Executive brief
A vulnerability in the Character-Terminal User Environment (CUE) on older HP-UX systems allows local users to gain full administrative control. By exploiting how the system handles temporary error files, a standard user can overwrite critical system files like the password database. This can lead to a complete system takeover, data loss, or permanent disruption of operations.
Technical details
The Character-Terminal User Environment (CUE) utility in HP-UX (specifically version 11.0 and earlier, including 10.20) contains a symlink vulnerability. The application, which runs with setuid root privileges, fails to properly validate the 'IOERROR.mytty' file before writing to it. A local attacker can manipulate the environment by setting a specific LOGNAME and umask, then creating a symbolic link from 'IOERROR.mytty' to a sensitive system file (such as /etc/passwd). When CUE is executed, it follows the symlink and overwrites the target file with root permissions, allowing the attacker to escalate privileges to root. HP released patches (e.g., HPSBUX9801-074) to address this issue.
Affected products
- HP HP-UX 11.0 and earlier
Timeline
- 1997-09-01: disclosed: Initial discovery and Bugtraq post by Leonid S. Knyshov
- 1997-09-01: advisory: NVD publication date