CVE-2010-3369 in mono-debugger
Summary
by MITRE
The (1) mdb and (2) mdb-symbolreader scripts in mono-debugger 2.4.3, and other versions before 2.8.1, 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 • 02/07/2019
The vulnerability identified as CVE-2010-3369 affects the mono-debugger package version 2.4.3 and earlier, specifically impacting the mdb and mdb-symbolreader scripts. This issue represents a classic path traversal and privilege escalation vulnerability that exploits how the system handles library loading through environment variables. The flaw manifests when these debugger scripts execute with a zero-length directory name appended to the LD_LIBRARY_PATH environment variable, creating a dangerous condition where the system will search the current working directory for shared libraries before examining standard system paths. This behavior directly violates secure coding principles and creates an exploitable condition where malicious actors can place Trojan horse shared libraries in the current working directory to gain elevated privileges. The vulnerability is classified under CWE-428, which addresses the improper use of system calls that can lead to privilege escalation through environment variable manipulation.
The technical implementation of this vulnerability stems from how the debugger scripts construct the LD_LIBRARY_PATH environment variable during execution. When the scripts are invoked, they append an empty directory entry to the library path, effectively creating a search order where the current working directory is prioritized for library loading. This occurs because the empty directory entry translates to a search of the current directory, allowing any shared library with the same name as a system library to be loaded instead of the legitimate system version. The attack vector relies on local users who can manipulate the current working directory, placing malicious shared libraries that mimic legitimate system libraries such as libc or other critical components. This technique falls under the ATT&CK framework category of privilege escalation through environment variable manipulation and library injection, specifically targeting the execution environment and library loading mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially enable full system compromise when the debugger scripts are executed by users with elevated privileges or in contexts where they might be invoked by unprivileged users. The vulnerability is particularly concerning because it does not require network access or complex exploitation techniques, making it highly accessible to local attackers. When exploited successfully, the malicious shared library can execute arbitrary code with the privileges of the user running the debugger script, potentially allowing attackers to escalate privileges to root or other high-privilege accounts. The vulnerability affects systems where mono-debugger is installed and used, creating a persistent threat vector that remains active until the affected version is patched or the scripts are modified to properly handle library paths. The issue demonstrates poor input validation and environment variable handling practices that are fundamental to secure system design and aligns with common software security weaknesses outlined in industry standards.
Mitigation strategies for CVE-2010-3369 focus primarily on upgrading to patched versions of mono-debugger, specifically version 2.8.1 or later where the problematic library path handling has been corrected. System administrators should ensure that all instances of the affected scripts are updated and that no older versions remain accessible or executable. Additionally, organizations should implement monitoring for unauthorized changes to the mono-debugger package and establish regular patch management processes to address similar vulnerabilities. The vulnerability highlights the importance of proper environment variable handling and secure library loading practices, which should be enforced through secure coding guidelines and automated security testing. Organizations may also consider implementing additional security controls such as file integrity monitoring, privilege separation, and restricting execution of debugger scripts to trusted users only. The remediation process should include verification that the LD_LIBRARY_PATH is properly constructed without empty directory entries and that shared library loading follows secure search order principles. This vulnerability serves as a reminder of the critical importance of environment variable security and proper library loading mechanisms in preventing local privilege escalation attacks.