it some reasonable configuration defaults.
  5. Lastly, we add the noqueue qdisc to our first leaf node in the hierarchy: 1:1. This effectively means traffic routed here will be scheduled to noqueue

Assuming our setup executed without a hitch, we will receive something similar to this kernel panic:

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
Call Trace:

We know that the root user is responsible for setting qdisc on interfaces, so if root can crash the kernel, so what? We just do not apply noqueue qdisc to a class id of a HTB qdisc:

# dev=enp0s5
# tc qdisc replace dev $dev root handle 1: htb default 1
# tc class add dev $dev parent 1: classid 1:2 htb rate 10mbit // A
// B is missing, so anything not filtered into 1:2 will be pfifio_fast

Here, we leveraged the default case of HTB where we assign a class id 1:2 to be rate-limited (A), and implicitly did not set a qdisc to another class such as id 1:1 (B). Packets queued to (A) will be filtered to HTB_DIRECT and packets queued to (B) will be filtered into pfifo_fast.

Because we were not familiar with this part of the codebase, we notified the mailing lists and created a ticket. The bug did not seem all that important to us at that time.

Fast-forward to 2022, we are pushing USER namespace creation hardening. We extended the Linux LSM framework with a new LSM hook: userns_create to leverage eBPF LSM for our protections, and encourage others to do so as well. Recently while combing our ticket backlog, we rethought this bug. We asked ourselves, “can we leverage USER namespaces to trigger the bug?” and the short answer is yes!

Demonstrating the bug

The exploit can be performed with any classful qdisc that assumes a struct Qdisc.enqueue function to not be NULL (more on this later), but in this case, we are demonstrating just with HTB.

$ unshare -rU –net
$ dev=lo
$ tc qdisc replace dev $dev root handle 1: htb default 1
$ tc class add dev $dev parent 1: classid 1:1 htb rate 10mbit
$ tc qdisc add dev $dev parent 1:1 handle 10: noqueue
$ ping -I $dev -w 1 -c 1

We use the “lo” interface to demonstrate that this bug is triggerable with a virtual interface. This is important for containers because they are fed virtual interfaces most of the time, and not the physical interface. Because of that, we can use a container to crash the host as an unprivileged user, and thus perform a denial of service attack.

Why does that work?

To understand the problem a bit better, we need to look back to the original patch series, but specifically this commit that introduced the bug. Before this series, achieving noqueue on interfaces relied on a hack that would set a device qdisc to noqueue if the device had a tx_queue_len = 0. The commit d66d6c3152e8 (“net: sched: register noqueue qdisc”) circumvents this by explicitly allowing noqueue to be added with the tc command without needing to get around that limitation.

The way the kernel checks for whether we are in a noqueue case or not, is to simply check if a qdisc has a NULL enqueue() function. Recall from earlier that noqueue does not necessarily drop packets in practice? After that check in the fail case, the following logic handles the noqueue functionality. In order to fail the check, the author had to cheat a reassignment from noop_enqueue() to NULL by making enqueue = NULL in the init which is called way after register_qdisc() during runtime.

Here is where classful qdiscs come into play. The check for an enqueue function is no longer NULL. In this call path, it is now set to HTB (in our example) and is thus allowed to enqueue the struct skb to a queue by making a call to the function htb_enqueue(). Once in there, HTB performs a lookup to pull in a qdisc assigned to a leaf node, and eventually attempts to queue the struct skb to the chosen qdisc which ultimately reaches this function:


static inline int qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch,
				struct sk_buff **to_free)
	qdisc_calculate_pkt_len(skb, sch);
	return sch->enqueue(skb, sch, to_free); // sch->enqueue == NULL

We can see that the enqueueing process is fairly agnostic from physical/virtual interfaces. The permissions and validation checks are done when adding a queue to an interface, which is why the classful qdics assume the queue to not be NULL. This knowledge leads us to a few solutions to consider.


We had a few solutions ranging from what we thought was best to worst:

  1. Follow tc-noqueue documentation and do not allow noqueue to be assigned to a classful qdisc
  2. Instead of checking for NULL, check for struct noqueue_qdisc_ops, and reset noqueue to back to noop_enqueue
  3. For each classful qdisc, check for NULL and fallback

While we ultimately went for the first option: “disallow noqueue for qdisc classes”, the third option creates a lot of churn in the code, and does not solve the problem completely. Future qdiscs implementations could forget that important check as well as the maintainers. However, the reason for passing on the second option is a bit more interesting.

The reason we did not follow that approach is because we need to first answer these questions:

Why not allow noqueue for classful qdiscs?

This contradicts the documentation. The documentation does have some precedent for not being totally followed in practice, but we will need to update that to reflect the current state. This is fine to do, but does not address the behavior change problem other than remove the NULL dereference bug.

What behavior changes if we do allow noqueue for qdiscs?

This is harder to answer because we need to determine what that behavior should be. Currently, when noqueue is applied as the root qdisc for an interface, the path is to essentially allow packets to be processed. Claiming a fallback for classes is a different matter. They may each have their own fallback rules, and how do we know what is the right fallback? Sometimes in HTB the fallback is pass-through with HTB_DIRECT, sometimes it is pfifo_fast. What about the other classes? Perhaps instead we should fall back to the default noqueue behavior as it is for root qdiscs?

