CVE-2009-2477 in Firefox
Summary
by MITRE
js/src/jstracer.cpp in the Just-in-time (JIT) JavaScript compiler (aka TraceMonkey) in Mozilla Firefox 3.5 before 3.5.1 allows remote attackers to execute arbitrary code via certain use of the escape function that triggers access to uninitialized memory locations, as originally demonstrated by a document containing P and FONT elements.
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Analysis
by VulDB Data Team • 12/07/2024
The vulnerability identified as CVE-2009-2477 represents a critical memory safety issue within the TraceMonkey JIT compiler component of Mozilla Firefox 3.5 before version 3.5.1. This flaw exists in the js/src/jstracer.cpp file and specifically targets the JavaScript engine's optimization mechanisms that are designed to improve performance by compiling frequently executed code paths into machine code. The vulnerability arises from improper handling of memory allocation during JIT compilation processes, creating conditions where uninitialized memory segments could be accessed and potentially exploited by malicious actors.
The technical exploitation of this vulnerability occurs through specific patterns involving the JavaScript escape function within the context of HTML document parsing. When Firefox processes documents containing P and FONT elements, the JIT compiler's trace recording mechanism encounters a scenario where memory locations are not properly initialized before being accessed. This creates a situation where the compiler may execute code from memory locations that contain arbitrary data, leading to potential code execution. The vulnerability is classified under CWE-457 as "Use of Uninitialized Variable" and can be mapped to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript' within the execution phase of an attack chain.
The operational impact of this vulnerability is severe as it allows remote attackers to execute arbitrary code on affected systems without requiring any user interaction beyond visiting a malicious webpage. The attack vector leverages the browser's legitimate JavaScript processing capabilities to create a memory access violation that can be manipulated to redirect program execution flow. This makes the vulnerability particularly dangerous in web-based attack scenarios where users might inadvertently encounter malicious content. The flaw affects not just the specific version mentioned but potentially other configurations where similar JIT compilation patterns are present, making it a widespread concern for web browser security.
Mitigation strategies for this vulnerability require immediate patching of affected Firefox installations to version 3.5.1 or later, which contains the necessary fixes to prevent the uninitialized memory access patterns. System administrators should implement network-level protections such as web application firewalls and content filtering systems to block known malicious content. Additionally, browser hardening measures including disabling unnecessary JavaScript features, implementing strict content security policies, and using sandboxing mechanisms can reduce the attack surface. Organizations should also consider deploying intrusion detection systems to monitor for exploitation attempts and maintain up-to-date threat intelligence feeds to identify related attack patterns. The fix implemented in the patched version addresses the root cause by ensuring proper initialization of memory locations before JIT compilation processes access them, thereby preventing the exploitation of uninitialized memory segments that could otherwise be manipulated for code execution purposes.