CVE-2024-29943: Out-of-Bounds Read/Write Exploit on a JavaScript Object in Firefox < 124..1

Security researchers have discovered a critical vulnerability in the popular web browser Firefox. Dubbed CVE-2024-29943, this exploit allows potential cybercriminals to perform an out-of-bounds read or write on a JavaScript object. This vulnerability can compromise user data and expose sensitive information. Mozilla, the organization behind Firefox, has acknowledged the issue and released a patch, advising Firefox users to update the browser to version 124..1 or higher immediately.

Technical Details

The crux of the vulnerability lies in the range-based bounds check elimination process. Attackers can trick this check into allowing out-of-bounds read or write operations on a JavaScript object. To exploit this vulnerability, the attacker injects a malicious JavaScript code, leading to unpredictable browser behavior and security hazards.

Here's an code snippet showcasing the vulnerability

function maliciousFunction(arr) {
  let len = arr.length;
  let idx = len * 2; // Tricking the range-based check to allow out-of-bounds access
  arr[idx] = 'malicious_value'; // Writing the malicious value to an out-of-bounds index
}
document.onreadystatechange = function () {
  if (document.readyState === 'interactive') {
    let safeArray = [1, 2, 3, 4, 5];
    maliciousFunction(safeArray);
    // safeArray now contains potentially dangerous out-of-bounds data
  }
}

In this example, the array 'safeArray' should contain only the original values, but the attacker manages to write a malicious value to an out-of-bounds index. For a real-life scenario, the attacker could leverage this exploit to exfiltrate sensitive user data or compromise the entire browser application. Keep in mind that this is just an example; attack scenarios and code will differ based on the attacker's motive and available exploits.

References

1. Original Mozilla Advisory: https://www.mozilla.org/en-US/security/advisories/mfsa2024-25
This is Mozilla's official security advisory page, containing detailed information about the CVE-2024-29943 vulnerability, alongside the fixes and patches.

2. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-29943
MITRE Corporation's CVE page offers an extensive knowledge base on the vulnerability, including its description, assigned CVSS scores, and impact.

3. Mozilla Firefox Download Page: https://www.mozilla.org/en-US/firefox/new/
If you are running an older version of Firefox, immediately download and install the latest patched version of Firefox from the official download page.

Mitigation Steps

Users running versions of Firefox below 124..1 should immediately update to the latest version to prevent any potential exploits. Strictly scrutinizing the JavaScript code executed on a web page is another important preventive measure. Regularly updating all software, including your web browser, is a generally recommended security practice.

In Conclusion

It's crucial to stay informed about vulnerabilities like CVE-2024-29943 to address security threats and defend against cyberattacks. Users must remain vigilant and keep their software updated to the latest versions to maintain robust security and protect themselves effectively.

Timeline

Published on: 03/22/2024 13:15:07 UTC
Last modified on: 08/12/2024 17:35:03 UTC