We felt that going down this route would only add confusion and additional complexity to queuing. We could also make an argument that such a change could be considered a feature addition and not necessarily a bug fix. Suffice it to say, adhering to the current documentation seems to be the more appealing approach to prevent the vulnerability now, while something else can be worked out later.


First and foremost, apply this patch as soon as possible. And consider hardening USER namespaces on your systems by setting sysctl -w kernel.unprivileged_userns_clone=0, which only lets root create USER namespaces in Debian kernels, sysctl -w user.max_user_namespaces=[number] for a process hierarchy, or consider backporting these two patches: security_create_user_ns() and the SELinux implementation  (now in Linux 6.1.x) to allow you to protect your systems with either eBPF or SELinux. If you are sure you’re not using USER namespaces and in extreme cases, you might consider turning the feature off with CONFIG_USERNS=n. This is just one example of many where namespaces are leveraged to perform an attack, and more are surely to crop up in varying levels of severity in the future.

Special thanks to Ignat Korchagin and Jakub Sitnicki for code reviews and helping demonstrate the bug in practice.

Security Analysis of Threema

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2023/01/security-analysis-of-threema.html

A group of Swiss researchers have published an impressive security analysis of Threema.

We provide an extensive cryptographic analysis of Threema, a Swiss-based encrypted messaging application with more than 10 million users and 7000 corporate customers. We present seven different attacks against the protocol in three different threat models. As one example, we present a cross-protocol attack which breaks authentication in Threema and which exploits the lack of proper key separation between different sub-protocols. As another, we demonstrate a compression-based side-channel attack that recovers users’ long-term private keys through observation of the size of Threema encrypted back-ups. We discuss remediations for our attacks and draw three wider lessons for developers of secure protocols.

From a news article:

Threema has more than 10 million users, which include the Swiss government, the Swiss army, German Chancellor Olaf Scholz, and other politicians in that country. Threema developers advertise it as a more secure alternative to Meta’s WhatsApp messenger. It’s among the top Android apps for a fee-based category in Switzerland, Germany, Austria, Canada, and Australia. The app uses a custom-designed encryption protocol in contravention of established cryptographic norms.

The company is performing the usual denials and deflections:

In a web post, Threema officials said the vulnerabilities applied to an old protocol that’s no longer in use. It also said the researchers were overselling their findings.

“While some of the findings presented in the paper may be interesting from a theoretical standpoint, none of them ever had any considerable real-world impact,” the post stated. “Most assume extensive and unrealistic prerequisites that would have far greater consequences than the respective finding itself.”

Left out of the statement is that the protocol the researchers analyzed is old because they disclosed the vulnerabilities to Threema, and Threema updated it.

Critical Microsoft Code-Execution Vulnerability

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/12/critical-microsoft-code-execution-vulnerability.html

A critical code-execution vulnerability in Microsoft Windows was patched in September. It seems that researchers just realized how serious it was (and is):

Like EternalBlue, CVE-2022-37958, as the latest vulnerability is tracked, allows attackers to execute malicious code with no authentication required. Also, like EternalBlue, it’s wormable, meaning that a single exploit can trigger a chain reaction of self-replicating follow-on exploits on other vulnerable systems. The wormability of EternalBlue allowed WannaCry and several other attacks to spread across the world in a matter of minutes with no user interaction required.

But unlike EternalBlue, which could be exploited when using only the SMB, or server message block, a protocol for file and printer sharing and similar network activities, this latest vulnerability is present in a much broader range of network protocols, giving attackers more flexibility than they had when exploiting the older vulnerability.


Microsoft fixed CVE-2022-37958 in September during its monthly Patch Tuesday rollout of security fixes. At the time, however, Microsoft researchers believed the vulnerability allowed only the disclosure of potentially sensitive information. As such, Microsoft gave the vulnerability a designation of “important.” In the routine course of analyzing vulnerabilities after they’re patched, Palmiotti discovered it allowed for remote code execution in much the way EternalBlue did. Last week, Microsoft revised the designation to critical and gave it a severity rating of 8.1, the same given to EternalBlue.

A Security Vulnerability in the KmsdBot Botnet

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/12/a-security-vulnerability-in-the-kmsdbot-botnet.html

Security researchers found a software bug in the KmsdBot cryptomining botnet:

With no error-checking built in, sending KmsdBot a malformed command­—like its controllers did one day while Akamai was watching­—created a panic crash with an “index out of range” error. Because there’s no persistence, the bot stays down, and malicious agents would need to reinfect a machine and rebuild the bot’s functions. It is, as Akamai notes, “a nice story” and “a strong example of the fickle nature of technology.”

Security Vulnerabilities in Eufy Cameras

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/12/security-vulnerabilities-in-eufy-cameras.html

Eufy cameras claim to be local only, but upload data to the cloud. The company is basically lying to reporters, despite being shown evidence to the contrary. The company’s behavior is so egregious that ReviewGeek is no longer recommending them.

This will be interesting to watch. If Eufy can ignore security researchers and the press without there being any repercussions in the market, others will follow suit. And we will lose public shaming as an incentive to improve security.


