CVE-2020-22015 in FFmpeg
Summary
by MITRE • 05/26/2021
Buffer Overflow vulnerability in FFmpeg 4.2 in mov_write_video_tag due to the out of bounds in libavformat/movenc.c, which could let a remote malicious user obtain sensitive information, cause a Denial of Service, or execute arbitrary code.
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Analysis
by VulDB Data Team • 05/29/2021
The vulnerability CVE-2020-22015 represents a critical buffer overflow flaw within FFmpeg version 4.2 that resides in the mov_write_video_tag function of the movenc.c file within the libavformat library. This issue stems from an out-of-bounds memory access condition that occurs during the processing of video media files, specifically when handling MOV format containers. The flaw manifests when FFmpeg attempts to write video tags to media files, creating an opportunity for attackers to exploit the improper bounds checking mechanisms that fail to validate the size of data being written to allocated memory buffers.
The technical exploitation of this vulnerability occurs through carefully crafted malicious media files that trigger the buffer overflow condition during the encoding or transcoding process. When FFmpeg processes such malformed input files, the mov_write_video_tag function fails to properly validate the length of video data being written, leading to memory corruption that can be leveraged for multiple attack vectors. The vulnerability's classification as a buffer overflow aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. This type of flaw enables attackers to manipulate program execution flow and potentially gain unauthorized access to system resources.
From an operational impact perspective, this vulnerability presents significant security risks to systems that utilize FFmpeg for media processing tasks, particularly in environments where users can upload or process external media files. Remote attackers can exploit this flaw by crafting specially designed video files that, when processed by vulnerable FFmpeg installations, can trigger denial of service conditions or arbitrary code execution. The potential for remote code execution makes this vulnerability particularly dangerous in web applications, content management systems, or media processing services that automatically transcode user-uploaded videos. The vulnerability affects not only direct FFmpeg usage but also applications that depend on FFmpeg libraries, creating a wide attack surface across various media processing platforms.
The exploitation of CVE-2020-22015 aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to initial access through malicious file delivery and privilege escalation via code execution. Attackers can leverage this vulnerability to establish persistent access to systems by executing malicious code within the context of FFmpeg processes. The vulnerability's impact extends beyond immediate exploitation to include potential information disclosure, where attackers might be able to read sensitive data from memory locations that have been corrupted through the buffer overflow. This type of information leakage could expose system credentials, application data, or other sensitive information stored in memory. Organizations using FFmpeg for media processing should prioritize patching this vulnerability as it represents a significant risk to their security posture.
Mitigation strategies for this vulnerability primarily focus on updating FFmpeg installations to versions that contain the appropriate fixes for the buffer overflow condition. The vulnerability was addressed in FFmpeg version 4.3 and later releases, making patch management a critical security control for affected organizations. Additionally, input validation and sanitization should be implemented at application layers that utilize FFmpeg to process user-uploaded media files, including limiting file size, validating file formats, and implementing proper error handling. Network segmentation and access controls can help limit the potential impact of exploitation by restricting access to systems that process media files. Organizations should also consider implementing runtime monitoring and anomaly detection systems that can identify suspicious behavior associated with media processing activities. The vulnerability's nature makes it particularly important to conduct regular security assessments of media processing pipelines and ensure that all dependencies are kept current with security patches.