Source: cve@mitre.org
HP-UX 9.x does not properly enable the Xauthority mechanism in certain conditions, which could allow local users to access the X display even when they have not explicitly been authorized to do so.
HP-UX 9.x systems are vulnerable to unauthorized access to the X display due to a flaw in the Xauthority mechanism. This allows local users to potentially intercept and control graphical sessions, leading to sensitive data exposure and system compromise. Successful exploitation grants attackers unauthorized access to the graphical user interface, enabling them to execute commands and potentially escalate privileges.
Step 1: Identify Target Display: The attacker identifies the target X display, typically by examining environment variables or by observing active X sessions using tools like ps or xwininfo.
Step 2: Locate Xauthority File: The attacker determines the location of the target user's Xauthority file, usually in the user's home directory (e.g., .Xauthority).
Step 3: Exploit the Vulnerability: Depending on the specific flaw, the attacker may attempt to read, overwrite, or manipulate the target user's Xauthority file. This could involve exploiting weak file permissions or a race condition during X server initialization.
Step 4: Establish Connection: The attacker connects to the target X display using the compromised Xauthority cookie. This allows them to interact with the target user's graphical session.
Step 5: Gain Control: The attacker can now execute commands, capture keystrokes, or otherwise interact with the target user's GUI, potentially leading to privilege escalation or data theft.
The vulnerability stems from a failure to properly enforce the Xauthority authentication mechanism under specific conditions within HP-UX 9.x. The Xauthority file, which stores authentication cookies for X11 connections, is not always correctly managed or protected. This leads to a scenario where a local user can potentially access the X display of another user without proper authorization. The root cause is likely a combination of factors, including improper file permissions on the Xauthority file, or a failure to correctly initialize or validate the Xauthority cookie during the X server startup process. This allows a rogue user to either read or overwrite the Xauthority file, effectively impersonating the legitimate user and gaining access to their graphical session. The lack of proper access control allows for a privilege escalation scenario where an attacker can interact with the graphical environment of a higher-privileged user.
Due to the age of the vulnerability and the specific operating system, it's unlikely to be actively targeted by sophisticated APTs. However, the underlying principles of Xauthority manipulation are relevant. Any threat actor with access to a vulnerable HP-UX 9.x system could exploit this vulnerability. This vulnerability is not listed in the CISA KEV catalog.
Monitor file access events for the .Xauthority file, looking for unauthorized reads or writes.
Analyze system logs for suspicious X server activity, such as unexpected connections or errors related to authentication.
Implement network monitoring to detect unauthorized X11 connections from unexpected sources.
Use file integrity monitoring tools to detect changes to the .Xauthority file.
Review process listings for suspicious X11 client processes.
Upgrade to a supported version of HP-UX that addresses the vulnerability. This is the primary and most effective remediation.
If upgrading is not possible, implement strict access controls on the .Xauthority file, ensuring that only the owner has read and write permissions.
Regularly audit system logs for suspicious activity related to X11 connections and authentication.
Consider disabling X11 forwarding if not required.
Implement a host-based intrusion detection system (HIDS) to monitor for malicious activity.