CVE-2024-9400: Addressing Memory Corruption Vulnerability in Firefox and Thunderbird with JIT Compilation

A recently disclosed vulnerability, CVE-2024-9400, has been found to impact Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131. This vulnerability lies in the potential memory corruption that can be triggered if an attacker has the ability to cause an Out-Of-Memory (OOM) error at a specific time during the Just-In-Time (JIT) compilation process. This blog post aims to provide an in-depth analysis of the vulnerability, its responsible code snippet, and how it can be exploited by attackers.

Background

Before diving into the details of the issue, it is essential to understand what JIT compilation is and its significance in browsers. JIT compilation is the process of converting intermediate code (bytecode) into native machine code at runtime. Many modern browsers, like Firefox and Thunderbird, use JIT compilation to enhance the performance of JavaScript execution. JIT compilation aids in faster loading times for JavaScript heavy web pages, making the overall browsing experience more efficient and seamless.

Vulnerability Details

The vulnerability in question stems from a potential memory corruption in the JIT compilation process. This can be triggered if an attacker can induce an OOM error at a specific moment during the JIT compilation. This error can lead to potential remote code execution scenarios, allowing the attacker to perform arbitrary operations on the affected machine. This negatively affects the security infrastructure and could lead to an unauthorized access of the system.

In the vulnerable code snippet, we can see how JIT compilation is affected by the OOM error

void vulnerable_function() {
  ...
  while (compiling) {
    ...
    if (OOM_triggered) {
      exit(compilation_process); // OOM error causes JIT compilation to terminate
      ...
    }
    ...
  }
  ...
  execute_native_code(); // This function is susceptible to memory corruption
}

The vulnerable function showcases how an OOM error, when induced, can lead the JIT compilation process to terminate prematurely. This premature termination paves the way for memory corruption while executing the native code, thus allowing potential remote code execution.

The following resources provide more information on the vulnerability

1. Mozilla Security Advisory
2. CVE-2024-9400 Details

Exploit

The exploit for this vulnerability would likely involve the attacker crafting malicious JavaScript code that specifically triggers an OOM error during JIT compilation. By successfully inducing such an error, an attacker can cause memory corruption and thereby execute arbitrary code on the target machine. Although the exact exploitation method may vary, the core concept of inducing an OOM error at the right moment remains constant.

Mitigation and Remediation

To address this vulnerability, users are strongly encouraged to update their Firefox and Thunderbird installations to the latest versions, which have resolved the issue:

Thunderbird ESR should be updated to version 128.3 or later

Updating to the latest versions ensures protection from this vulnerability and the potential risk that it carries. It is vital to apply this security update as soon as possible, given the severity of the issue and its implications on system security.

Conclusion

CVE-2024-9400 represents an important vulnerability related to memory corruption that affects Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR. Understanding the details, code snippet responsible, and how the vulnerability can be exploited is essential for users and developers alike. By staying vigilant and keeping software up-to-date, users can safeguard their systems and maintain a secure browsing environment.

Timeline

Published on: 10/01/2024 16:15:11 UTC
Last modified on: 10/04/2024 13:51:25 UTC