Source: cve@mitre.org
Unspecified vulnerability in pt_chmod in SCO UNIX 4.2 and earlier allows local users to gain root access.
SCO UNIX 4.2 and earlier systems are vulnerable to a local privilege escalation via a flaw in the pt_chmod utility, allowing attackers to gain root access. This vulnerability, dating back to 1994, presents a significant risk to legacy systems, enabling complete system compromise with a simple local exploit. The lack of detailed information makes precise exploitation challenging, but the potential impact is severe.
Step 1: Preparation: The attacker logs into the vulnerable SCO UNIX system with a low-privilege account.
Step 2: Identify Target: The attacker identifies the pt_chmod utility and its associated files or processes.
Step 3: Exploit Trigger: The attacker crafts a malicious input or sequence of actions that triggers the vulnerability in pt_chmod.
Step 4: Permission Manipulation: The exploit leverages a race condition or other flaw to manipulate the permissions of a critical system file or process, likely related to the pseudo-terminal device.
Step 5: Privilege Escalation: The attacker gains root access by exploiting the manipulated permissions.
The vulnerability lies within the pt_chmod utility, which likely mishandles permissions or file ownership changes related to pseudo-terminals (pty). The unspecified nature suggests a flaw in how pt_chmod interacts with the kernel or other system components when setting permissions on these terminal devices. A likely root cause is a race condition or a TOCTOU (Time-of-Check to Time-of-Use) vulnerability. The utility might check a file's state (e.g., ownership) and then, based on that check, perform an action (e.g., change permissions). If the file's state changes between the check and the action, an attacker could potentially manipulate the system to gain elevated privileges. Without specific details, it is difficult to pinpoint the exact function or logic flaw, but the core problem is likely a failure to properly handle the security implications of changing permissions on special files like ptys.
Due to the age of the vulnerability, it's unlikely to be actively exploited by sophisticated APTs. However, it could be leveraged by less sophisticated attackers or incorporated into automated exploitation frameworks targeting legacy systems. This vulnerability is not listed in the CISA KEV catalog.
Monitor system logs for suspicious activity related to pt_chmod or pseudo-terminal devices.
Analyze file system changes, specifically permission modifications on critical system files.
Look for unusual processes or connections originating from low-privilege accounts.
Implement file integrity monitoring to detect unauthorized changes to system binaries and configuration files.
Network monitoring for unusual traffic patterns associated with privilege escalation attempts.
Upgrade to a supported version of SCO UNIX that addresses the vulnerability. This is the most effective solution.
If upgrading is not possible, apply any available security patches or workarounds provided by SCO (if any exist).
Restrict access to the pt_chmod utility to only necessary users.
Implement strict access controls and least privilege principles for all users.
Regularly audit system logs and security configurations.
Consider using a host-based intrusion detection system (HIDS) to monitor for malicious activity.