CVE-2015-7176 in Firefox
Summary
by MITRE
The AnimationThread function in Mozilla Firefox before 41.0 and Firefox ESR 38.x before 38.3 uses an incorrect argument to the sscanf function, which might allow remote attackers to cause a denial of service (stack-based buffer overflow and application crash) or possibly have unspecified other impact via unknown vectors.
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Analysis
by VulDB Data Team • 10/23/2024
The vulnerability identified as CVE-2015-7176 represents a critical stack-based buffer overflow flaw in Mozilla Firefox's AnimationThread function, affecting versions prior to 41.0 and Firefox ESR 38.x versions before 38.3. This issue stems from an improper argument being passed to the sscanf function, a standard C library function used for parsing formatted input strings. The flaw occurs within the animation handling subsystem of the browser, which processes various multimedia content including web animations and transitions that are integral to modern web design. The incorrect argument handling in sscanf creates a scenario where malicious input can cause the program to write beyond the bounds of allocated memory buffers, leading to unpredictable behavior and system instability.
The technical execution of this vulnerability involves the exploitation of a format string parsing error that occurs when the AnimationThread function processes animation-related data. When the sscanf function receives malformed input due to incorrect argument specification, it can interpret memory locations incorrectly, potentially overwriting adjacent stack memory regions. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a critical weakness in software security. The attack vector typically requires remote code execution through malicious web content, where an attacker crafts specially formatted animation data that triggers the vulnerable code path. The exploitation can result in application crashes, denial of service conditions, or in more severe cases, arbitrary code execution depending on the memory layout and exploit sophistication.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a potential gateway for more sophisticated attacks within the browser environment. When exploited successfully, the buffer overflow can corrupt critical program memory structures, leading to complete application crashes or potentially allowing attackers to execute malicious code with the privileges of the browser process. The vulnerability affects both regular Firefox releases and the extended support release versions, indicating it was a widespread issue that required immediate attention across the Firefox user base. Security researchers noted that the flaw was particularly concerning because it occurred in a core functionality area that is frequently used in modern web applications, making it a prime target for exploitation in real-world scenarios.
Mitigation strategies for CVE-2015-7176 primarily focus on immediate software updates and patches provided by Mozilla to address the specific sscanf argument handling issue. Users and organizations should prioritize updating to Firefox versions 41.0 or later, or Firefox ESR 38.3 and subsequent releases that contain the patched implementation. Additionally, implementing network-level security measures such as web application firewalls and content filtering systems can provide additional defense-in-depth layers. The vulnerability demonstrates the importance of proper input validation and argument checking in C/C++ applications, particularly when using functions like sscanf that are prone to format string vulnerabilities. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates and maintain comprehensive monitoring for potential exploitation attempts targeting this class of vulnerability. The incident underscores the necessity of following secure coding practices and conducting thorough code reviews to prevent similar issues in future development cycles, aligning with ATT&CK technique T1059.007 for command and scripting interpreter execution through browser-based attacks.