CVE-2012-2775 in FFmpeg
Summary
by MITRE
Unspecified vulnerability in the read_var_block_data function in libavcodec/alsdec.c in FFmpeg before 0.11, and Libav 0.7.x before 0.7.7 and 0.8.x before 0.8.4, has unknown impact and attack vectors, related to a large order and an "out of array write in quant_cof."
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Analysis
by VulDB Data Team • 12/13/2021
The vulnerability identified as CVE-2012-2775 represents a critical memory corruption issue affecting multimedia processing libraries within the FFmpeg and Libav ecosystems. This flaw resides in the read_var_block_data function located within libavcodec/alsdec.c, specifically impacting versions prior to FFmpeg 0.11 and Libav 0.7.7 and 0.8.4. The vulnerability manifests through a combination of large order processing and improper array boundary checking, creating a scenario where quant_cof array operations can exceed allocated memory boundaries. The unspecified nature of the impact and attack vectors suggests that this vulnerability could potentially enable arbitrary code execution or system instability depending on how the affected libraries are utilized in various applications.
The technical implementation of this vulnerability stems from inadequate input validation within the audio lossless decoding process. When processing certain audio data streams, particularly those involving large order parameters, the read_var_block_data function fails to properly validate array access boundaries before writing to the quant_cof array. This condition creates a classic out-of-bounds write vulnerability that can be exploited by malicious actors to overwrite adjacent memory locations. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, though the specific memory corruption pattern suggests more complex exploitation possibilities. The flaw demonstrates poor defensive programming practices where input parameters are not adequately constrained against maliciously crafted data sequences that could trigger the out-of-bounds memory access.
The operational impact of CVE-2012-2775 extends across numerous applications that rely on FFmpeg or Libav for multimedia processing, including media players, content management systems, and streaming services. Attackers could potentially exploit this vulnerability by crafting specially formatted audio files that, when processed by vulnerable applications, trigger the memory corruption. This could lead to denial of service conditions, application crashes, or in more sophisticated attack scenarios, arbitrary code execution on systems running vulnerable software. The vulnerability's presence in widely-used multimedia libraries means that exploitation could affect a broad range of endpoints from desktop applications to server-side media processing systems. The attack surface is particularly concerning given that many applications automatically process user-uploaded media content without proper sanitization, making this vulnerability a potential vector for remote code execution in affected environments.
Mitigation strategies for CVE-2012-2775 primarily focus on immediate software updates and patches to the affected libraries. Organizations should prioritize upgrading to FFmpeg 0.11 or later versions and Libav 0.7.7/0.8.4 or later releases where the vulnerability has been addressed through proper input validation and array boundary checking. Additionally, implementing input sanitization measures at application layers can provide defense-in-depth protection, particularly for legacy systems that cannot be immediately updated. Network-based protections such as content filtering and media validation can help prevent exploitation of this vulnerability in environments where updated software is not immediately available. Security monitoring should include detection of unusual memory access patterns and potential exploitation attempts in systems processing multimedia content, with particular attention to audio file processing activities that might trigger the vulnerable code path. The remediation process should also include comprehensive vulnerability assessments of systems that utilize these libraries to identify any potential exposure to similar memory corruption vulnerabilities within the broader multimedia processing stack.