CVE-2011-3945 in FFmpeg
Summary
by MITRE
The decode_frame function in the KVG1 decoder (kgv1dec.c) in libavcodec in FFmpeg 0.7.x before 0.7.12 and 0.8.x before 0.8.11, and in Libav 0.5.x before 0.5.9, 0.6.x before 0.6.6, 0.7.x before 0.7.5, and 0.8.x before 0.8.1, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted media file.
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Analysis
by VulDB Data Team • 12/12/2021
The vulnerability identified as CVE-2011-3945 represents a critical buffer overflow condition within the KVG1 decoder implementation in FFmpeg and Libav multimedia processing libraries. This flaw exists in the decode_frame function located in kgv1dec.c, affecting multiple versions of both FFmpeg and Libav across their 0.7.x, 0.8.x, and 0.5.x to 0.8.x release lines. The vulnerability stems from inadequate input validation and memory management within the video decoding process, specifically when handling malformed KVG1 format media files. The issue manifests as a classic stack-based buffer overflow that occurs during frame decoding operations, where attacker-controlled data can overwrite adjacent memory locations.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with CWE-121 Stack-based Buffer Overflow, where insufficient bounds checking allows attackers to write beyond allocated buffer boundaries. When a maliciously crafted media file is processed by the affected software, the decode_frame function fails to properly validate the size parameters of incoming frame data, leading to memory corruption. This corruption can result in immediate program termination through segmentation faults or more insidiously, allow for arbitrary code execution if the overflowed memory regions can be manipulated to control program execution flow. The vulnerability's impact extends beyond simple denial of service, as the memory corruption can potentially be leveraged to inject and execute malicious code within the context of the affected application.
The operational impact of CVE-2011-3945 is significant across multiple threat scenarios and attack vectors that align with ATT&CK techniques such as T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution. Systems utilizing affected versions of FFmpeg or Libav for media processing, including web servers, content management systems, media streaming platforms, and digital asset management solutions, face substantial risk of both service disruption and potential system compromise. The vulnerability's remote exploitability means that attackers can trigger the condition through web-based media playback, file sharing systems, or any application that processes user-uploaded media content without proper sanitization. The crash conditions can be reliably reproduced through specific media file construction, making this vulnerability particularly dangerous for automated exploitation frameworks and malicious actors seeking to disrupt services or establish persistent access.
Mitigation strategies for CVE-2011-3945 must address both immediate remediation and long-term security posture improvements. The primary and most effective mitigation involves upgrading to patched versions of FFmpeg (0.7.12+, 0.8.11+) or Libav (0.5.9+, 0.6.6+, 0.7.5+, 0.8.1+), which include proper input validation and bounds checking mechanisms. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly, particularly in environments where media processing occurs. Additional protective measures include deploying input validation filters that sanitize media file headers and content before processing, implementing network segmentation to limit exposure, and utilizing sandboxing techniques to contain potential exploitation attempts. Security monitoring should include detection of anomalous media processing patterns and unauthorized file uploads that could indicate exploitation attempts, with intrusion detection systems configured to identify potential buffer overflow signatures. The vulnerability's characteristics make it particularly suitable for detection through behavioral analysis rather than signature-based approaches, as the memory corruption patterns can vary based on system architecture and implementation details.