CVE-2016-9819 in libav
Summary
by MITRE
libavcodec/mpegvideo.c in libav 11.8 allows remote attackers to cause a denial of service (crash) via vectors involving left shift of a negative value.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 09/03/2020
The vulnerability identified as CVE-2016-9819 resides within the libavcodec library version 11.8, specifically in the mpegvideo.c file where a critical flaw exists in the handling of bitwise operations. This issue manifests when the software processes multimedia content, particularly MPEG video streams, and encounters malformed input data that triggers unexpected behavior during left shift operations. The flaw represents a classic integer overflow condition where negative values are subjected to left shift operations, leading to undefined behavior that can result in system instability.
The technical implementation of this vulnerability involves the manipulation of signed integer values during video decoding processes. When libav encounters specific malformed MPEG video data, the decoder attempts to perform left shift operations on negative integers, which violates the fundamental principles of signed integer arithmetic. This condition violates the expected data flow patterns within the multimedia processing pipeline, causing the application to crash or become unresponsive. The vulnerability is categorized under CWE-191 as an integer underflow or wraparound, which is a common class of issues in low-level programming where arithmetic operations exceed the representable range of the data type.
From an operational perspective, this vulnerability presents a significant risk to systems that process multimedia content, particularly those exposed to untrusted input sources such as web applications, media servers, or content delivery networks. Remote attackers can exploit this weakness by crafting malicious MPEG video files that, when processed by vulnerable libav implementations, will trigger the denial of service condition. The impact extends beyond simple system crashes to potentially disrupt service availability for legitimate users, making this a critical concern for organizations maintaining multimedia processing infrastructure.
The ATT&CK framework categorizes this vulnerability under T1499.004 as "Endpoint Denial of Service" within the Defense Evasion and Impact domains, as it allows adversaries to consume system resources or cause system instability. The exploitation requires minimal privileges and can be automated, making it particularly dangerous in environments where multimedia processing is automated or where users can upload content. Security practitioners should consider this vulnerability as part of broader multimedia processing attack surface analysis, particularly in web applications that utilize libav for video transcoding or processing.
Mitigation strategies for CVE-2016-9819 should include immediate patching of libav installations to versions that address the integer handling issue in mpegvideo.c. Organizations should also implement input validation measures that filter or sanitize multimedia content before processing, particularly when dealing with untrusted sources. Additionally, deployment of network segmentation and content filtering solutions can help reduce the attack surface by limiting exposure to potentially malicious multimedia content. System monitoring should include detection of abnormal resource consumption patterns that might indicate exploitation attempts, and regular security assessments should verify that all multimedia processing components are updated to prevent similar vulnerabilities from affecting operational systems.