CVE-2016-7122 in FFmpeg
Summary
by MITRE
The avi_read_nikon function in libavformat/avidec.c in FFmpeg before 3.1.4 is vulnerable to infinite loop when it decodes an AVI file that has a crafted 'nctg' structure.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability identified as CVE-2016-7122 represents a critical security flaw in FFmpeg's handling of AVI file formats, specifically within the avi_read_nikon function located in libavformat/avidec.c. This issue affects FFmpeg versions prior to 3.1.4 and demonstrates a classic example of an infinite loop vulnerability that can be exploited through carefully crafted media files. The flaw manifests when the decoder encounters an AVI file containing a maliciously constructed 'nctg' structure, which triggers an unintended execution path that results in an infinite loop during the decoding process.
The technical implementation of this vulnerability stems from inadequate input validation and boundary checking within the avi_read_nikon function. When FFmpeg processes an AVI file with a malformed 'nctg' chunk, the parsing logic fails to properly validate the structure's parameters and size indicators. This deficiency allows an attacker to construct an AVI file where the 'nctg' structure contains malformed data that causes the decoder to enter an infinite loop while attempting to parse the chunk. The vulnerability is categorized under CWE-835, which specifically addresses the issue of loops that do not contain a reinitialization of loop variables, leading to potential denial of service conditions.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it can be leveraged to create persistent denial of service attacks against systems that process AVI media files. Applications relying on FFmpeg for video processing, including media players, content management systems, and streaming platforms, become vulnerable to exploitation when they encounter maliciously crafted AVI files. The infinite loop behavior consumes CPU resources continuously without making progress, effectively rendering the affected system or application unresponsive until manual intervention occurs. This type of vulnerability aligns with ATT&CK technique T1499.004, which covers "File and Directory Permissions Modification" in the context of denial of service through resource exhaustion.
Mitigation strategies for CVE-2016-7122 primarily focus on upgrading to FFmpeg version 3.1.4 or later, where the vulnerability has been patched through enhanced input validation and proper boundary checking in the avi_read_nikon function. Organizations should also implement additional defensive measures such as input sanitization for media files, implementing timeout mechanisms for file processing operations, and deploying network-based intrusion detection systems that can identify suspicious media file patterns. The patch addresses the root cause by ensuring that the 'nctg' structure parsing logic properly validates chunk sizes and parameters, preventing the infinite loop condition from occurring. Security teams should also consider implementing sandboxing techniques for media processing and establishing strict file format validation procedures to prevent exploitation through malicious media content.