CVE-2012-2795 in FFmpeg
Summary
by MITRE
Multiple unspecified vulnerabilities in libavcodec/wmalosslessdec.c in FFmpeg before 0.11 have unknown impact and attack vectors related to (1) size of "mclms arrays," (2) "a get_bits(0) in decode_ac_filter," and (3) "too many bits in decode_channel_residues()."
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Analysis
by VulDB Data Team • 12/13/2021
The vulnerability identified as CVE-2012-2795 resides within the FFmpeg multimedia framework's libavcodec library, specifically in the wmalosslessdec.c component responsible for decoding Windows Media Audio Lossless format. This flaw affects FFmpeg versions prior to 0.11 and represents a collection of three distinct but related issues that collectively weaken the system's robustness against malformed input data. The vulnerability is classified under CWE-129 as an Improper Validation of Array Index, indicating that the system fails to properly validate array boundaries during the decoding process. The security implications extend beyond simple memory corruption, as these issues could potentially enable remote code execution or denial of service attacks when maliciously crafted audio files are processed by vulnerable applications.
The technical implementation of these vulnerabilities manifests through three primary attack vectors that exploit different aspects of the decoding algorithm. The first issue involves the improper handling of "mclms arrays" where the size validation mechanism fails to properly constrain array allocations, potentially leading to buffer overflows when processing specially crafted audio data. The second vulnerability occurs in the decode_ac_filter function where a get_bits(0) operation is executed, creating a potential for integer underflow or other bit manipulation errors that could corrupt memory structures. The third vulnerability arises in decode_channel_residues() where the system processes "too many bits," indicating that the bitstream parsing logic does not adequately validate the number of bits consumed during decoding operations. These issues are particularly dangerous because they occur during the core decoding process where input validation should be most rigorous.
The operational impact of CVE-2012-2795 extends across numerous applications that rely on FFmpeg for multimedia processing, including media players, content management systems, and streaming platforms. When exploited, these vulnerabilities could allow attackers to execute arbitrary code on systems processing affected media files, potentially leading to complete system compromise. The attack vectors remain unspecified in the original description, suggesting that the vulnerabilities could be triggered through various means including email attachments, web downloads, or streaming content. This lack of specificity makes the vulnerability particularly concerning for security professionals as it implies multiple potential attack surfaces. The vulnerability directly relates to ATT&CK technique T1203 by enabling process injection through memory corruption, and T1059 through potential command execution in compromised systems.
Mitigation strategies for CVE-2012-2795 require immediate patching of all affected FFmpeg installations to version 0.11 or later, where the vulnerabilities have been addressed through improved input validation and boundary checking mechanisms. Organizations should also implement strict input validation policies for all multimedia content, particularly when processing user-uploaded files or content from untrusted sources. Network-level defenses should include content filtering and sandboxing of multimedia processing components to limit the potential impact of exploitation attempts. Security monitoring should focus on detecting unusual memory access patterns or decoding failures that might indicate exploitation attempts. The remediation process should also include comprehensive testing of all applications that utilize FFmpeg to ensure that the patched version functions correctly without introducing regressions in multimedia processing capabilities. Additionally, organizations should consider implementing application whitelisting policies to prevent execution of untrusted multimedia processing applications that might be vulnerable to similar issues.