CVE-2013-7020 in FFmpeg
Summary
by MITRE
The read_header function in libavcodec/ffv1dec.c in FFmpeg before 2.1 does not properly enforce certain bit-count and colorspace constraints, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted FFV1 data.
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Analysis
by VulDB Data Team • 01/11/2022
The vulnerability identified as CVE-2013-7020 resides within the FFmpeg multimedia framework's FFV1 video decoder implementation, specifically in the read_header function located in libavcodec/ffv1dec.c. This flaw represents a critical security issue affecting FFmpeg versions prior to 2.1, where the decoder fails to properly validate bit-count and colorspace parameters during the processing of FFV1 encoded video streams. The FFV1 codec is a lossless video compression format developed by the FFmpeg project itself, commonly used in professional video workflows and archival systems where data integrity is paramount.
The technical nature of this vulnerability stems from insufficient input validation within the read_header function, which processes the header information of FFV1 video files. When encountering crafted malicious FFV1 data, the function does not adequately enforce constraints on bit-depth specifications and color space parameters, leading to potential out-of-bounds memory access conditions. This improper validation allows attackers to manipulate the bit-count and colorspace values in ways that exceed the allocated memory boundaries, creating opportunities for memory corruption that can manifest as denial of service conditions or potentially more severe arbitrary code execution scenarios. The vulnerability operates at the decoding layer where the software processes incoming video data streams, making it particularly dangerous for applications that automatically decode media files without proper sanitization.
The operational impact of CVE-2013-7020 extends across numerous applications and systems that rely on FFmpeg for video processing, including media servers, content management systems, digital asset management platforms, and various multimedia applications. Attackers can exploit this vulnerability by crafting malicious FFV1 video files that, when processed by vulnerable FFmpeg implementations, trigger the out-of-bounds array access conditions. This can result in service disruption through application crashes or hangs, effectively creating a denial of service condition that impacts availability. The potential for unspecified other impacts suggests that under certain circumstances, the vulnerability might also enable more sophisticated attacks such as information disclosure or privilege escalation, though these remain theoretical without additional exploitation vectors. The vulnerability is particularly concerning because FFV1 is widely used in professional and broadcast environments where reliability and security are critical requirements.
Organizations should implement immediate mitigation strategies including upgrading to FFmpeg version 2.1 or later where this vulnerability has been addressed through proper input validation and bounds checking. System administrators should also consider implementing additional security controls such as input sanitization layers, file type validation, and content filtering mechanisms that can detect and block suspicious FFV1 data before it reaches the vulnerable decoder. The vulnerability aligns with CWE-129, which describes improper validation of array index values, and may map to ATT&CK technique T1059.007 for execution through multimedia processing. Regular security assessments and vulnerability scanning should include checks for FFmpeg installations to ensure they are running patched versions, as this vulnerability could be exploited in automated attack scenarios targeting media processing systems and web applications that handle user-uploaded video content.