CVE-2011-4031 in FFmpeg
Summary
by MITRE
Integer underflow in the asfrtp_parse_packet function in libavformat/rtpdec_asf.c in FFmpeg before 0.8.3 allows remote attackers to execute arbitrary code via a crafted ASF packet.
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Analysis
by VulDB Data Team • 12/01/2021
The vulnerability identified as CVE-2011-4031 represents a critical integer underflow flaw within the FFmpeg multimedia framework's RTP (Real-time Transport Protocol) decoder component. This vulnerability specifically affects the asfrtp_parse_packet function located in the libavformat/rtpdec_asf.c source file, which handles the parsing of ASF (Advanced Systems Format) packets within RTP streams. The flaw exists in FFmpeg versions prior to 0.8.3, making it a significant security concern for systems that process multimedia content through RTP protocols.
The technical nature of this vulnerability stems from improper input validation within the packet parsing logic where an integer underflow occurs when processing specially crafted ASF packets. An integer underflow happens when a calculation results in a value that wraps around to a much smaller number than expected, often causing memory access violations or buffer overflows. In this case, the underflow allows attackers to manipulate the size calculations used for memory allocation or buffer boundaries, creating opportunities for arbitrary code execution. The vulnerability is particularly dangerous because it can be triggered through network-based attacks without requiring user interaction, making it a remote code execution vulnerability.
The operational impact of CVE-2011-4031 extends across various multimedia applications and systems that utilize FFmpeg for processing RTP streams containing ASF content. This includes media servers, streaming platforms, video conferencing systems, and any application that accepts RTP input and processes ASF packets through FFmpeg's libraries. Attackers can exploit this vulnerability by crafting malicious ASF packets that, when processed by vulnerable FFmpeg implementations, trigger the integer underflow condition. The resulting memory corruption can lead to complete system compromise, allowing attackers to execute arbitrary code with the privileges of the affected application. This makes the vulnerability particularly attractive to threat actors targeting multimedia processing infrastructure.
The vulnerability aligns with CWE-191, which specifically addresses integer underflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could lead to arbitrary code execution. Organizations using vulnerable FFmpeg versions face significant risk, particularly in environments where RTP streams are processed without proper input sanitization. The vulnerability's exploitability is enhanced by the widespread use of FFmpeg across multimedia applications and the relatively simple nature of crafting malicious ASF packets. Mitigation strategies should prioritize immediate patching of FFmpeg to version 0.8.3 or later, along with network-based filtering to prevent suspicious RTP traffic from reaching systems processing multimedia content, and implementation of proper input validation measures for all multimedia processing pipelines.
This vulnerability highlights the importance of proper integer handling in multimedia processing libraries and demonstrates how seemingly minor flaws in protocol parsing can lead to severe security consequences. The integer underflow in the RTP decoder represents a classic example of how buffer boundary calculations can be manipulated through crafted inputs, emphasizing the need for comprehensive input validation and robust error handling in multimedia frameworks. Organizations should also consider implementing network segmentation and monitoring for unusual RTP traffic patterns as additional defensive measures against similar vulnerabilities that may exist in other multimedia processing components.