After further testing, we’re not seeing the VLC streams begin based solely on the camera detecting motion. We’re not sure if that’s a change since yesterday or something I got wrong in our initial report. It does appear that Eufy is making changes—it appears to have removed access to the method we were using to get the address of our streams, although an address we already obtained is still working.

Sirius XM Software Vulnerability

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/12/sirius-xm-software-vulnerability.html

This is new:

Newly revealed research shows that a number of major car brands, including Honda, Nissan, Infiniti, and Acura, were affected by a previously undisclosed security bug that would have allowed a savvy hacker to hijack vehicles and steal user data. According to researchers, the bug was in the car’s Sirius XM telematics infrastructure and would have allowed a hacker to remotely locate a vehicle, unlock and start it, flash the lights, honk the horn, pop the trunk, and access sensitive customer info like the owner’s name, phone number, address, and vehicle details.

Cars are just computers with four wheels and an engine. It’s no surprise that the software is vulnerable, and that everything is connected.

Failures in Twitter’s Two-Factor Authentication System

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/11/failures-in-twitters-two-factor-authentication-system.html

Twitter is having intermittent problems with its two-factor authentication system:

Not all users are having problems receiving SMS authentication codes, and those who rely on an authenticator app or physical authentication token to secure their Twitter account may not have reason to test the mechanism. But users have been self-reporting issues on Twitter since the weekend, and WIRED confirmed that on at least some accounts, authentication texts are hours delayed or not coming at all. The meltdown comes less than two weeks after Twitter laid off about half of its workers, roughly 3,700 people. Since then, engineers, operations specialists, IT staff, and security teams have been stretched thin attempting to adapt Twitter’s offerings and build new features per new owner Elon Musk’s agenda.

On top of that, it seems that the system has a new vulnerability:

A researcher contacted Information Security Media Group on condition of anonymity to reveal that texting “STOP” to the Twitter verification service results in the service turning off SMS two-factor authentication.

“Your phone has been removed and SMS 2FA has been disabled from all accounts,” is the automated response.

The vulnerability, which ISMG verified, allows a hacker to spoof the registered phone number to disable two-factor authentication. That potentially exposes accounts to a password reset attack or account takeover through password stuffing.

This is not a good sign.

Cloudflare is not affected by the OpenSSL vulnerabilities CVE-2022-3602 and CVE-2022-37

Post Syndicated from Evan Johnson original https://blog.cloudflare.com/cloudflare-is-not-affected-by-the-openssl-vulnerabilities-cve-2022-3602-and-cve-2022-37/

Cloudflare is not affected by the OpenSSL vulnerabilities CVE-2022-3602 and CVE-2022-37

Cloudflare is not affected by the OpenSSL vulnerabilities CVE-2022-3602 and CVE-2022-37

Yesterday, November 1, 2022, OpenSSL released version 3.0.7 to patch CVE-2022-3602 and CVE-2022-3786, two HIGH risk vulnerabilities in the OpenSSL 3.0.x cryptographic library. Cloudflare is not affected by these vulnerabilities because we use BoringSSL in our products.

These vulnerabilities are memory corruption issues, in which attackers may be able to execute arbitrary code on a victim’s machine. CVE-2022-3602 was initially announced as a CRITICAL severity vulnerability, but it was downgraded to HIGH because it was deemed difficult to exploit with remote code execution (RCE). Unlike previous situations where users of OpenSSL were almost universally vulnerable, software that is using other versions of OpenSSL (like 1.1.1) are not vulnerable to this attack.

How do these issues affect clients and servers?

These vulnerabilities reside in the code responsible for X.509 certificate verification – most often executed on the client side to authenticate the server and the certificate presented. In order to be impacted by this vulnerability the victim (client or server) needs a few conditions to be true:

  • A malicious certificate needs to be signed by a Certificate Authority that the victim trusts.
  • The victim needs to validate the malicious certificate or ignore a series of warnings from the browser.
  • The victim needs to be running OpenSSL 3.0.x before 3.0.7.

For a client to be affected by this vulnerability, they would have to visit a malicious site that presents a certificate containing an exploit payload. In addition, this malicious certificate would have to be signed by a trusted certificate authority (CA).

Servers with a vulnerable version of OpenSSL can be attacked if they support mutual authentication – a scenario where both client and a server provide a valid and signed X.509 certificate, and the client is able to present a certificate with an exploit payload to the server.

How should you handle this issue?

If you’re managing services that run OpenSSL: you should patch vulnerable OpenSSL packages. On a Linux system you can determine if you have any processes dynamically loading OpenSSL with the lsof command. Here’s an example of finding OpenSSL being used by NGINX.

[email protected]:/# lsof | grep libssl.so.3
nginx   1294     root  mem       REG              254,1           925009 /usr/lib/x86_64-linux-gnu/libssl.so.3 (path dev=0,142)

Once the package maintainers for your Linux distro release OpenSSL 3.0.7 you can patch by updating your package sources and upgrading the libssl3 package. On Debian and Ubuntu this can be done with the apt-get upgrade command

[email protected]:/# apt-get --only-upgrade install libssl3

With that said, it’s possible that you could be running a vulnerable version of OpenSSL that the lsof command can’t find because your process is statically compiled. It’s important to update your statically compiled software that you are responsible for maintaining, and make sure that over the coming days you are updating your operating system and other installed software that might contain the vulnerable OpenSSL versions.

