CVE-2009-2664 in Firefox
Summary
by MITRE
The js_watch_set function in js/src/jsdbgapi.cpp in the JavaScript engine in Mozilla Firefox before 3.0.12 allows remote attackers to cause a denial of service (assertion failure and application exit) or possibly execute arbitrary code via a crafted .js file, related to a "memory safety bug." NOTE: this was originally reported as affecting versions before 3.0.13.
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Analysis
by VulDB Data Team • 08/13/2021
The vulnerability described in CVE-2009-2664 represents a critical memory safety issue within the JavaScript engine of Mozilla Firefox, specifically affecting versions prior to 3.0.12. This flaw exists within the js_watch_set function located in js/src/jsdbgapi.cpp, which is part of the JavaScript debugging API implementation. The vulnerability stems from inadequate input validation and memory management practices that allow malicious actors to manipulate the JavaScript engine's behavior through carefully crafted javascript files. The issue manifests as an assertion failure that can lead to application termination or potentially more severe consequences including arbitrary code execution.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write operations. These classifications indicate that the flaw involves improper handling of memory boundaries within the JavaScript engine's debugging functionality. The js_watch_set function appears to fail to properly validate input parameters when processing watch expressions, allowing attackers to trigger memory corruption through malformed javascript code. This type of vulnerability falls under the ATT&CK technique T1059.007 for JavaScript and T1203 for Exploitation for Client Execution, as it enables remote code execution through web-based attack vectors.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially enable remote code execution on affected systems. When a user visits a malicious website or opens a specially crafted javascript file, the vulnerable Firefox version will process the malicious code and trigger the assertion failure. This can result in the application crashing and terminating, or in more severe cases, the attacker may be able to leverage the memory corruption to execute arbitrary code with the privileges of the browser process. The vulnerability is particularly dangerous because it can be exploited through web content without requiring user interaction beyond visiting a malicious site, making it a prime target for drive-by download attacks.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Firefox versions to 3.0.12 or later, which contains the necessary fixes for the memory safety issues. Organizations should also implement network-level protections such as web application firewalls and content filtering solutions that can detect and block malicious javascript content. Browser security hardening measures including disabling javascript for untrusted sites, implementing sandboxing technologies, and using security extensions can provide additional defense-in-depth layers. The fix implemented by Mozilla likely involved proper bounds checking and memory validation within the js_watch_set function to prevent the assertion failures and memory corruption that enabled the exploit. Security monitoring should include detection of unusual javascript execution patterns and application crashes that may indicate exploitation attempts.