CVE-2010-3386 in ust
Summary
by MITRE
usttrace in LTTng Userspace Tracer (aka UST) 0.7 places 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 • 02/07/2019
The vulnerability identified as CVE-2010-3386 resides within the LTTng Userspace Tracer component known as usttrace, specifically affecting version 0.7 of the LTTng (Linux Trace Toolkit next generation) system. This flaw manifests in how the tracer handles library path resolution during runtime execution, creating a privilege escalation vector that can be exploited by local attackers. The issue stems from the improper handling of the LD_LIBRARY_PATH environment variable, which is a critical component in Unix-like operating systems for determining where shared libraries should be loaded from during program execution.
The technical flaw occurs when usttrace processes a zero-length directory name within the LD_LIBRARY_PATH variable. This seemingly innocuous condition creates a dangerous situation where the dynamic linker interprets the empty directory entry as a valid path that should be searched for shared libraries. When a user executes a program that relies on usttrace for tracing, the system attempts to load shared libraries from the current working directory due to this malformed path entry. This behavior represents a fundamental violation of secure library loading practices and creates an opportunity for privilege escalation attacks.
The operational impact of this vulnerability is significant for systems utilizing LTTng tracing capabilities, particularly in environments where multiple users share the same system or where applications might be executed with elevated privileges. Attackers can exploit this weakness by placing a malicious shared library file in the current working directory, which will then be loaded and executed with the privileges of the process that calls usttrace. This creates a classic Trojan horse scenario where legitimate system processes unknowingly execute attacker-controlled code, potentially leading to full system compromise or privilege escalation to root level access.
This vulnerability aligns with CWE-426, which describes the weakness of Untrusted Search Path, and demonstrates how improper handling of environment variables can lead to security issues. The attack pattern corresponds to techniques described in the MITRE ATT&CK framework under privilege escalation tactics, specifically focusing on the use of malicious libraries to gain elevated privileges. The flaw represents a failure in proper input validation and environment variable sanitization, which are fundamental security practices that should prevent such dangerous path resolution behaviors.
Mitigation strategies for this vulnerability include immediate patching of the LTTng Userspace Tracer component to version 0.8 or later, where the issue has been resolved through proper handling of empty directory entries in LD_LIBRARY_PATH. System administrators should also implement proper environment variable sanitization procedures, ensuring that zero-length or malformed path entries are filtered out before process execution. Additionally, implementing secure library loading practices such as using the LD_LIBRARY_PATH with explicit absolute paths rather than relying on current working directory resolution can help prevent similar issues. Regular security audits of environment variable handling within tracing and monitoring tools should be conducted to identify and remediate similar vulnerabilities that could potentially allow privilege escalation attacks.