CVE-2016-7785 in FFmpeg
Summary
by MITRE
The avi_read_seek function in libavformat/avidec.c in FFmpeg before 3.1.4 allows remote attackers to cause a denial of service (assert fault) via a crafted AVI file.
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Analysis
by VulDB Data Team • 07/15/2019
The vulnerability identified as CVE-2016-7785 represents a critical denial of service flaw within the FFmpeg multimedia framework, specifically affecting the avi_read_seek function in the libavformat/avidec.c component. This issue exists in FFmpeg versions prior to 3.1.4 and enables remote attackers to trigger an assertion failure through the careful crafting of AVI media files. The flaw demonstrates a fundamental weakness in input validation and error handling mechanisms within the video processing library that powers numerous applications and systems worldwide. Such vulnerabilities are particularly dangerous as they can be exploited across various platforms and applications that rely on FFmpeg for media handling operations.
The technical implementation of this vulnerability stems from insufficient boundary checking and validation within the avi_read_seek function, which processes seek operations for AVI format files. When a maliciously crafted AVI file is processed by FFmpeg, the function fails to properly validate the seek parameters, leading to an assertion fault that causes the application to crash or become unresponsive. This type of flaw falls under CWE-129, which describes improper validation of array index values, and represents a classic example of how inadequate input sanitization can lead to system instability. The assertion failure occurs during the file parsing phase when the library attempts to handle seek operations on malformed AVI structures, demonstrating a lack of robust error handling in the media processing pipeline.
The operational impact of CVE-2016-7785 extends beyond simple denial of service, as it can be leveraged to disrupt services in applications that utilize FFmpeg for media processing. Systems running vulnerable versions of FFmpeg, including web servers, media streaming platforms, and content management systems, become susceptible to exploitation by attackers who can craft malicious AVI files to crash these services. This vulnerability is particularly concerning in environments where automated media processing occurs, as it can be exploited to create sustained denial of service conditions that may be difficult to detect and mitigate. The flaw can be categorized under ATT&CK technique T1499.004, which involves network denial of service attacks, and represents a significant threat to service availability in multimedia processing environments.
Mitigation strategies for this vulnerability require immediate patching of FFmpeg installations to version 3.1.4 or later, where the issue has been resolved through improved input validation and error handling mechanisms. System administrators should also implement additional protective measures such as input sanitization for media files, rate limiting for media processing requests, and monitoring for unusual processing patterns that might indicate exploitation attempts. Organizations using FFmpeg in production environments should conduct thorough vulnerability assessments to identify all systems running vulnerable versions and implement automated patch management processes. The fix implemented in version 3.1.4 demonstrates the importance of proper boundary checking and input validation in multimedia processing libraries, aligning with industry best practices for secure coding and defensive programming techniques.