CVE-2024-1556 is a notable security vulnerability affecting Mozilla Firefox versions prior to 123. This flaw occurs due to an incorrect object check for NULL in the built-in profiler, which potentially leads to invalid memory access and undefined behavior. It is essential to note that this issue only affects Firefox when the profiler is running.

In this post, we will discuss the technical details of this vulnerability, its potential impact, and the steps necessary to mitigate its risks. We will also share a code snippet directly related to the bug and provide references to the original vulnerability disclosure and related materials.

Technical Details

At the root of this vulnerability is an error in Firefox's built-in profiler, which is used to analyze the performance of the browser and its associated web content. When the profiler is running, it is supposed to safely access objects in memory by checking for their NULL status. However, an incorrect object is checked for NULL, which leads to accessing invalid memory and triggering undefined behavior.

The following code snippet highlights the problem (in a simplified representation)

/* incorrect NULL check for 'b' instead of 'a' */
void process_object(Object *a, Object *b) {
  if (b == NULL) {
    /* safe operations */
  } else {
    /* potentially unsafe, accessing 'a' without checking for NULL */
    a->do_something();
  }
}

As shown in the snippet above, the NULL check is performed on object 'b' rather than object 'a'. Consequently, the function assumes it's safe to access 'a', potentially leading to invalid memory access and undefined behavior.

Exploit Details

While no known exploits target this vulnerability specifically, a potential attacker may attempt to craft a related exploit exploiting the invalid memory access or undefined behavior resulting from the incorrect NULL check. The exploitation could lead to crashes, information leaks, or even remote code execution, depending on the vulnerability's circumstances.

Mitigation Steps

It is highly recommended that users of Firefox immediately update to version 123 or newer. This update addresses the CVE-2024-1556 vulnerability and prevents the issues associated with the incorrect NULL check. For users who cannot update Firefox to the latest version, they should avoid running the profiler until a newer version can be installed.

Click "Help" and select "About Firefox."

3. The update process should start automatically, and the browser will prompt for a restart upon completion.

- Mozilla Foundation Security Advisory 2024-34
- NIST National Vulnerability Database Listing
- Mozilla Firefox 123 Release Notes

Conclusion

In summary, the CVE-2024-1556 vulnerability is a critical issue affecting Mozilla Firefox versions prior to 123. This flaw results from an incorrect object check for NULL in the built-in profiler, leading to invalid memory access and undefined behavior. Users should update their browser to the latest version as soon as possible to mitigate the risks associated with this vulnerability. So, stay vigilant and keep your software up to date to ensure a safe browsing experience.

Timeline

Published on: 02/20/2024 14:15:09 UTC
Last modified on: 02/20/2024 19:50:53 UTC