CVE-2016-2327 in FFmpeg
Summary
by MITRE
libavcodec/pngenc.c in FFmpeg before 2.8.5 uses incorrect line sizes in certain row calculations, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via a crafted .avi file, related to the apng_encode_frame and encode_apng functions.
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Analysis
by VulDB Data Team • 07/08/2022
The vulnerability identified as CVE-2016-2327 resides within the FFmpeg multimedia framework's libavcodec module, specifically in the pngenc.c file responsible for handling png encoding operations. This flaw affects FFmpeg versions prior to 2.8.5 and represents a critical security issue that can be exploited through maliciously crafted avi files containing animated png content. The vulnerability stems from improper handling of line size calculations during the encoding process, creating a scenario where attackers can manipulate the software's memory access patterns.
The technical root cause of this vulnerability involves incorrect line size computations within the apng_encode_frame and encode_apng functions that process animated png data within avi containers. When FFmpeg encounters a specially crafted avi file with malformed apng data, the software calculates row dimensions incorrectly, leading to out-of-bounds array access during memory operations. This miscalculation occurs because the line size parameters are not properly validated against the actual data structure boundaries, allowing attackers to manipulate the encoding logic through carefully constructed input files. The flaw falls under CWE-129 Input Validation and CWE-787 Out-of-bounds Write, representing both validation weaknesses and memory corruption issues.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more severe consequences including arbitrary code execution or system instability. Remote attackers can leverage this vulnerability by preparing a malicious avi file containing crafted apng frames that trigger the faulty line size calculations. When the vulnerable FFmpeg instance processes such files, either through media players, content management systems, or automated processing pipelines, the incorrect memory access patterns can result in crashes, memory corruption, or even potential privilege escalation depending on the execution context. This vulnerability particularly affects applications that rely on FFmpeg for video processing, streaming services, and content delivery platforms that handle user-uploaded media files.
Mitigation strategies for CVE-2016-2327 primarily focus on immediate software updates and input validation measures. Organizations should prioritize upgrading to FFmpeg version 2.8.5 or later where the vulnerability has been addressed through proper line size calculations and bounds checking. Additionally, implementing strict input validation for media files, particularly those containing animated png content, can help prevent exploitation attempts. Network-based mitigations include filtering avi files at ingress points and implementing sandboxing mechanisms for media processing tasks. Security teams should also consider deploying intrusion detection systems that can identify suspicious media file patterns and monitor for exploitation attempts. The vulnerability demonstrates the importance of proper memory management in multimedia processing libraries and aligns with ATT&CK technique T1203 Exploitation for Client Execution, where attackers leverage software vulnerabilities to execute malicious code through media processing applications.