CVE-2011-2161 in FFmpeg
Summary
by MITRE
The ape_read_header function in ape.c in libavformat in FFmpeg before 0.5.4, as used in MPlayer, VideoLAN VLC media player, and other products, allows remote attackers to cause a denial of service (application crash) via an APE (aka Monkey s Audio) file that contains a header but no frames.
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Analysis
by VulDB Data Team • 11/07/2021
The vulnerability described in CVE-2011-2161 represents a classic buffer over-read condition that affects multimedia processing libraries handling APE audio files. This flaw exists within the ape_read_header function in the libavformat component of FFmpeg, which serves as a foundational library for numerous media playback applications including MPlayer and VLC media player. The vulnerability specifically targets the parsing logic for Monkey's Audio files, a lossless audio compression format that has gained popularity in the audio community for its efficient compression ratios and high fidelity output.
The technical nature of this vulnerability stems from improper validation of audio file structures during the header parsing phase. When an APE file contains a valid header but lacks actual audio frames, the ape_read_header function fails to properly handle this edge case, leading to memory access violations that result in application crashes. This behavior manifests as a denial of service condition where legitimate media playback operations are interrupted by the application terminating unexpectedly. The flaw demonstrates a clear lack of input sanitization and boundary checking in the audio file format parser, which is a common pattern seen in multimedia library vulnerabilities.
From an operational perspective, this vulnerability poses significant risk to end-user systems as it can be exploited through simple malicious APE files delivered via email attachments, web downloads, or file sharing networks. The impact extends beyond individual user inconvenience to potential security implications in environments where automated media processing or streaming services are deployed. Attackers can craft specially formatted APE files that will cause any vulnerable application to crash upon attempting to parse them, effectively creating a reliable denial of service vector that can be used to disrupt media playback services or potentially as part of larger attack campaigns targeting media-centric applications.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and can be mapped to ATT&CK technique T1499.004 for denial of service through resource exhaustion or application crashes. Organizations utilizing affected software should prioritize immediate patching of their media playback systems, particularly those that process untrusted media content from external sources. Recommended mitigations include implementing strict file format validation, deploying network-based intrusion detection systems that can identify suspicious media file patterns, and establishing secure media handling policies that restrict automatic playback of unverified content. The fix typically involves adding proper boundary checks and error handling within the audio file parsing logic to ensure that applications gracefully handle malformed or incomplete audio files without crashing.