CVE-2001-1092 in Tru64
Summary
by MITRE
msgchk in Digital UNIX 4.0G and earlier allows a local user to read the first line of arbitrary files via a symlink attack on the .mh_profile file.
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Analysis
by VulDB Data Team • 01/10/2025
The vulnerability described in CVE-2001-1092 represents a classic privilege escalation and information disclosure flaw affecting Digital UNIX systems running version 4.0G and earlier. This issue resides within the msgchk utility, which is part of the mail handling subsystem of the operating system. The vulnerability stems from improper handling of symbolic links during file operations, creating a race condition that allows local attackers to access sensitive information from arbitrary files on the system.
The technical implementation of this vulnerability exploits a weakness in how the msgchk utility processes the .mh_profile file during message checking operations. When the utility processes mail messages, it creates temporary symbolic links to the user's .mh_profile file without proper validation of the symbolic link targets. A local attacker can create a malicious symbolic link pointing to a sensitive file such as /etc/passwd or another system configuration file, then trigger the msgchk utility to follow this link. Since the utility reads the first line of the targeted file through the symbolic link, it inadvertently exposes the contents of files that should remain protected.
This vulnerability directly maps to CWE-59 and CWE-22 within the Common Weakness Enumeration framework, specifically addressing improper link resolution and path traversal issues. The flaw operates under the ATT&CK framework as a privilege escalation technique through local exploitation, specifically categorized under T1068 (Local Privilege Escalation) and T1566 (Phishing for Information). The attack vector requires local system access but does not need network connectivity, making it particularly dangerous in multi-user environments where attackers might have limited initial access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to potentially gather sensitive system information that could be used for further exploitation. The ability to read the first line of arbitrary files means that attackers can extract user credentials, system configuration details, or other sensitive data that might reveal system architecture or user account information. This information could then be leveraged to perform more sophisticated attacks such as credential harvesting, privilege escalation, or targeted social engineering campaigns. The vulnerability is particularly concerning because it affects the core mail handling functionality of the operating system, which is typically used by multiple users and may contain sensitive information.
Mitigation strategies for this vulnerability should include immediate system updates and patches provided by Digital Equipment Corporation, as well as implementing proper file access controls and monitoring for suspicious symbolic link creation. System administrators should also review and tighten the permissions on sensitive files and directories, particularly those related to mail handling and user profiles. The implementation of mandatory access controls and regular security audits can help detect and prevent similar vulnerabilities from being exploited. Additionally, organizations should consider implementing file integrity monitoring solutions to detect unauthorized symbolic link creation and other malicious file system modifications that could be used to exploit this class of vulnerability.