CVE-2012-0823 in libvpx
Summary
by MITRE
VP8 Codec SDK (libvpx) before 1.0.0 "Duclair" allows remote attackers to cause a denial of service (application crash) via (1) unspecified "corrupt input" or (2) by "starting decoding from a P-frame," which triggers an out-of-bounds read, related to "the clamping of motion vectors in SPLITMV blocks".
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Analysis
by VulDB Data Team • 11/30/2021
The CVE-2012-0823 vulnerability affects the VP8 Codec SDK library version prior to 1.0.0, specifically impacting applications that utilize the libvpx library for video decoding operations. This vulnerability represents a critical security flaw that can be exploited by remote attackers to cause application crashes and denial of service conditions. The vulnerability is particularly concerning as it affects a widely used video codec library that powers numerous multimedia applications, web browsers, and streaming platforms. The issue stems from improper handling of malformed video data during the decoding process, specifically when processing VP8 encoded video streams.
The technical flaw manifests in two distinct attack vectors that exploit different aspects of the VP8 decoding algorithm. The first vector involves corrupt input data that can cause the decoder to crash when processing malformed video frames, while the second vector specifically targets P-frame decoding operations that trigger out-of-bounds memory reads. The core issue lies in the improper clamping of motion vectors within SPLITMV blocks, which are used in VP8 video compression to represent motion compensation data. When the decoder encounters malformed motion vector data during P-frame processing, it attempts to access memory locations outside the allocated buffer boundaries, resulting in memory corruption and application termination. This vulnerability maps to CWE-125 Out-of-bounds Read and CWE-787 Out-of-bounds Write, both of which are classified as critical memory safety issues in the Common Weakness Enumeration catalog. The attack pattern aligns with ATT&CK technique T1499.004 Network Denial of Service, as it enables remote adversaries to disrupt service availability through application crashes.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be leveraged in more sophisticated attacks targeting multimedia applications, web browsers, and streaming services. Applications that rely on libvpx for VP8 video decoding, including popular browsers like Chrome and Firefox, media players, and video conferencing software, are at risk of being exploited. The vulnerability is particularly dangerous in web environments where users may unknowingly encounter maliciously crafted video content, making it a prime target for drive-by download attacks and web-based exploitation campaigns. Attackers can craft specially designed VP8 video files that trigger the out-of-bounds read condition when processed by vulnerable applications, leading to complete application crashes and potential system instability. The vulnerability's remote exploitability means that no local access is required, and the attack can be executed through web browsers or media players without user interaction beyond visiting a malicious website or opening a compromised file.
Mitigation strategies for CVE-2012-0823 should prioritize immediate software updates and patches from vendors who utilize the affected libvpx library. System administrators should ensure that all applications using libvpx are updated to version 1.0.0 or later, which includes fixes for the motion vector clamping issue. Additionally, network administrators can implement content filtering measures to block or scan VP8 video content from untrusted sources. The vulnerability highlights the importance of input validation and memory safety practices in multimedia codec implementations, emphasizing the need for robust error handling and bounds checking in video processing libraries. Organizations should also consider implementing sandboxing techniques for multimedia processing to limit the potential impact of similar vulnerabilities in the future. Security monitoring should include detection of unusual application crashes or memory access patterns that might indicate exploitation attempts, as this vulnerability can be used in combination with other exploits to achieve more sophisticated attack objectives.