CVE-2018-20861 in libopenmpt
Summary
by MITRE
libopenmpt before 0.3.11 allows a crash with certain malformed custom tunings in MPTM files.
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Analysis
by VulDB Data Team • 07/15/2020
The vulnerability identified as CVE-2018-20861 affects the libopenmpt library version 0.3.10 and earlier, representing a critical software flaw that manifests through improper handling of malformed custom tunings within MPTM music files. This library serves as a crucial component for playing various module music formats including MOD, S3M, IT, and MPTM files, making it an essential element in audio playback applications across multiple platforms. The issue specifically arises when the library attempts to process custom tuning data embedded within MPTM files, which are used to define alternative pitch mappings for instruments in module music formats. When encountering malformed or corrupted tuning information, the library fails to properly validate input data, leading to a crash condition that can result in application termination and potential denial of service for end users.
The technical nature of this vulnerability stems from inadequate input validation and memory management within the libopenmpt parsing routines. According to CWE classification, this represents a weakness categorized under CWE-125: "Out-of-bounds Read" and potentially CWE-787: "Out-of-bounds Write," where the library attempts to access memory locations beyond the allocated buffer boundaries when processing custom tuning parameters. The flaw occurs during the parsing phase of MPTM file structures, particularly when the software encounters unexpected data patterns in the tuning information section of these files. This type of vulnerability falls within the ATT&CK framework under the technique T1203: "Exploitation for Client Execution" as it can be exploited through crafted media files to cause application crashes, and potentially T1499.004: "Endpoint Denial of Service" when leveraged in malicious contexts. The vulnerability demonstrates a classic buffer over-read scenario where the library's parser does not properly bounds-check the custom tuning data, leading to memory corruption and subsequent application instability.
The operational impact of this vulnerability extends beyond simple application crashes to potentially compromise system stability in environments where libopenmpt is integrated into multimedia applications, music players, or game engines that utilize module file formats. Attackers could exploit this weakness by distributing malicious MPTM files designed to trigger the crash condition, effectively creating a denial of service scenario for users of affected applications. This vulnerability is particularly concerning in scenarios where applications automatically process or preview media files, as the crash could occur without user intervention. The impact is amplified in professional audio applications, music composition software, and gaming environments where module file formats are commonly used, potentially affecting both end users and developers who rely on stable library functionality. Additionally, the vulnerability could serve as a vector for more sophisticated attacks if combined with other memory corruption issues, though the immediate impact is primarily focused on crash conditions rather than arbitrary code execution.
Mitigation strategies for CVE-2018-20861 involve immediate upgrading to libopenmpt version 0.3.11 or later, which includes proper input validation and bounds checking for custom tuning data processing. System administrators and developers should implement comprehensive testing procedures for file validation before processing module music files, particularly in applications that automatically handle user-uploaded content. The recommended approach includes deploying defensive programming practices such as input sanitization, memory bounds checking, and implementing proper error handling mechanisms within applications that utilize libopenmpt. Organizations should also consider implementing file type validation and content scanning for MPTM files to prevent exploitation, while maintaining regular software update schedules to address similar vulnerabilities in multimedia libraries. Security monitoring should be enhanced to detect potential exploitation attempts through malformed media files, particularly in environments where automated processing of user content occurs. The vulnerability highlights the importance of robust input validation in multimedia libraries and serves as a reminder of the critical security considerations when handling complex binary file formats that contain embedded parameter data.