The SetX11Keyboard function in systemd, when PolicyKit Local Authority (PKLA) is used to change the group permissions on the X Keyboard Extension (XKB) layouts description, allows local users in the group to modify the Xorg X11 Server configuration file and possibly gain privileges via vectors involving special and control characters.
Weakness
During installation, installed file permissions are set to allow anyone to modify those files.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| Systemd |
Systemd_project |
* |
194 (excluding) |
Potential Mitigations
- Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
- Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
References