CVE-2018-14448 in Untrunc
Summary
by MITRE
Codec::parse in track.cpp in Untrunc through 2018-06-07 has a NULL pointer dereference via a crafted MP4 file because of improper interaction with libav.
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Analysis
by VulDB Data Team • 04/25/2023
The vulnerability identified as CVE-2018-14448 represents a critical NULL pointer dereference flaw within the Untrunc media processing tool, specifically within the Codec::parse function located in track.cpp. This vulnerability affects all versions of Untrunc up to and including the release dated 2018-06-07, creating a significant security risk for users who process media files through this tool. The flaw stems from improper interaction between Untrunc's codebase and the underlying libav library, which is commonly used for multimedia file handling and processing. When a maliciously crafted MP4 file is processed by Untrunc, the application fails to properly validate input data structures, leading to a situation where a null pointer is dereferenced during the parsing operation.
The technical implementation of this vulnerability involves the Codec::parse function attempting to access memory locations that have not been properly initialized or validated. This occurs when Untrunc encounters specific malformed data within the MP4 file structure that libav processes, causing the application to proceed with operations on uninitialized pointers. The interaction with libav introduces complexity because the library's handling of certain edge cases in MP4 file structures does not properly communicate expected states back to Untrunc's parsing logic. This creates a scenario where Untrunc assumes certain data structures exist and are properly initialized, but when they are null or improperly formatted, the application crashes with a NULL pointer dereference exception. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference issues, and can be classified as a software fault that leads to application instability.
The operational impact of this vulnerability extends beyond simple application crashes, as it represents a potential vector for denial of service attacks against systems that rely on Untrunc for media processing. An attacker could craft a malicious MP4 file that, when processed by Untrunc, would cause the application to terminate unexpectedly, potentially disrupting legitimate media processing workflows. In environments where Untrunc is used for automated media handling or as part of larger processing pipelines, this vulnerability could be exploited to create service disruptions or to prevent legitimate users from processing their media files. The vulnerability also has implications for systems that might automatically process user-uploaded media content through Untrunc, as it could be used to target such systems and cause operational failures.
Mitigation strategies for CVE-2018-14448 primarily focus on updating to the latest version of Untrunc where the vulnerability has been addressed through proper input validation and error handling mechanisms. Users should immediately upgrade to versions released after June 7, 2018, when the fix was implemented to prevent the NULL pointer dereference. Additionally, implementing proper input validation measures at the application level can help detect and reject malformed MP4 files before they reach the Codec::parse function. Organizations should also consider implementing sandboxing techniques when processing untrusted media files, as recommended by the ATT&CK framework's mitigation strategies for software exploitation techniques. Network-level filtering and content validation should be implemented to prevent potentially malicious media files from reaching systems that utilize Untrunc, particularly in environments where automated processing occurs. The fix implemented by the developers likely involved adding proper null checks and validation routines to ensure that libav's output is properly verified before being used in subsequent processing steps, thereby preventing the NULL pointer dereference condition that led to the vulnerability.