| Severity |
|
| Remote |
|
| Type |
| + |
Access restriction bypass |
|
| Description |
| + |
On Linux systems, sudo parses the /proc/[pid]/stat file to determine the device number of the process's tty (field 7). The fields in the file are space-delimited, but it is possible for the command name (field 2) to include spaces, which sudo does not account for. A user with sudo privileges can cause sudo to use a device number of the user's choosing by creating a symbolic link from the sudo binary to a name that contains a space, followed by a number. |
| + |
This may allow a user to be able to bypass the "tty_ticket" constraints. In order for this to succeed there must exist on the machine a terminal device that the user has previously authenticated themselves on via sudo within the last time stamp timeout (5 minutes by default). |
|
| References |
| + |
https://www.sudo.ws/alerts/linux_tty.html |
| + |
http://www.openwall.com/lists/oss-security/2017/05/30/16 |
| + |
https://www.sudo.ws/repos/sudo/raw-rev/b5460cbbb11b |
|
| Notes |
| + |
If SELinux is enabled on the system and sudo was built with SELinux support, it is possible for a user with sudo privileges to overwrite an arbitrary file. This can be escalated to full root access by rewriting a trusted file such as /etc/shadow or event /etc/sudoers. |
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