CVE-2020-22017 in FFmpeg
Summary
by MITRE • 05/28/2021
A heap-based Buffer Overflow vulnerability exists in FFmpeg 4.2 at ff_fill_rectangle in libavfilter/drawutils.c, which might lead to memory corruption and other potential consequences.
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Analysis
by VulDB Data Team • 05/30/2021
The heap-based buffer overflow vulnerability identified as CVE-2020-22017 represents a critical security flaw within the FFmpeg multimedia framework version 4.2. This vulnerability resides in the ff_fill_rectangle function located within the libavfilter/drawutils.c source file, making it a fundamental component of the video processing pipeline that handles graphical operations and filter rendering. The flaw manifests when the application processes certain video filter operations that involve drawing rectangles on video frames, creating conditions where insufficient bounds checking allows malicious actors to overwrite adjacent heap memory regions. Such vulnerabilities are particularly dangerous in multimedia processing applications due to the extensive memory manipulation required for video frame operations and the complex data structures involved in filter chain processing.
The technical exploitation of this buffer overflow occurs when FFmpeg processes video filters that utilize the ff_fill_rectangle function to render graphical elements or apply visual effects to video content. During normal operation, the function expects specific parameters defining rectangle dimensions and memory allocation boundaries, but when these parameters are manipulated through crafted input files or filter configurations, the function fails to validate buffer boundaries properly. This validation failure results in heap memory corruption where attacker-controlled data can overwrite adjacent memory locations, potentially leading to arbitrary code execution or application crashes. The vulnerability is classified as a heap-based buffer overflow under CWE-122, which specifically addresses insufficient restriction of operations within the bounds of a memory buffer, and represents a direct violation of memory safety principles in C/C++ programming.
The operational impact of CVE-2020-22017 extends beyond simple application instability, presenting significant risks to systems that rely on FFmpeg for video processing, streaming, or media conversion tasks. Attackers could exploit this vulnerability by crafting malicious video files or filter chains that trigger the vulnerable code path, potentially leading to remote code execution on systems running vulnerable FFmpeg versions. This threat is particularly concerning given FFmpeg's widespread adoption across various platforms including web browsers, media servers, content management systems, and mobile applications. The vulnerability's exploitation could result in complete system compromise, data exfiltration, or service denial, making it a high-priority target for threat actors. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for command and scripting interpreter, as exploitation could enable attackers to execute arbitrary code through the corrupted memory state. Additionally, the vulnerability affects the T1557.001 technique related to dynamic resolution, since attackers might leverage the memory corruption to manipulate program execution flow and achieve privilege escalation.
Mitigation strategies for CVE-2020-22017 primarily focus on immediate version updates to FFmpeg 4.3 or later, where the buffer overflow has been addressed through proper bounds checking and memory validation in the ff_fill_rectangle function. System administrators should implement comprehensive patch management protocols to ensure all FFmpeg installations are updated promptly, particularly in environments processing untrusted video content. Additional defensive measures include implementing strict input validation for all media files processed through FFmpeg, utilizing sandboxing techniques to limit potential impact of exploitation, and deploying intrusion detection systems to monitor for suspicious filter chain patterns. Organizations should also consider implementing application whitelisting policies that restrict FFmpeg execution to trusted environments and regularly audit media processing workflows for potential attack vectors. The vulnerability highlights the importance of maintaining up-to-date multimedia libraries and implementing robust security controls around media processing pipelines, as these components often serve as attack surfaces for sophisticated exploitation techniques.