Source: cve@mitre.org
vhe_u_mnt program in HP-UX allows local users to create root files through symlinks.
HP-UX systems are vulnerable to a local privilege escalation due to a flaw in the vhe_u_mnt program. This allows attackers to create root-owned files by exploiting a symlink vulnerability, granting them unauthorized access to the system. Successful exploitation leads to complete system compromise and potential data exfiltration.
Step 1: Symlink Creation: The attacker creates a symbolic link, for example, /tmp/evil_link, pointing to a sensitive system file like /etc/shadow or /etc/passwd.
Step 2: File Creation Trigger: The attacker executes a command or process that invokes vhe_u_mnt to create a file, likely in a controlled location.
Step 3: Race Condition: The attacker rapidly attempts to trigger vhe_u_mnt to create a file. The attacker's symbolic link is in place before the program can resolve the target.
Step 4: File Overwrite: If the race condition is successful, vhe_u_mnt creates a file (e.g., /tmp/some_file) owned by root, but its contents are determined by the attacker's symlink. The file created is actually the target of the symlink (e.g., /etc/shadow).
Step 5: Privilege Escalation: The attacker can then overwrite the target file (e.g., /etc/shadow) with a malicious entry, granting themselves root access.
The vulnerability lies within the vhe_u_mnt program, likely in how it handles file operations related to mounting virtual host environments. The program likely fails to properly validate the target of a symbolic link before creating a file, leading to a symlink race condition. An attacker can create a symbolic link pointing to a critical system file (e.g., /etc/shadow) and then trigger vhe_u_mnt to create a file with root privileges. The program's logic doesn't adequately check the link's destination, allowing the attacker to overwrite the target file with malicious content, thus gaining root access. The root cause is a lack of proper input validation and secure file operation handling, specifically the failure to resolve symbolic links before creating files with elevated privileges. This is a classic example of a TOCTOU (Time-of-Check to Time-of-Use) vulnerability.
This vulnerability is likely to be exploited by any threat actor with the knowledge and access to HP-UX systems. While no specific APT groups are directly linked to this CVE, it's a type of vulnerability that could be used by any attacker seeking to gain root access. CISA KEV: Not Listed.
Monitor system logs for suspicious activity related to vhe_u_mnt. Look for file creation events in unusual locations or with unexpected permissions.
Analyze file system changes, specifically the creation or modification of sensitive system files like /etc/shadow, /etc/passwd, and /etc/group.
Implement file integrity monitoring (FIM) to detect unauthorized changes to critical system files.
Network traffic analysis may reveal attempts to access or modify system files via remote access protocols (e.g., SSH) after a successful exploit.
Review audit logs for calls to vhe_u_mnt and related system calls (e.g., open, creat, symlink).
Apply security patches provided by HP/Hewlett-Packard. This is the primary and most effective remediation step.
Implement file system hardening by setting appropriate permissions on critical system files and directories.
Disable or remove the vhe_u_mnt program if it's not essential for system operation. This eliminates the attack surface.
Regularly review and audit system logs to detect suspicious activity.
Implement a robust intrusion detection and prevention system (IDPS) to monitor for and block malicious activity.
Use file integrity monitoring (FIM) tools to detect unauthorized changes to critical system files.
Implement least privilege principles, ensuring that users and processes have only the necessary permissions.