CVE-2017-18245 in libav
Summary
by MITRE
The mpc8_probe function in libavformat/mpc8.c in Libav 12.2 allows remote attackers to cause a denial of service (heap-based buffer over-read) via a crafted audio file.
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Analysis
by VulDB Data Team • 02/22/2023
The vulnerability identified as CVE-2017-18245 represents a critical heap-based buffer over-read flaw within the libav multimedia framework version 12.2. This issue specifically affects the mpc8_probe function located in the libavformat/mpc8.c file, which is responsible for probing and identifying multimedia file formats. The flaw enables remote attackers to craft malicious audio files that trigger unintended memory access patterns during format detection and parsing operations.
The technical nature of this vulnerability stems from inadequate input validation and bounds checking within the mpc8_probe function. When processing specially crafted audio files, the function attempts to read memory locations beyond the allocated buffer boundaries, resulting in a heap-based buffer over-read condition. This occurs because the code does not properly validate the size or structure of the input data before performing memory operations, allowing attackers to manipulate the parsing logic through carefully constructed file headers or metadata fields.
From an operational perspective, this vulnerability creates significant denial of service risks for systems utilizing libav for multimedia processing. Remote attackers can exploit this flaw by simply providing a maliciously crafted audio file to any application that uses libav for format detection, potentially causing application crashes, system instability, or complete service interruption. The impact extends beyond simple service disruption as it can be leveraged in broader attack chains where multiple applications rely on the same vulnerable library components.
The vulnerability maps directly to CWE-125, which describes "Out-of-bounds Read" conditions, and aligns with ATT&CK technique T1499.004 for "Network Denial of Service" through application-level exploitation. This classification indicates that the attack vector targets application-level software rather than network infrastructure, making it particularly dangerous in environments where multimedia processing is automated or exposed to untrusted input sources. The exploitability of this vulnerability is enhanced by the fact that many multimedia applications and services automatically probe files for format detection without proper input sanitization.
Mitigation strategies for CVE-2017-18245 require immediate patching of affected libav installations to version 12.3 or later, which includes the necessary bounds checking and input validation fixes. Organizations should also implement input filtering mechanisms that validate audio file structures before processing, employ sandboxing techniques for multimedia file handling, and consider network-level restrictions on file uploads to prevent exploitation. Additionally, regular vulnerability assessments and security updates should be implemented to maintain protection against similar buffer over-read vulnerabilities in multimedia processing frameworks, as these types of flaws remain prevalent in complex multimedia libraries due to the intricate nature of format parsing and memory management requirements.