CVE-2015-6819 in FFmpeg
Summary
by MITRE
Multiple integer underflows in the ff_mjpeg_decode_frame function in libavcodec/mjpegdec.c in FFmpeg before 2.7.2 allow remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted MJPEG data.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/14/2022
The vulnerability identified as CVE-2015-6819 represents a critical security flaw within the FFmpeg multimedia framework that affects versions prior to 2.7.2. This issue resides in the ff_mjpeg_decode_frame function located in the libavcodec/mjpegdec.c file, which handles the decoding of motion JPEG (MJPEG) video streams. The flaw manifests as multiple integer underflows that occur during the processing of specially crafted MJPEG data, creating a scenario where the application fails to properly validate input parameters before performing array indexing operations. Such vulnerabilities are particularly dangerous in multimedia processing libraries since they can be exploited through malicious media files that appear legitimate to users but contain carefully constructed data designed to trigger the underlying flaw.
The technical nature of this vulnerability stems from improper bounds checking within the MJPEG decoding logic where integer underflow conditions allow attackers to manipulate array indices to values that fall outside the allocated memory boundaries. When FFmpeg processes the malformed MJPEG data, the underflow conditions cause the decoder to attempt accessing memory locations that are either uninitialized or belong to other data structures within the application's memory space. This results in out-of-bounds array access that can lead to program crashes and denial of service conditions. According to CWE classification, this vulnerability maps to CWE-191 Integer Underflow (Wrap or Wraparound) which is a well-documented weakness in software security where arithmetic operations produce values that are smaller than the minimum value that can be represented by the data type.
The operational impact of CVE-2015-6819 extends beyond simple denial of service scenarios, as the unspecified other impacts mentioned in the vulnerability description suggest potential for more severe consequences including information disclosure or arbitrary code execution depending on the specific memory corruption patterns. Attackers can leverage this vulnerability by crafting malicious MJPEG files that, when processed by vulnerable FFmpeg implementations, trigger the integer underflow conditions. This makes the vulnerability particularly dangerous in environments where FFmpeg is used for processing untrusted media content such as web applications, media servers, or content management systems. The vulnerability affects a wide range of applications that depend on FFmpeg for multimedia processing, including but not limited to streaming services, video editing software, and media players.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1203 Exploitation for Client Execution which involves using vulnerabilities in client applications to execute malicious code. The attack surface is broad given FFmpeg's widespread adoption across various platforms and applications, making this vulnerability particularly attractive to threat actors seeking to compromise systems through media processing pipelines. The vulnerability is classified as a remote attack vector since malicious MJPEG data can be delivered over network connections without requiring local access to the target system. Organizations utilizing FFmpeg in their multimedia processing workflows should prioritize immediate patching and deployment of version 2.7.2 or later, which includes fixes for the integer underflow conditions. Additionally, implementing input validation and sanitization measures for all incoming media content, along with network segmentation and monitoring for unusual processing patterns, can provide additional layers of defense against exploitation attempts.