CVE-2017-14055 in FFmpeg
Summary
by MITRE
In libavformat/mvdec.c in FFmpeg 3.3.3, a DoS in mv_read_header() due to lack of an EOF (End of File) check might cause huge CPU and memory consumption. When a crafted MV file, which claims a large "nb_frames" field in the header but does not contain sufficient backing data, is provided, the loop over the frames would consume huge CPU and memory resources, since there is no EOF check inside the loop.
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Analysis
by VulDB Data Team • 12/27/2022
The vulnerability identified as CVE-2017-14055 represents a critical denial of service weakness within the FFmpeg multimedia framework, specifically affecting version 3.3.3. This flaw resides in the mvdec.c file within the libavformat component, which handles various multimedia file formats including the MV format used for video content. The issue manifests when processing specially crafted MV files that contain malformed headers with inflated frame count values. The vulnerability stems from the absence of proper end-of-file validation mechanisms within the mv_read_header() function, creating a scenario where the parser enters an unbounded loop iteration based on the deceptive frame count parameter.
The technical implementation of this vulnerability exploits the lack of input validation and boundary checking within the multimedia parsing logic. When FFmpeg encounters an MV file with an inflated "nb_frames" field in its header structure, the parser proceeds to iterate through what it believes to be a large number of frames, typically in the range of millions or billions. However, since the actual file data contains insufficient backing information to support this claimed frame count, the parser continues consuming CPU cycles and memory resources without encountering a proper termination condition. This behavior directly maps to CWE-129, which addresses improper validation of array indices and buffer overflows, and CWE-772, concerning missing resource cleanup, as the system fails to properly manage memory allocation and processing resources during the malformed input parsing.
The operational impact of this vulnerability extends beyond simple resource exhaustion, presenting significant security implications for systems processing multimedia content. Attackers can leverage this weakness by crafting malicious MV files that trigger the problematic code path, leading to substantial CPU utilization and memory consumption that can effectively瘫痪 systems or cause denial of service conditions. This vulnerability is particularly concerning in server environments where FFmpeg is used for media processing, transcoding, or streaming services, as it can be exploited to disrupt legitimate operations and potentially cause cascading failures in multimedia processing pipelines. The attack vector requires minimal sophistication as it only requires the creation of a malformed file, making it an attractive target for automated exploitation campaigns.
Mitigation strategies for CVE-2017-14055 should focus on implementing proper input validation and resource management within the affected FFmpeg components. The most effective approach involves updating to FFmpeg version 3.3.4 or later, where the vulnerability has been patched through the addition of proper EOF checks and frame count validation within the mv_read_header() function. Organizations should also implement defensive measures such as setting resource limits on multimedia processing tasks, implementing input size validation, and conducting regular security assessments of multimedia processing pipelines. Additionally, the vulnerability aligns with ATT&CK technique T1499.001, which covers network denial of service attacks, and T1059.007, covering script-based execution, as the exploitation requires crafting specific input files that trigger the vulnerable code path. System administrators should also consider implementing sandboxing mechanisms and access controls to limit the impact of potential exploitation attempts.