CVE-2011-3951 in FFmpeg
Summary
by MITRE
The dpcm_decode_frame function in dpcm.c in libavcodec in FFmpeg before 0.10 and in Libav 0.5.x before 0.5.9, 0.6.x before 0.6.6, 0.7.x before 0.7.6, and 0.8.x before 0.8.1 allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via a crafted stereo stream in a media file.
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Analysis
by VulDB Data Team • 12/08/2021
The vulnerability identified as CVE-2011-3951 represents a critical security flaw within the FFmpeg multimedia framework's audio decoding capabilities. This issue affects the dpcm_decode_frame function in the dpcm.c file, which handles decoding of delta pulse code modulation audio streams. The vulnerability manifests when processing specially crafted stereo audio streams that exploit memory handling errors during the decoding process. The affected versions span across multiple releases of both FFmpeg and its fork Libav, indicating a widespread impact within the multimedia processing ecosystem. This flaw constitutes a remote code execution vulnerability that can be triggered through malicious media files, making it particularly dangerous for applications that process untrusted audio content.
The technical exploitation of this vulnerability stems from improper bounds checking and memory management within the delta pulse code modulation decoding routine. When the dpcm_decode_frame function encounters a malformed stereo stream, it fails to properly validate input parameters before attempting to allocate memory or perform arithmetic operations. This leads to buffer overflows, memory corruption, and ultimately application crashes that can be leveraged to execute arbitrary code. The vulnerability operates at the codec level where the decoder processes audio data without adequate input sanitization, creating a pathway for attackers to manipulate the decoding process through crafted media files. The issue is classified under CWE-125 as an out-of-bounds read, which aligns with the memory corruption patterns observed in this vulnerability.
The operational impact of CVE-2011-3951 extends beyond simple denial of service scenarios to encompass potential remote code execution capabilities that can be exploited by attackers. Systems utilizing FFmpeg or Libav for media processing, including web servers, media streaming platforms, content management systems, and multimedia applications, become vulnerable to this attack vector. The vulnerability can be triggered through various attack vectors including web browsing, email attachments, or file sharing scenarios where users download and process media files. The exploitability of this vulnerability is particularly concerning given that many applications automatically process media content without proper user intervention or content validation, creating an automated attack surface. This vulnerability directly maps to ATT&CK technique T1203, which involves exploiting software vulnerabilities to gain code execution capabilities.
Mitigation strategies for CVE-2011-3951 require immediate software updates to patched versions of FFmpeg and Libav. Organizations should prioritize updating their multimedia processing systems to versions that include the security fixes implemented by the respective development teams. The patches typically address the memory handling issues by implementing proper bounds checking, input validation, and buffer management within the dpcm_decode_frame function. Additionally, implementing content filtering mechanisms that scan media files for known malicious patterns or employing sandboxing techniques can provide additional defense layers. Network administrators should consider implementing network-based intrusion detection systems that can identify and block suspicious media file transfers. Organizations should also conduct thorough vulnerability assessments to identify systems that may be running affected versions of the software and ensure that all multimedia processing components are regularly updated to maintain security posture against similar vulnerabilities.