Google Chrome, the world’s most popular web browser, sometimes has security issues just like any complex software. One particularly noteworthy vulnerability—CVE-2022-4191—was found in Chrome’s Sign-In functionality. In this post, let’s break down what this bug is, how it works, see some proof-of-concept code, and show where you can learn more.

What Is CVE-2022-4191?

CVE-2022-4191 is a "use after free" vulnerability. That means Chrome tried to use a piece of memory after it was already deleted (“freed”) by the program. If an attacker can trick the browser into running code at the right time—like while you’re logging in—it can cause Chrome to misbehave, or worse, let hackers run their own code.

Specifically, this bug existed before Chrome version 108..5359.71. Google says a remote attacker could convince a user to interact with the UI (such as clicking something during sign-in), then potentially achieve “heap corruption” by exploiting how user profiles are destroyed in memory.

This is a medium severity issue because, while attackers need user interaction, it can still lead to browser crashes or even code execution in some scenarios.

References

- Official Chromium Security Bug Report
- NIST NVD CVE Entry

Let’s look at a simple analogy: Suppose you have a list of tasks

1. Take out the trash
2. Delete the list
3. Read the second item on the list

If you delete your list at step 2, but try to read from it in step 3, that’s a clear mistake. In code, this can sometimes be dangerous, especially if a hacker can control what’s in that list after deletion.

In Chrome’s case: The sign-in process deleted (“destroyed”) an internal user profile object, but due to a bug, Chrome still tried to use it afterward. If an attacker can carefully time the process, they might insert malicious data in memory (the “heap”), causing Chrome to misbehave or run arbitrary code.

Proof-of-Concept Code Snippet

Chrome is huge and complex, but let’s see a simplified version of how a use-after-free could look in C++:

class UserProfile {
public:
    void destroyProfile() {
        delete this;
    }

    void signIn() {
        // Vulnerable: signIn might be called after destroyProfile
        printf("Signing in user!\n");
        // ...sign-in logic...
    }
};

void simulateExploit() {
    UserProfile* profile = new UserProfile();
    profile->destroyProfile(); // Deletes the object

    // Attack: Call method on deleted object
    profile->signIn(); // Use-after-free!!
}

In real Chrome code, the attacker would need to trigger deletion and then force Chrome to access the destroyed object, possibly through a crafted website or a malicious extension.

How Did Attackers Exploit It?

The original bug required convincing you to interact with Chrome’s UI in a certain way during sign-in. For example, an attacker could:

Trigger sign-in and profile destruction at the same time in a crafted way

If successful, the heap corruption might allow the attacker to crash your browser or, with additional trickery, execute code. Fortunately, no active exploitation was reported before the patch.

Am I Still At Risk?

If you’re using Chrome 108..5359.71 or later—you’re safe!  
Google patched this issue quickly in November 2022. For the best security, always keep your browser up-to-date.

Detailed References

- Chromium Security Release Note - Nov 29, 2022
- NIST National Vulnerability Database: CVE-2022-4191
- A Closer Look at Use-after-free Bugs in Chrome (Google Project Zero)

Conclusion

CVE-2022-4191 is a classic reminder that even giants like Chrome can have memory bugs—which is why regular updates matter. This use-after-free in Sign-In let remote attackers potentially corrupt memory or execute code, but only with user interaction. Thankfully, Google patched it quickly. Always update your browser, and be careful with suspicious websites and extension requests!


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Timeline

Published on: 11/30/2022 00:15:00 UTC
Last modified on: 05/03/2023 12:16:00 UTC