CVE-2011-4353 in Libav
Summary
by MITRE
The (1) av_image_fill_pointers, (2) vp5_parse_coeff, and (3) vp6_parse_coeff functions in FFmpeg 0.5.x before 0.5.7, 0.6.x before 0.6.4, 0.7.x before 0.7.9, and 0.8.x before 0.8.8; and in Libav 0.5.x before 0.5.6, 0.6.x before 0.6.4, and 0.7.x before 0.7.3 allow remote attackers to cause a denial of service (out-of-bounds read) via a crafted VP5 or VP6 stream.
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Analysis
by VulDB Data Team • 12/12/2021
The vulnerability described in CVE-2011-4353 represents a critical out-of-bounds read flaw affecting multimedia processing libraries that handle VP5 and VP6 video codecs. This issue impacts FFmpeg versions prior to 0.5.7, 0.6.4, 0.7.9, and 0.8.8, as well as Libav versions before their respective patch releases. The vulnerability manifests through three specific functions: av_image_fill_pointers, vp5_parse_coeff, and vp6_parse_coeff, which are fundamental components in the decoding and processing of video streams. These functions are particularly susceptible to malformed input data that can cause memory access violations when processing crafted VP5 or VP6 streams, creating a significant risk for systems that rely on these libraries for multimedia processing.
The technical nature of this vulnerability stems from inadequate bounds checking within the VP5 and VP6 codec parsers. When processing maliciously crafted video streams, the functions fail to validate the size and structure of coefficient data, leading to memory access patterns that extend beyond allocated buffer boundaries. This flaw operates at the intersection of buffer management and codec parsing, where insufficient input validation allows attackers to manipulate memory access pointers. The vulnerability specifically affects the coefficient parsing mechanisms used in these video codecs, where the parser does not properly verify the length of coefficient data or the boundaries of internal data structures before attempting to read or write values. This type of flaw falls under CWE-129, which addresses improper validation of array indices, and represents a classic example of how insufficient bounds checking can lead to memory corruption vulnerabilities.
The operational impact of CVE-2011-4353 extends beyond simple denial of service, as it creates potential pathways for more sophisticated attacks within multimedia processing environments. Remote attackers can leverage this vulnerability to cause applications using affected libraries to crash, resulting in service disruption and potential system instability. In environments where multimedia processing is critical, such as content delivery networks, video streaming platforms, or media processing servers, this vulnerability could be exploited to create persistent service interruptions. The attack vector requires only the delivery of a crafted VP5 or VP6 stream to the target system, making it particularly dangerous as it can be triggered through normal media playback scenarios. The vulnerability's impact is amplified by the widespread use of FFmpeg and Libav libraries across various software applications, including browsers, media players, and content management systems, creating a broad attack surface.
Mitigation strategies for CVE-2011-4353 primarily focus on immediate software updates and patches to affected versions of FFmpeg and Libav libraries. System administrators should prioritize upgrading to patched versions that include proper bounds checking in the affected functions, with particular attention to the vp5_parse_coeff and vp6_parse_coeff implementations. Additional protective measures include implementing input validation at the application level, where applications consuming these libraries can add additional checks before processing potentially malicious media streams. Network-level filtering approaches can also be employed to prevent the delivery of known malicious VP5 or VP6 streams to vulnerable systems, though this approach is less reliable due to the difficulty of accurately identifying malicious content. Organizations should also consider implementing sandboxing mechanisms for multimedia processing components and monitoring for unusual memory access patterns that might indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1203, which covers "Exploitation for Client Execution," suggests that defensive measures should include both endpoint protection and network monitoring capabilities to detect and prevent exploitation attempts.