CVE-2004-1894 in Mlink
Summary
by MITRE
TEXutil in ConTEXt, when executed with the --silent option, allows local users to overwrite arbitrary files via a symlink attack on texutil.log.
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Analysis
by VulDB Data Team • 07/16/2017
The vulnerability identified as CVE-2004-1894 resides within the TEXutil component of the ConTEXt document preparation system, specifically when the application is invoked with the --silent command-line option. This flaw represents a classic symlink attack vector that enables local attackers to manipulate file system operations through carefully crafted symbolic link manipulation. The vulnerability manifests when TEXutil creates or modifies the texutil.log file during its execution under silent mode conditions, creating an opportunity for privilege escalation and unauthorized file modification.
The technical implementation of this vulnerability stems from improper handling of temporary files and log generation processes within the TEXutil utility. When executed with --silent, the application operates without displaying output to the terminal but continues to generate log files for internal processing. The flaw occurs because TEXutil does not properly validate or sanitize the file paths associated with the log file creation, allowing an attacker to establish symbolic links that point to sensitive system files or locations where the application might attempt to write data. This represents a direct violation of the principle of least privilege and proper file system access controls.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities, as it can be leveraged to compromise system integrity and potentially escalate privileges. Local users who can execute TEXutil with the --silent option gain the ability to overwrite files in directories where the application has write permissions, potentially targeting configuration files, system binaries, or other sensitive resources. The vulnerability is particularly concerning because it operates silently without user intervention, making detection difficult and allowing attackers to perform malicious file modifications without raising immediate alerts. This aligns with ATT&CK technique T1059.007 for executing malicious code through command-line interfaces and represents a privilege escalation vector through file system manipulation.
Mitigation strategies for this vulnerability require careful attention to file system permissions and proper input validation within the application. System administrators should ensure that the TEXutil utility is not executed with unnecessary privileges, particularly when using the --silent option, and that the working directory does not contain writable symbolic links. The recommended approach involves implementing proper file path validation and ensuring that temporary files are created with unique names and appropriate permissions to prevent symlink attacks. Organizations should also consider updating to newer versions of ConTEXt that have addressed this vulnerability through proper file handling procedures and enhanced security controls. This vulnerability type maps to CWE-367, which specifically addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions, and demonstrates the importance of proper file system access controls in preventing unauthorized file manipulation attacks.