CVE-2011-1931 in VLC Media Player
Summary
by MITRE
sp5xdec.c in the Sunplus SP5X JPEG decoder in libavcodec in FFmpeg before 0.6.3 and libav through 0.6.2, as used in VideoLAN VLC media player 1.1.9 and earlier and other products, performs a write operation outside the bounds of an unspecified array, which allows remote attackers to cause a denial of service (memory corruption) or possibly execute arbitrary code via a malformed AMV file.
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Analysis
by VulDB Data Team • 11/14/2021
The vulnerability identified as CVE-2011-1931 represents a critical buffer overflow condition within the Sunplus SP5X JPEG decoder implementation in FFmpeg's libavcodec library. This flaw exists in the sp5xdec.c file where an unspecified array is accessed beyond its allocated boundaries during the processing of AMV (Audio Moving Video) file format content. The vulnerability affects multiple versions of FFmpeg prior to 0.6.3 and libav through 0.6.2, making it particularly dangerous as it impacts widely deployed media processing software including VideoLAN VLC media player version 1.1.9 and earlier. The issue stems from inadequate input validation and boundary checking during JPEG decompression operations, creating a scenario where malformed input data can trigger unexpected memory access patterns.
The technical exploitation of this vulnerability occurs when a maliciously crafted AMV file is processed by vulnerable software applications. During the JPEG decoding process, the SP5X decoder fails to properly validate array indices or buffer limits, allowing a write operation to occur outside the legitimate memory boundaries of an internal array structure. This memory corruption can manifest in two primary ways: either causing a denial of service through application crashes or potentially enabling arbitrary code execution if the corrupted memory locations can be manipulated to redirect program execution flow. The vulnerability's classification as a buffer overflow aligns with CWE-121, which specifically addresses stack-based buffer overflow conditions, and potentially CWE-125, which covers out-of-bounds read/write operations. From an operational perspective, this vulnerability presents a significant risk to multimedia applications that process untrusted content, as attackers can remotely trigger system instability or potentially gain unauthorized code execution privileges.
The impact of this vulnerability extends beyond individual application crashes to encompass broader security implications for systems processing multimedia content. When exploited, the vulnerability can compromise the integrity of the affected software's memory management, potentially allowing attackers to execute malicious code with the privileges of the running application. This risk is particularly elevated in media player environments where users frequently encounter untrusted content from various sources. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and code execution techniques, as the memory corruption can be leveraged to bypass security controls. Organizations using affected software versions face potential exposure to remote exploitation scenarios where attackers can craft malicious AMV files to compromise systems. The vulnerability's presence in both FFmpeg and libav libraries means that any software product relying on these components for media processing is at risk, including but not limited to media players, content management systems, and streaming platforms that handle multimedia files from untrusted sources.
Mitigation strategies for CVE-2011-1931 primarily focus on immediate software updates and patches to address the underlying buffer overflow condition. System administrators should prioritize upgrading to FFmpeg versions 0.6.3 or later and libav versions 0.6.3 or later, which contain the necessary fixes for the sp5xdec.c buffer overflow issue. Additionally, implementing proper input validation and sanitization measures within applications that process multimedia content can provide additional defense-in-depth protection. Network administrators should consider implementing content filtering mechanisms to prevent the processing of untrusted AMV files, while application developers should ensure proper boundary checking and array validation in their media processing libraries. The vulnerability's remediation also involves updating affected software products such as VideoLAN VLC media player to versions that incorporate the patched FFmpeg libraries, ensuring comprehensive protection against this specific memory corruption exploit.