Key takeaways

Cloudflare’s use of BoringSSL helped us be confident that the issue would not impact us prior to the release date of the vulnerabilities.

More generally, the vulnerability is a reminder that memory safety is still an important issue. This issue may be difficult to exploit because it requires a maliciously crafted certificate that is signed by a trusted CA, and certificate issuers are likely to begin validating that the certificates they sign don’t contain payloads that exploit these vulnerabilities.  However, it’s still important to patch your software and upgrade your vulnerable OpenSSL packages to OpenSSL 3.0.7 given the severity of the issue.

To learn more about our mission to help build a better Internet, start here. If you’re looking for a new career direction, check out our open positions.

Critical Vulnerability in Open SSL

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/10/critical-vulnerability-in-open-ssl.html

There are no details yet, but it’s really important that you patch Open SSL 3.x when the new version comes out on Tuesday.

How bad is “Critical”? According to OpenSSL, an issue of critical severity affects common configurations and is also likely exploitable.

It’s likely to be abused to disclose server memory contents, and potentially reveal user details, and could be easily exploited remotely to compromise server private keys or execute code execute remotely. In other words, pretty much everything you don’t want happening on your production systems.

Slashdot thread.

Relay Attack against Teslas

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/09/relay-attack-against-teslas.html

Nice work:

Radio relay attacks are technically complicated to execute, but conceptually easy to understand: attackers simply extend the range of your existing key using what is essentially a high-tech walkie-talkie. One thief stands near you while you’re in the grocery store, intercepting your key’s transmitted signal with a radio transceiver. Another stands near your car, with another transceiver, taking the signal from their friend and passing it on to the car. Since the car and the key can now talk, through the thieves’ range extenders, the car has no reason to suspect the key isn’t inside—and fires right up.

But Tesla’s credit card keys, like many digital keys stored in cell phones, don’t work via radio. Instead, they rely on a different protocol called Near Field Communication or NFC. Those keys had previously been seen as more secure, since their range is so limited and their handshakes with cars are more complex.

Now, researchers seem to have cracked the code. By reverse-engineering the communications between a Tesla Model Y and its credit card key, they were able to properly execute a range-extending relay attack against the crossover. While this specific use case focuses on Tesla, it’s a proof of concept—NFC handshakes can, and eventually will, be reverse-engineered.

Responsible Disclosure for Cryptocurrency Security

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/09/responsible-disclosure-for-cryptocurrency-security.html

Stewart Baker discusses why the industry-norm responsible disclosure for software vulnerabilities fails for cryptocurrency software.

Why can’t the cryptocurrency industry solve the problem the way the software and hardware industries do, by patching and updating security as flaws are found? Two reasons: First, many customers don’t have an ongoing relationship with the hardware and software providers that protect their funds­—nor do they have an incentive to update security on a regular basis. Turning to a new security provider or using updated software creates risks; leaving everything the way it was feels safer. So users won’t be rushing to pay for and install new security patches.

Second, cryptocurrency is famously and deliberately decentralized, anonymized, and low friction. That means that the company responsible for hardware or software security may have no way to identify who used its product, or to get the patch to those users. It also means that many wallets with security flaws will be publicly accessible, protected only by an elaborate password. Once word of the flaw leaks, the password can be reverse engineered by anyone, and the legitimate owners are likely to find themselves in a race to move their assets before the thieves do. Even in the software industry, hackers routinely reverse engineer Microsoft’s patches to find the security flaws they fix and then try to exploit them before the patches have been fully installed.

He doesn’t have any good ideas to fix this. I don’t either. Just add it to the pile of blockchain’s many problems.

Zoom Exploit on MacOS

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/08/zoom-exploit-on-macos.html

This vulnerability was reported to Zoom last December:

The exploit works by targeting the installer for the Zoom application, which needs to run with special user permissions in order to install or remove the main Zoom application from a computer. Though the installer requires a user to enter their password on first adding the application to the system, Wardle found that an auto-update function then continually ran in the background with superuser privileges.

When Zoom issued an update, the updater function would install the new package after checking that it had been cryptographically signed by Zoom. But a bug in how the checking method was implemented meant that giving the updater any file with the same name as Zoom’s signing certificate would be enough to pass the test—so an attacker could substitute any kind of malware program and have it be run by the updater with elevated privilege.

It seems that it’s not entirely fixed:

Following responsible disclosure protocols, Wardle informed Zoom about the vulnerability in December of last year. To his frustration, he says an initial fix from Zoom contained another bug that meant the vulnerability was still exploitable in a slightly more roundabout way, so he disclosed this second bug to Zoom and waited eight months before publishing the research.

EDITED TO ADD: Disclosure works. The vulnerability seems to be patched now.

Apple’s Lockdown Mode

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/07/apples-lockdown-mode-2.html

I haven’t written about Apple’s Lockdown Mode yet, mostly because I haven’t delved into the details. This is how Apple describes it:

Lockdown Mode offers an extreme, optional level of security for the very few users who, because of who they are or what they do, may be personally targeted by some of the most sophisticated digital threats, such as those from NSO Group and other private companies developing state-sponsored mercenary spyware. Turning on Lockdown Mode in iOS 16, iPadOS 16, and macOS Ventura further hardens device defenses and strictly limits certain functionalities, sharply reducing the attack surface that potentially could be exploited by highly targeted mercenary spyware.

