CVE-2021-35344 in tsMuxer
Summary
by MITRE • 12/03/2021
tsMuxer v2.6.16 was discovered to contain a heap-based buffer overflow via the function BitStreamReader::getCurVal in bitStream.h.
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Analysis
by VulDB Data Team • 12/09/2021
The vulnerability identified as CVE-2021-35344 affects tsMuxer version 2.6.16 and represents a critical heap-based buffer overflow condition within the BitStreamReader::getCurVal function located in bitStream.h. This flaw manifests when the application processes malformed or specially crafted input files, particularly those involving bitstream data manipulation. The vulnerability arises from insufficient bounds checking during the reading of bitstream data, allowing an attacker to write beyond the allocated heap memory boundaries. The affected component operates as part of the media file processing pipeline within tsMuxer, which is commonly used for muxing and demuxing transport stream files, making it a potentially significant threat vector for media processing applications.
The technical implementation of this vulnerability stems from improper memory management within the BitStreamReader class, specifically in how it handles bit position calculations and value retrieval operations. When the getCurVal function processes input data, it fails to validate the boundaries of the heap-allocated buffer before performing read operations. This oversight creates an exploitable condition where an attacker can craft input files that cause the function to access memory locations beyond the intended buffer limits. The heap-based nature of the overflow means that the corruption occurs in dynamically allocated memory regions, which can lead to arbitrary code execution or application crashes. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, though in this case it manifests as heap corruption due to the specific implementation details of the memory allocation pattern.
The operational impact of this vulnerability extends beyond simple application instability, as it can enable remote code execution when tsMuxer processes maliciously crafted media files. Attackers could leverage this flaw by preparing specially formatted transport stream files that trigger the vulnerable code path during normal file processing operations. The vulnerability affects both local and remote exploitation scenarios, particularly in environments where users might unknowingly process compromised media files or where automated processing systems handle untrusted input. Given tsMuxer's widespread use in video editing workflows, content distribution platforms, and media processing pipelines, the potential for widespread impact is significant. The vulnerability can result in complete system compromise when exploited, as successful exploitation allows attackers to execute arbitrary code with the privileges of the affected application.
Mitigation strategies for CVE-2021-35344 should prioritize immediate patching of tsMuxer to version 2.6.17 or later, which contains the necessary memory boundary checks and buffer overflow protections. Organizations should implement input validation measures that filter or sanitize all media files processed through tsMuxer, particularly those received from untrusted sources. Network segmentation and access controls should be enforced to limit exposure of systems running tsMuxer to potentially malicious input files. Security monitoring should include detection of abnormal memory usage patterns or unexpected crashes in tsMuxer processes, which could indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1203 as a means of achieving code execution through memory corruption, and organizations should consider implementing application whitelisting to prevent unauthorized versions of tsMuxer from executing. Regular security assessments of media processing workflows and vulnerability scanning of installed software versions should be conducted to identify and remediate similar issues across the enterprise environment.