CVE-2011-2913 in libmodplug
Summary
by MITRE
Off-by-one error in the CSoundFile::ReadAMS function in src/load_ams.cpp in libmodplug before 0.8.8.4 allows remote attackers to cause a denial of service (stack memory corruption) and possibly execute arbitrary code via a crafted AMS file with a large number of samples.
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Analysis
by VulDB Data Team • 12/03/2021
The vulnerability identified as CVE-2011-2913 represents a critical off-by-one error within the CSoundFile::ReadAMS function of libmodplug library version 0.8.8.4 and earlier. This flaw exists in the source file src/load_ams.cpp and demonstrates a classic buffer management issue that can be exploited to compromise system integrity. The vulnerability specifically targets the handling of AMS files, which are used for storing musical compositions in the MOD file format family, making it particularly dangerous in multimedia applications that process user-supplied audio content.
The technical implementation of this vulnerability stems from improper boundary checking during the parsing of AMS file structures. When the CSoundFile::ReadAMS function processes a crafted AMS file containing an excessive number of samples, the off-by-one error causes memory corruption in the stack memory region. This occurs because the function fails to properly validate the sample count parameter against the allocated buffer boundaries, leading to memory overwrite conditions that can corrupt adjacent stack variables and potentially overwrite return addresses or other critical execution data. The flaw aligns with CWE-129, which addresses improper validation of array indices, and represents a direct pathway for both denial of service and potential code execution scenarios.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential remote code execution capabilities. Attackers can craft malicious AMS files that, when processed by vulnerable applications, trigger the stack corruption and potentially allow arbitrary code execution with the privileges of the affected application. This makes the vulnerability particularly dangerous in web applications, media players, and other software that handles untrusted audio file formats. The remote exploitation capability means that attackers can deliver malicious files through various vectors including web downloads, email attachments, or file sharing platforms without requiring local system access.
Mitigation strategies for CVE-2011-2913 involve immediate patching of libmodplug to version 0.8.8.4 or later where the off-by-one error has been corrected through proper boundary validation. System administrators should implement comprehensive software update policies to ensure all affected applications using libmodplug are upgraded promptly. Additional protective measures include input validation at application level where AMS files are processed, implementing sandboxing techniques to isolate file processing operations, and deploying network-based intrusion detection systems that can identify suspicious file content patterns. The vulnerability demonstrates the importance of proper memory management in multimedia libraries and aligns with ATT&CK technique T1059 for execution through legitimate system interfaces, highlighting the need for robust input sanitization in audio processing frameworks. Organizations should also consider implementing automated vulnerability scanning tools that can identify legacy versions of libmodplug in their software inventory to prevent exploitation of this and similar memory corruption vulnerabilities.