At launch, Lockdown Mode includes the following protections:

  • Messages: Most message attachment types other than images are blocked. Some features, like link previews, are disabled.
  • Web browsing: Certain complex web technologies, like just-in-time (JIT) JavaScript compilation, are disabled unless the user excludes a trusted site from Lockdown Mode.
  • Apple services: Incoming invitations and service requests, including FaceTime calls, are blocked if the user has not previously sent the initiator a call or request.
  • Wired connections with a computer or accessory are blocked when iPhone is locked.
  • Configuration profiles cannot be installed, and the device cannot enroll into mobile device management (MDM), while Lockdown Mode is turned on.

What Apple has done here is really interesting. It’s common to trade security off for usability, and the results of that are all over Apple’s operating systems—and everywhere else on the Internet. What they’re doing with Lockdown Mode is the reverse: they’re trading usability for security. The result is a user experience with fewer features, but a much smaller attack surface. And they aren’t just removing random features; they’re removing features that are common attack vectors.

There aren’t a lot of people who need Lockdown Mode, but it’s an excellent option for those who do.

News article.

EDITED TO ADD (7/31): An analysis of the effect of Lockdown Mode on Safari.

Critical Vulnerabilities in GPS Trackers

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/07/critical-vulnerabilities-in-gps-trackers.html

This is a dangerous vulnerability:

An assessment from security firm BitSight found six vulnerabilities in the Micodus MV720, a GPS tracker that sells for about $20 and is widely available. The researchers who performed the assessment believe the same critical vulnerabilities are present in other Micodus tracker models. The China-based manufacturer says 1.5 million of its tracking devices are deployed across 420,000 customers. BitSight found the device in use in 169 countries, with customers including governments, militaries, law enforcement agencies, and aerospace, shipping, and manufacturing companies.

BitSight discovered what it said were six “severe” vulnerabilities in the device that allow for a host of possible attacks. One flaw is the use of unencrypted HTTP communications that makes it possible for remote hackers to conduct adversary-in-the-middle attacks that intercept or change requests sent between the mobile application and supporting servers. Other vulnerabilities include a flawed authentication mechanism in the mobile app that can allow attackers to access the hardcoded key for locking down the trackers and the ability to use a custom IP address that makes it possible for hackers to monitor and control all communications to and from the device.

The security firm said it first contacted Micodus in September to notify company officials of the vulnerabilities. BitSight and CISA finally went public with the findings on Tuesday after trying for months to privately engage with the manufacturer. As of the time of writing, all of the vulnerabilities remain unpatched and unmitigated.

These are computers and computer vulnerabilities, but because the computers are attached to cars, the vulnerabilities become potentially life-threatening. CISA writes:

These vulnerabilities could impact access to a vehicle fuel supply, vehicle control, or allow locational surveillance of vehicles in which the device is installed.

I wouldn’t have buried “vehicle control” in the middle of that sentence.

M1 Chip Vulnerability

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/06/m1-chip-vulnerability.html

This is a new vulnerability against Apple’s M1 chip. Researchers say that it is unpatchable.

Researchers from MIT’s Computer Science and Artificial Intelligence Laboratory, however, have created a novel hardware attack, which combines memory corruption and speculative execution attacks to sidestep the security feature. The attack shows that pointer authentication can be defeated without leaving a trace, and as it utilizes a hardware mechanism, no software patch can fix it.

The attack, appropriately called “Pacman,” works by “guessing” a pointer authentication code (PAC), a cryptographic signature that confirms that an app hasn’t been maliciously altered. This is done using speculative execution—a technique used by modern computer processors to speed up performance by speculatively guessing various lines of computation—to leak PAC verification results, while a hardware side-channel reveals whether or not the guess was correct.

What’s more, since there are only so many possible values for the PAC, the researchers found that it’s possible to try them all to find the right one.

It’s not obvious how to exploit this vulnerability in the wild, so I’m unsure how important this is. Also, I don’t know if it also applies to Apple’s new M2 chip.

Research paper. Another news article.

Hacking Tesla’s Remote Key Cards

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/06/hacking-teslas-remote-key-cards.html

Interesting vulnerability in Tesla’s NFC key cards:

Martin Herfurt, a security researcher in Austria, quickly noticed something odd about the new feature: Not only did it allow the car to automatically start within 130 seconds of being unlocked with the NFC card, but it also put the car in a state to accept entirely new keys—with no authentication required and zero indication given by the in-car display.

“The authorization given in the 130-second interval is too general… [it’s] not only for drive,” Herfurt said in an online interview. “This timer has been introduced by Tesla…in order to make the use of the NFC card as a primary means of using the car more convenient. What should happen is that the car can be started and driven without the user having to use the key card a second time. The problem: within the 130-second period, not only the driving of the car is authorized, but also the [enrolling] of a new key.”

