CVE-2016-7555 in FFmpeg
Summary
by MITRE
The avi_read_header function in libavformat/avidec.c in FFmpeg before 3.1.4 is vulnerable to memory leak when decoding an AVI file that has a crafted "strh" structure.
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Analysis
by VulDB Data Team • 07/15/2019
The vulnerability identified as CVE-2016-7555 represents a critical memory management flaw within the FFmpeg multimedia framework, specifically affecting the avi_read_header function in the libavformat/avidec.c component. This issue manifests when processing AVI files containing deliberately crafted "strh" structures that exploit improper memory allocation and deallocation mechanisms. The flaw resides in the handling of stream header information within AVI containers, where the decoder fails to properly release allocated memory resources when encountering malformed stream headers, leading to progressive memory consumption that can ultimately result in application instability or denial of service conditions.
The technical exploitation of this vulnerability stems from insufficient input validation and memory management practices within the AVI demultiplexer. When FFmpeg encounters an AVI file with a crafted "strh" structure, the avi_read_header function attempts to allocate memory for stream header information but fails to properly clean up these allocations when subsequent validation checks fail or when the malformed structure triggers early termination paths. This memory leak occurs because the function does not implement proper error handling that ensures all allocated memory blocks are freed before returning from the function, creating a resource exhaustion scenario that can be systematically exploited by attackers.
From an operational perspective, this vulnerability poses significant risks to applications and systems that utilize FFmpeg for media processing, including content delivery networks, video streaming services, and multimedia applications. The memory leak can be leveraged to cause progressive memory consumption that eventually leads to system instability, application crashes, or complete system resource exhaustion. Attackers can craft malicious AVI files that, when processed by vulnerable FFmpeg implementations, will continuously consume system memory until the application becomes unresponsive or the system experiences performance degradation that impacts legitimate users.
The vulnerability aligns with CWE-401, which specifically addresses improper handling of memory allocation failures and memory leaks in software systems. This classification emphasizes the fundamental flaw in resource management where allocated memory is not properly released, creating persistent memory consumption patterns that can be exploited for denial of service attacks. The flaw also relates to ATT&CK technique T1499.004, which covers the exploitation of memory corruption vulnerabilities for resource exhaustion attacks, demonstrating how this vulnerability can be weaponized to degrade system performance through sustained memory consumption.
Mitigation strategies for CVE-2016-7555 primarily focus on immediate patch application to FFmpeg versions 3.1.4 and later, which contain the necessary fixes to properly handle memory allocation and deallocation in the avi_read_header function. Organizations should implement comprehensive input validation for all media files processed through FFmpeg, particularly when handling untrusted content, by employing sandboxing techniques and limiting memory consumption through resource monitoring. Additionally, system administrators should deploy network-based intrusion detection systems that can identify and block suspicious media file processing patterns that might indicate exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to ensure that all FFmpeg installations are properly updated and that no legacy versions remain in production environments, as this vulnerability can be exploited across various platforms and applications that rely on FFmpeg for multimedia processing capabilities.