CVE-2009-0773 in Firefox
Summary
by MITRE
The JavaScript engine in Mozilla Firefox before 3.0.7, Thunderbird before 2.0.0.21, and SeaMonkey 1.1.15 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via (1) a splice of an array that contains "some non-set elements," which causes jsarray.cpp to pass an incorrect argument to the ResizeSlots function, which triggers memory corruption; (2) vectors related to js_DecompileValueGenerator, jsopcode.cpp, __defineSetter__, and watch, which triggers an assertion failure or a segmentation fault; and (3) vectors related to gczeal, __defineSetter__, and watch, which triggers a hang.
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Analysis
by VulDB Data Team • 08/29/2019
The vulnerability described in CVE-2009-0773 represents a critical security flaw affecting the JavaScript engine components of Mozilla Firefox, Thunderbird, and SeaMonkey browsers. This vulnerability stems from improper handling of array operations and JavaScript engine internals that can lead to both denial of service conditions and potential arbitrary code execution. The flaw specifically targets the jsarray.cpp file where incorrect argument passing to the ResizeSlots function creates memory corruption scenarios that can be exploited by remote attackers. The vulnerability is categorized under CWE-125 as an out-of-bounds read condition and also relates to CWE-122 which covers buffer overflow conditions, making it particularly dangerous for exploitation.
The technical implementation of this vulnerability involves three distinct attack vectors that exploit different aspects of the JavaScript engine's memory management and object handling. The first vector occurs when performing splice operations on arrays containing "non-set elements," which causes jsarray.cpp to pass incorrect parameters to ResizeSlots function, resulting in memory corruption. The second vector involves complex interactions with js_DecompileValueGenerator, jsopcode.cpp, _defineSetter_, and watch functions, leading to assertion failures or segmentation faults that can crash the application. The third vector leverages gczeal, _defineSetter_, and watch functionality to create hanging conditions that effectively cause denial of service. These vectors demonstrate the complexity of JavaScript engine vulnerabilities and their potential for both crash and code execution scenarios.
From an operational impact perspective, this vulnerability poses significant risks to users of affected browser versions as it can be exploited remotely without user interaction. The potential for arbitrary code execution means that attackers could gain full control of affected systems, while the denial of service capabilities can disrupt normal browser operations and potentially be used for more sophisticated attacks. The vulnerability affects a wide range of Mozilla-based applications, making it particularly dangerous as it impacts multiple products in the Mozilla ecosystem. The exploitability characteristics align with ATT&CK technique T1059.007 for JavaScript execution and T1499.004 for network denial of service attacks, demonstrating how this vulnerability can be used in various attack scenarios.
The mitigation strategies for this vulnerability primarily involve immediate software updates to patched versions of Firefox, Thunderbird, and SeaMonkey. Users should upgrade to Firefox 3.0.7, Thunderbird 2.0.0.21, and SeaMonkey 1.1.15 or later versions that contain the necessary fixes. Additionally, system administrators should implement network monitoring to detect potential exploitation attempts and consider temporary network restrictions for vulnerable systems until patches are applied. The vulnerability highlights the importance of regular security updates and proper input validation in JavaScript engines, as well as the need for robust memory management practices in browser components. Organizations should also implement security awareness training to help users recognize potential phishing attempts that might exploit this vulnerability, and maintain comprehensive incident response procedures for handling such security events.