CVE-2012-6616 in FFmpeg
Summary
by MITRE
The mov_text_decode_frame function in libavcodec/movtextdec.c in FFmpeg before 1.0.2 allows remote attackers to cause a denial of service (out-of-bounds read and crash) via crafted 3GPP TS 26.245 data.
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Analysis
by VulDB Data Team • 01/18/2022
The vulnerability identified as CVE-2012-6616 represents a critical out-of-bounds read flaw within the FFmpeg multimedia framework's handling of 3GPP TS 26.245 subtitle data. This issue affects versions prior to 1.0.2 and specifically targets the mov_text_decode_frame function located in libavcodec/movtextdec.c. The vulnerability arises when FFmpeg processes malformed or specially crafted 3GPP TS 26.245 formatted subtitle streams, which are commonly used in mobile video content and streaming applications. The flaw allows remote attackers to construct malicious subtitle data that, when processed by the affected FFmpeg version, triggers memory access violations leading to application crashes and potential denial of service conditions.
The technical implementation of this vulnerability stems from inadequate input validation within the subtitle decoding logic. When FFmpeg encounters 3GPP TS 26.245 data, the mov_text_decode_frame function fails to properly bounds-check array accesses or validate the structure of the incoming data before attempting to parse and render subtitle information. This lack of proper validation creates a scenario where crafted data can cause the decoder to read memory locations beyond the allocated buffer boundaries, resulting in unpredictable behavior including segmentation faults, application termination, and system instability. The vulnerability operates at the decoding layer of multimedia processing, making it particularly dangerous as it can be triggered simply by playing content containing malicious subtitle streams without requiring any special user interaction or privilege escalation.
From an operational perspective, this vulnerability presents significant risks to multimedia applications and services that rely on FFmpeg for video processing and playback. The denial of service impact means that any system processing 3GPP TS 26.245 formatted content could be rendered unavailable, affecting streaming services, media players, and content delivery networks. The remote exploitability aspect makes this vulnerability particularly concerning for web-based applications and services that process user-uploaded media content, as attackers could craft malicious files to disrupt service availability. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and represents a classic example of how insufficient input validation can lead to memory corruption issues that can be leveraged for denial of service attacks.
The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for "Network Denial of Service" and potentially T1059.007 for "Command and Scripting Interpreter: PowerShell" if exploited through automated systems. Organizations using FFmpeg for multimedia processing should implement immediate mitigations including upgrading to version 1.0.2 or later, implementing input validation controls for 3GPP TS 26.245 data, and deploying network monitoring to detect unusual processing patterns that might indicate exploitation attempts. Additionally, security teams should consider implementing sandboxing mechanisms for multimedia processing and establishing robust patch management procedures to ensure timely deployment of security updates. The vulnerability underscores the importance of maintaining up-to-date multimedia libraries and implementing defense-in-depth strategies for processing untrusted media content in enterprise environments.