Cloudflare observations of Confluence zero day (CVE-2022-26134)

Post Syndicated from Vaibhav Singhal original https://blog.cloudflare.com/cloudflare-observations-of-confluence-zero-day-cve-2022-26134/

Cloudflare observations of Confluence zero day (CVE-2022-26134)

On 2022-06-02 at 20:00 UTC Attlasian released a Security Advisory relating to a remote code execution (RCE) vulnerability affecting Confluence Server and Confluence Data Center products. This post covers our current analysis of this vulnerability.

When we learned about the vulnerability, Cloudflare’s internal teams immediately engaged to ensure all our customers and our own infrastructure were protected:

  • Our Web Application Firewall (WAF) teams started work on our first mitigation rules that were deployed on 2022-06-02 at 23:38 UTC for all customers.
  • Our internal security team started reviewing our Confluence instances to ensure Cloudflare itself was not impacted.

What is the impact of this vulnerability?

According to Volexity, the vulnerability results in full unauthenticated RCE, allowing an attacker to fully take over the target application.

Active exploits of this vulnerability leverage command injections using specially crafted strings to load a malicious class file in memory, allowing attackers to subsequently plant a webshell on the target machine that they can interact with.

Once the vulnerability is exploited, attackers can implant additional malicious code such as Behinder; a custom webshell called noop.jsp, which replaces the legitimate noop.jsp file located at Confluence root>/confluence/noop.jsp; and another open source webshell called Chopper.

Our observations of exploit attempts in the wild

Once we learned of the vulnerability, we began reviewing  our WAF data to identify activity related to exploitation of the vulnerability. We identified requests matching potentially malicious payloads as early as 2022-05-26 00:33 UTC, indicating that knowledge of the exploit was realized by some attackers prior to the Atlassian security advisory.

Since our mitigation rules were put in place, we have seen a large spike in activity starting from 2022-06-03 10:30 UTC — a little more than 10 hours after the new WAF rules were first deployed. This large spike coincides with the increased awareness of the vulnerability and release of public proof of concepts. Attackers are actively scanning for vulnerable applications at time of writing.

Cloudflare observations of Confluence zero day (CVE-2022-26134)

Although we have seen valid attack payloads since 2022-05-26, many payloads that started matching our initial WAF mitigation rules once the advisory was released were not valid against this specific vulnerability. Examples provided below:

Cloudflare observations of Confluence zero day (CVE-2022-26134)

The activity above indicates that actors were using scanning tools to try and identify the attack vectors. Exact knowledge of how to exploit the vulnerability may have been consolidated amongst select attackers and may not have been widespread.

The decline in WAF rule matches in the graph above after 2022-06-03 23:00 UTC is due to us releasing improved WAF rules. The new, updated rules greatly improved accuracy, reducing the number of false positives, such as the examples above.

A valid malicious URL targeting a vulnerable Confluence application is shown below:

Cloudflare observations of Confluence zero day (CVE-2022-26134)

(Where $HOSTNAME is the host of the target application.)

The URL above will run the contents of the HTTP request post body eval(#parameters.data[0]). Normally this will be a script that will download a web shell to the local server allowing the attacker to run arbitrary code on demand.

Other example URLs, omitting the schema and hostname, include:

Cloudflare observations of Confluence zero day (CVE-2022-26134)

Some of the activity we are observing is indicative of malware campaigns and botnet behavior. It is important to note that given the payload structure, other WAF rules have also been effective at mitigating particular variations of the attack. These include rule PHP100011 and PLONE0002.

Cloudflare’s response to CVE-2022-26134

We have a defense-in-depth approach which uses Cloudflare to protect Cloudflare. We had  high confidence that we were not impacted by this vulnerability due to the security measures in place. We confirmed this by leveraging our detection and response capabilities to sweep all of our internal assets and logs for signs of attempted compromise.

The main actions we took in response to this incident were:

  1. Gathered as much information as possible about the attack.
  2. Engaged our WAF team to start working on mitigation rules for this CVE.
  3. Searched our logs for any signs of compromise.
  4. We searched the logs from our internal Confluence instances for any signs of attempted exploits. We supplemented our assessment with the pattern strings provided by Atlasian: “${“.
  5. Any matches were reviewed to find out if they could be actual exploits. We found no signs that our systems were targeted by actual exploits.
  6. As soon as the WAF team was confident of the quality of the new rules, we started deploying them to all our servers to start protecting our customers as soon as possible. As we also use the WAF for our internal systems, our Confluence instances are also protected by the new WAF rules.
  7. We scrutinized our Confluence servers for signs of compromise and the presence of malicious implants. No signs of compromise were detected.
  8. We deployed rules to our SIEM and monitoring systems to detect any new exploitation attempt against our Confluence instances.

How Cloudflare uses Confluence

Cloudflare uses Confluence internally as our main wiki platform. Many of our teams use Confluence as their main knowledge-sharing platform. Our internal instances are protected by Cloudflare Access. In previous blog posts, we described how we use Access to protect internal resources. This means that every request sent to our Confluence servers must be authenticated and validated in accordance with our Access policies. No unauthenticated access is allowed.

This allowed us to be confident that only Cloudflare users are able to submit requests to our Confluence instances, thus reducing the risk of external exploitation attempts.

