CVE-2012-2799 in FFmpeg
Summary
by MITRE
Unspecified vulnerability in libavcodec/wmalosslessdec.c in FFmpeg before 0.11 has unknown impact and attack vectors, related to the "put bit buffer when num_saved_bits is reset."
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Analysis
by VulDB Data Team • 12/13/2021
The vulnerability identified as CVE-2012-2799 resides within the FFmpeg multimedia framework's libavcodec library, specifically in the wmalosslessdec.c component responsible for decoding WMA Lossless audio streams. This issue affects FFmpeg versions prior to 0.11 and represents a critical security flaw that could potentially be exploited by malicious actors to compromise systems processing multimedia content. The vulnerability manifests in the handling of bit buffer operations during the decoding process, particularly when the num_saved_bits variable undergoes reset operations. The unspecified nature of the impact and attack vectors suggests that this flaw could enable various forms of exploitation depending on the specific conditions under which it is triggered.
The technical root cause of this vulnerability stems from improper handling of bit buffer state management within the WMA Lossless decoder implementation. When the num_saved_bits counter is reset during the decoding process, the system fails to properly account for the state of the bit buffer, creating potential conditions for buffer overflows, memory corruption, or other exploitable conditions. This flaw falls under the category of improper handling of data structures and memory management, which aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read vulnerabilities. The specific implementation issue occurs in the context of bitstream parsing where the decoder attempts to manage bit-level data operations while simultaneously resetting internal counters, creating a race condition or state inconsistency that can be leveraged for exploitation.
The operational impact of this vulnerability extends beyond simple multimedia processing failures, as it represents a potential vector for remote code execution when FFmpeg is used in applications that process untrusted audio content. Systems that utilize FFmpeg for streaming services, media processing pipelines, or multimedia applications become vulnerable to attacks that could result in arbitrary code execution, denial of service, or information disclosure. The attack surface is particularly broad given FFmpeg's widespread adoption across various platforms and applications, including web browsers, media players, content management systems, and server-side multimedia processing applications. This vulnerability can be triggered through crafted WMA Lossless audio files that, when processed by vulnerable FFmpeg versions, cause the decoder to enter an exploitable state during bit buffer management operations.
Mitigation strategies for CVE-2012-2799 primarily focus on upgrading to FFmpeg version 0.11 or later, which includes the necessary patches to address the bit buffer management issue. Organizations should also implement strict input validation for multimedia content, particularly when processing untrusted files, and consider implementing sandboxing or containerization techniques to limit the potential impact of successful exploitation attempts. Network-based mitigations can include content filtering to prevent the processing of suspicious multimedia files, while application-level protections should enforce proper error handling and input sanitization. The vulnerability's classification under ATT&CK technique T1203, which covers Exploitation for Client Execution, indicates that exploitation could occur through malicious multimedia files delivered via email attachments, web downloads, or streaming services, making comprehensive network security measures essential for protection against this threat.