CVE-2017-17129 in libav
Summary
by MITRE
The ff_vc1_mc_4mv_chroma4 function in libavcodec/vc1_mc.c in Libav 12.2 allows remote attackers to cause a denial of service (segmentation fault and application crash) or possibly have unspecified other impact via a crafted file.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 12/12/2019
The vulnerability identified as CVE-2017-17129 resides within the Libav multimedia framework version 12.2, specifically in the ff_vc1_mc_4mv_chroma4 function located in the libavcodec/vc1_mc.c file. This flaw represents a critical security issue that affects the handling of video compression data, particularly within the VC1 video codec implementation. The vulnerability manifests when the software processes maliciously crafted video files that exploit improper memory management during chroma4 motion compensation operations.
The technical root cause of this vulnerability stems from inadequate input validation and memory boundary checking within the video decoding pipeline. When a specially crafted video file is processed, the ff_vc1_mc_4mv_chroma4 function fails to properly validate the incoming data structure, leading to memory corruption that results in segmentation faults and subsequent application crashes. This type of vulnerability falls under the CWE-125 vulnerability category, which encompasses out-of-bounds read conditions that can lead to memory corruption and system instability. The function's failure to properly validate motion vector parameters and chroma data structures creates an exploitable condition where attackers can manipulate the decoding process through carefully constructed input files.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially enable more sophisticated attack vectors. Remote attackers who can convince victims to process maliciously crafted video files can trigger application crashes that may be leveraged for further exploitation. The vulnerability affects any system utilizing Libav 12.2 for video processing, including media players, streaming servers, and content processing applications. This creates widespread exposure across various digital media ecosystems where Libav is integrated, particularly in environments handling untrusted video content from web sources, user uploads, or third-party media libraries.
From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where attackers can leverage software vulnerabilities to execute malicious code through media processing applications. The vulnerability's impact is particularly concerning in server environments where automated media processing occurs, as it can be exploited to create persistent denial of service conditions. Organizations running media processing services, content management systems, or any application that relies on Libav for video handling should consider this vulnerability as a potential entry point for attackers seeking to disrupt services or establish footholds within their networks.
The recommended mitigation strategies include immediate upgrade to Libav versions that contain patches addressing this vulnerability, typically those released after the vulnerability disclosure. System administrators should also implement input validation measures and sanitize all media files before processing, particularly those received from untrusted sources. Network-level defenses can include content filtering to block suspicious video files and implementing sandboxing techniques for media processing tasks. Additionally, regular security assessments of multimedia processing pipelines should be conducted to identify and remediate similar vulnerabilities that may exist in other components of the media handling stack. The vulnerability demonstrates the importance of rigorous input validation in multimedia processing libraries and highlights the need for comprehensive security testing of codec implementations that handle potentially malicious data streams.