What to do if you are using Confluence on-prem

If you are an Atlassian customer for their on-prem products, you should patch to their latest fixed versions. We advise the following actions:

  1. Add Cloudflare Access as an extra protection layer for all your websites. Easy-to-follow instructions to enable Cloudflare Access are available here.
  2. Enable a WAF that includes protection for CVE-2022-26134 in front of your Confluence instances. For more information on how to enable Cloudflare’s WAF and other security products, check here.
  3. Check the logs from your Confluence instances for signs of exploitation attempts. Look for the strings /wiki/ and ${ in the same request.
  4. Use forensic tools and check for signs of post-exploitation tools such as webshells or other malicious implants.

Indicators of compromise and attack

The following indicators are associated with activity observed in the wild by Cloudflare, as described above. These indicators can be searched for against logs to determine if there is compromise in the environment associated with the Confluence vulnerability.

Indicators of Compromise (IOC)

# Type Value Filename/Hash
1 File 50f4595d90173fbe8b85bd78a460375d8d5a869f1fef190f72ef993c73534276 Filename: 45.64.json
Malicious file associated with exploit
2 File b85c16a7a0826edbcddbd2c17078472169f8d9ecaa7209a2d3976264eb3da0cc Filename: 45.64.rar
Malicious file associated with exploit
3 File 90e3331f6dd780979d22f5eb339dadde3d9bcf51d8cb6bfdc40c43d147ecdc8c Filename: 45.640.txt
Malicious file associated with exploit
4 File 1905fc63a9490533dc4f854d47c7cb317a5f485218173892eafa31d7864e2043 Filename: 45.647.txt
Malicious file associated with exploit
5 File 5add63588480287d1aee01e8dd267340426df322fe7a33129d588415fd6551fc Filename: lan (perl script)
Malicious file associated with exploit
6 File 67c2bae1d5df19f5f1ac07f76adbb63d5163ec2564c4a8310e78bcb77d25c988 Filename: jui.sh
Malicious file associated with exploit
7 File 281a348223a517c9ca13f34a4454a6fdf835b9cb13d0eb3ce25a76097acbe3fb Filename: conf
Malicious file associated with exploit

Indicators of Attack (IOA)

# Type Value Hash
1 URL String ${ String used to craft malicious payload
2 URL String javax.script.ScriptEngineManager String indicative of ScriptEngine manager to craft malicious payloads

Cloudflare customers are protected from the Atlassian Confluence CVE-2022-26134

Post Syndicated from Reid Tatoris original https://blog.cloudflare.com/cloudflare-customers-are-protected-from-the-atlassian-confluence-cve-2022-26134/

Cloudflare customers are protected from the Atlassian Confluence CVE-2022-26134

Cloudflare customers are protected from the Atlassian Confluence CVE-2022-26134

On June 02, 2022 Atlassian released a security advisory for their Confluence Server and Data Center applications, highlighting a critical severity unauthenticated remote code execution vulnerability. The vulnerability is as CVE-2022-26134 and affects Confluence Server version 7.18.0 and all Confluence Data Center versions >= 7.4.0.

No patch is available yet but Cloudflare customers using either WAF or Access are already protected.

Our own Confluence nodes are protected by both WAF and Access, and at the time of writing, we have found no evidence that our Confluence instance was exploited.

Cloudflare reviewed the security advisory, conducted our own analysis, and prepared a WAF mitigation rule via an emergency release. The rule, once tested, was deployed on June 2, 2022, at 23:38 UTC with a default action of BLOCK and the following IDs:

  • 100531 (for our legacy WAF)
  • 408cff2b  (for our new WAF)

All customers using the Cloudflare WAF to protect their self-hosted Confluence applications have automatically been protected since the new rule was deployed.

Customers who have deployed Cloudflare Access in front of their Confluence applications were protected from external exploitation attempts even before the emergency release. Access verifies every request made to a Confluence application to ensure it is coming from an authenticated user. Any unauthenticated users attempting this exploit would have been blocked by Cloudflare before they could reach the Confluence server.

Customers not yet using zero trust rules to protect access to their applications can follow these instructions to enable Access now in a few minutes.

Timeline of Events

2022-06-02 at 20:00 UTC Atlassian publishes security advisory
2022-06-02 at 23:38 UTC Cloudflare publishes WAF rule to target CVE 2022-26134

When will a patch be available?

Atlassian has not confirmed when a patch will be available, but as noted above, Cloudflare customers protecting their Confluence applications with Cloudflare WAF and Access are protected. We will update this post as soon as new information is available, and we also recommend following the Atlassian security advisory.

Cloudflare’s approach to handling BMC vulnerabilities

Post Syndicated from Derek Chamorro original https://blog.cloudflare.com/bmc-vuln/

Cloudflare’s approach to handling BMC vulnerabilities

Cloudflare’s approach to handling BMC vulnerabilities

In recent years, management interfaces on servers like a Baseboard Management Controller (BMC) have been the target of cyber attacks including ransomware, implants, and disruptive operations. Common BMC vulnerabilities like Pantsdown and USBAnywhere, combined with infrequent firmware updates, have left servers vulnerable.

We were recently informed from a trusted vendor of new, critical vulnerabilities in popular BMC software that we use in our fleet. Below is a summary of what was discovered, how we mitigated the impact, and how we look to prevent these types of vulnerabilities from having an impact on Cloudflare and our customers.


