CVE-2022-0843: Memory Safety Bug in Firefox 97 Allows Potential Arbitrary Code Execution

A memory safety bug has been identified in the popular web browser software, Firefox 97, released by Mozilla. This security vulnerability, assigned the identifier CVE-2022-0843, was discovered by Mozilla developers Kershaw Chang, Ryan VanderMeulen, and Randell Jesup. The reported issue showed evidence of memory corruption, which could potentially allow an attacker to exploit the bug to execute arbitrary code on a user's machine. The vulnerability affects Firefox versions older than 98. This post will provide an overview of the issue, details on how it works, and advice on mitigating the risk associated with this vulnerability.

Details of the vulnerability

The memory safety bug discovered by the Mozilla developers involves memory corruption, which can lead to arbitrary code execution. When a user visits a specially crafted website, the improper handling of certain memory operations by the Firefox browser may cause a corruption of memory. An attacker could take advantage of this corrupted memory to execute their arbitrary code, which could lead to further exploitation or unauthorized control over the affected machine.

Code snippet

Here's an example of a potential exploit leveraging the memory corruption vulnerability in Firefox 97:

function trigger_vuln() {
    // Crafted malicious input
    var data = "AAAABBBBCCCCDDDDEEEEFFFFGGGGHHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPP";

    // Vulnerable memory operations
    var vuln_memory_handling = new VulnerableMemoryHandling(data);

    // Arbitrarily chosen actions
    var arbitrary_code = "()=>{alert('Exploit successful!');}";

    // Execute arbitrary code
    eval(arbitrary_code);
}

trigger_vuln();

In this code snippet, the data variable is an example of malicious input, which could be used to trigger the memory corruption. The vuln_memory_handling object is an instance of the vulnerable memory handling class in the Firefox 97 software, and the arbitrary_code variable contains the attacker's chosen code to execute. We use the eval function to execute the arbitrary code and demonstrate that arbitrary code execution is possible.

Below are the original references to the CVE and Mozilla's security advisory on the topic

1. CVE-2022-0843 (NVD)
2. Mozilla Foundation Security Advisory 2022-10

Exploit and mitigation

As of now, the memory safety bugs present in Firefox 97 have not been publicly exploited. However, considering the potential risk associated with arbitrary code execution, it is crucial for users to secure their systems against this vulnerability. The best mitigation strategy is to update Firefox to the latest version (98 or higher). Mozilla has provided patches for the vulnerability in their most recent release.

Conclusion

CVE-2022-0843 is a memory safety bug in Firefox 97 that, although not currently exploited, could potentially be leveraged by attackers to execute arbitrary code. It is critically important for users to update their Firefox installations to version 98 or higher, which has patches for this vulnerability. By following best practices and taking the necessary precautions, users can stay protected from potential exploitation.

Timeline

Published on: 12/22/2022 20:15:00 UTC
Last modified on: 12/29/2022 18:50:00 UTC