CVE-2012-0859 in FFmpeg
Summary
by MITRE
The render_line function in the vorbis codec (vorbis.c) in libavcodec in FFmpeg before 0.9.1 allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via a crafted Vorbis file, related to a large multiplier. NOTE: this vulnerability exists because of an incomplete fix for CVE-2011-3893.
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Analysis
by VulDB Data Team • 03/25/2021
The vulnerability identified as CVE-2012-0859 represents a critical security flaw in the FFmpeg multimedia framework's handling of Vorbis audio codecs. This issue specifically targets the render_line function within the vorbis.c file of libavcodec, which is part of the broader FFmpeg codebase used extensively across various media processing applications and systems. The vulnerability emerged as an incomplete remediation for a previously addressed flaw, CVE-2011-3893, demonstrating how security patches can sometimes introduce new attack vectors when not thoroughly validated. The flaw resides in the way the Vorbis codec processes audio data, creating a scenario where maliciously crafted audio files can trigger unexpected behavior in the decoding process.
The technical implementation of this vulnerability exploits a large multiplier condition within the render_line function that causes integer overflow or arithmetic errors when processing specially crafted Vorbis audio files. When the affected FFmpeg version encounters such malformed audio data, the multiplication operation within the codec's decoding logic results in values that exceed the expected data type limits, leading to unpredictable memory behavior. This condition can manifest as either a denial of service through application crashes or potentially more severe outcomes including arbitrary code execution on the target system. The vulnerability's exploitation requires an attacker to craft a specific Vorbis file that triggers the problematic multiplication sequence, making it a targeted attack vector rather than a widespread vulnerability.
The operational impact of CVE-2012-0859 extends beyond simple service disruption to potentially enable remote code execution in affected systems, making it particularly dangerous for applications that process untrusted media content. Systems utilizing FFmpeg for audio processing, streaming services, media servers, and content management platforms become vulnerable to this attack vector. The vulnerability's presence in libavcodec means that any application relying on this library for audio decoding is at risk, including web browsers, media players, streaming applications, and server-side media processing systems. The incomplete fix for CVE-2011-3893 suggests that the security team's initial response to address the previous vulnerability may have overlooked certain edge cases in the multiplication logic, leaving a backdoor for exploitation.
Mitigation strategies for CVE-2012-0859 require immediate system updates to FFmpeg versions 0.9.1 or later, where the vulnerability has been properly addressed through comprehensive code reviews and testing. Organizations should implement robust input validation and sanitization measures for all media files processed through FFmpeg-based systems, particularly when handling untrusted content from external sources. Security teams should also consider deploying network-based intrusion detection systems that can identify and block suspicious Vorbis file patterns, while implementing application-level sandboxing to limit the potential damage from successful exploitation attempts. This vulnerability aligns with CWE-191, Integer Underflow/Overflow, and maps to ATT&CK techniques involving code injection and privilege escalation through software vulnerabilities, emphasizing the importance of maintaining up-to-date multimedia processing libraries and conducting regular security assessments of media handling components within applications.