A baseboard management controller is a small, specialized processor used for remote monitoring and management of a host system. This processor has multiple connections to the host system, giving it the ability to monitor hardware, update BIOS firmware, power cycle the host, and many more things.

Cloudflare’s approach to handling BMC vulnerabilities

Access to the BMC can be local or, in some cases, remote. With remote vectors open, there is potential for malware to be installed on the BMC from the local host via PCI Express or the Low Pin Count (LPC) interface. With compromised software on the BMC, malware or spyware could maintain persistence on the server.

Cloudflare’s approach to handling BMC vulnerabilities

According to the National Vulnerability Database, the two BMC chips (ASPEED AST2400 and AST2500) have implemented Advanced High-Performance Bus (AHB) bridges, which allow arbitrary read and write access to the physical address space of the BMC from the host. This means that malware running on the server can also access the RAM of the BMC.

These BMC vulnerabilities are sufficient to enable ransomware propagation, server bricking, and data theft.

Impacted versions

Numerous vulnerabilities were found to affect the QuantaGrid D52B cloud server due to vulnerable software found in the BMC. These vulnerabilities are associated with specific interfaces that are exposed on AST2400 and AST2500 and explained in CVE-2019-6260. The vulnerable interfaces in question are:

  • iLPC2AHB bridge Pt I
  • iLPC2AHB bridge Pt II
  • PCIe VGA P2A bridge
  • DMA from/to arbitrary BMC memory via X-DMA
  • UART-based SoC Debug interface
  • LPC2AHB bridge
  • PCIe BMC P2A bridge
  • Watchdog setup

An attacker might be able to update the BMC directly using SoCFlash through inband LPC or BMC debug universal async receiver-transmitter (UART) serial console. While this might be thought of as a usual path in case of total corruption, this is actually an abuse within SoCFlash by using any open interface for flashing.

Mitigations and response

Updated firmware

We reached out to one of our manufacturers, Quanta, to validate that existing firmware within a subset of systems was in fact patched against these vulnerabilities. While some versions of our firmware were not vulnerable, others were. A patch was released, tested, and deployed on the affected BMCs within our fleet.

Cloudflare Security and Infrastructure teams also proactively worked with additional manufacturers to validate their own BMC patches were not explicitly vulnerable to these firmware vulnerabilities and interfaces.

Reduced exposure of BMC remote interfaces

It is a standard practice within our data centers to implement network segmentation to separate different planes of traffic. Our out-of-band networks are not exposed to the outside world and only accessible within their respective data centers. Access to any management network goes through a defense in depth approach, restricting connectivity to jumphosts and authentication/authorization through our zero trust Cloudflare One service.

Reduced exposure of BMC local interfaces

Applications within a host are limited in what can call out to the BMC. This is done to restrict what can be done from the host to the BMC and allow for secure in-band updating and userspace logging and monitoring.

Do not use default passwords

This sounds like common knowledge for most companies, but we still follow a standard process of changing not just the default username and passwords that come with BMC software, but disabling the default accounts to prevent them from ever being used. Any static accounts follow a regular password rotation.

BMC logging and auditing

We log all activity by default on our BMCs. Logs that are captured include the following:

  • Authentication (Successful, Unsuccessful)
  • Authorization (user/service)
  • Interfaces (SOL, CLI, UI)
  • System status (Power on/off, reboots)
  • System changes (firmware updates, flashing methods)

We were able to validate that there was no malicious activity detected.

What’s next for the BMC

Cloudflare regularly works with several original design manufacturers (ODMs) to produce the highest performing, efficient, and secure computing systems according to our own specifications. The standard processors used for our baseboard management controller often ship with proprietary firmware which is less transparent and more cumbersome to maintain for us and our ODMs. We believe in improving on every component of the systems we operate in over 270 cities around the world.


We are moving forward with OpenBMC, an open-source firmware for our supported baseboard management controllers. Based on the Yocto Project, a toolchain for Linux on embedded systems, OpenBMC will enable us to specify, build, and configure our own firmware based on the latest Linux kernel featureset per our specification, similar to the physical hardware and ODMs.

OpenBMC firmware will enable:

  • Latest stable and patched Linux kernel
  • Internally-managed TLS certificates for secure, trusted communication across our isolated management network
  • Fine-grained credentials management
  • Faster response time for patching and critical updates

While many of these features are community-driven, vulnerabilities like Pantsdown are patched quickly.

Extending secure boot

You may have read about our recent work securing the boot process with a hardware root-of-trust, but the BMC has its own boot process that often starts as soon as the system gets power. Newer versions of the BMC chips we use, as well as leveraging cutting edge security co-processors, will allow us to extend our secure boot capabilities prior to loading our UEFI firmware by validating cryptographic signatures on our BMC/OpenBMC firmware. By extending our security boot chain to the very first device that has power to our systems, we greatly reduce the impact of malicious implants that can be used to take down a server.


While this vulnerability ended up being one we could quickly resolve through firmware updates with Quanta and quick action by our teams to validate and patch our fleet, we are continuing to innovate through OpenBMC, and secure root of trust to ensure that our fleet is as secure as possible. We are grateful to our partners for their quick action and are always glad to report any risks and our mitigations to ensure that you can trust how seriously we take your security.