CVE-2010-3394 in texmacs
Summary
by MITRE
The (1) texmacs and (2) tm_mupad_help scripts in TeXmacs 1.0.7.4 place a zero-length directory name in the LD_LIBRARY_PATH, which allows local users to gain privileges via a Trojan horse shared library in the current working directory.
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Analysis
by VulDB Data Team • 09/27/2021
The vulnerability identified as CVE-2010-3394 affects TeXmacs version 1.0.7.4 and specifically involves two scripts named texmacs and tm_mupad_help that exhibit insecure library loading behavior. This flaw creates a privilege escalation vector through improper handling of the dynamic library search path environment variable. The technical implementation places a zero-length directory entry within the LD_LIBRARY_PATH variable, which fundamentally alters how the system resolves shared library dependencies during script execution. According to CWE-426, this represents an insecure library loading vulnerability where the application fails to properly validate or sanitize the library search path, creating an exploitable condition that allows malicious code execution with elevated privileges.
The operational impact of this vulnerability manifests when local users exploit the zero-length directory entry in LD_LIBRARY_PATH to execute arbitrary code with the privileges of the running process. The attacker can place a malicious shared library file in the current working directory, and when the vulnerable script executes, the system will load this malicious library instead of the legitimate one. This technique leverages the default behavior of dynamic linkers where empty directory entries in LD_LIBRARY_PATH are interpreted as the current working directory, effectively bypassing normal security boundaries. The vulnerability directly maps to ATT&CK technique T1068 which describes the use of privilege escalation through insecure library loading mechanisms, and T1546 which covers the abuse of dynamic linkers for code injection.
The root cause of this vulnerability stems from the improper handling of environment variables during script execution, specifically the LD_LIBRARY_PATH variable which controls where the dynamic linker searches for shared libraries. When a zero-length directory is included in the path, it creates an implicit reference to the current working directory, allowing local users to inject malicious code simply by placing a shared library file in the directory from which the vulnerable script is executed. The flaw demonstrates poor security practices in environment variable manipulation and lacks proper input validation or sanitization of library search paths. This vulnerability is particularly concerning because it requires no special permissions beyond local access to exploit, making it a significant concern for systems where local user access cannot be fully trusted. Organizations should immediately update to patched versions of TeXmacs or implement workarounds that properly sanitize environment variables before executing vulnerable scripts. The vulnerability also highlights the importance of following secure coding practices for environment variable handling and demonstrates how seemingly minor implementation flaws can result in serious privilege escalation capabilities.