Vulnerability GHSA-w9q3-g4p5-5q2r

Summary

Users with limited sudo privileges (e.g. execution of a single command) can list sudo privileges of other users using the -U flag. This doesn't happen with the original sudo.

PoC

The initial test has been done in a container running Ubuntu 24.04 and installing oxidizr, running sudo-rs 0.2.2.

A user (bob) has been added with only ps command executable through sudo:

root    ALL=(ALL:ALL) ALL
bob     ALL=(ALL:ALL) /usr/bin/ps

The user is not able to read the /etc/sudoers file and running sudo -l -Uroot with original sudo (version 1.9.15p5) causes the following error:

Sorry, user bob is not allowed to execute 'list' as root on 43d4aed3cdbd.

The same command with sudo-rs is run without denying the execution:

User root may run the following commands on 43d4aed3cdbd:
    (ALL : ALL) ALL

The same happens for other non-root users:

bob@43d4aed3cdbd:~$ sudo -l -Ufoo
User foo may run the following commands on 43d4aed3cdbd:
    (ALL : ALL) /usr/bin/whoami

The behavior has been also been observed for version 0.2.5.

Impact

Users with limited sudo privileges can enumerate the sudoers file, revealing sensitive information about other users' permissions. Attackers can collect information that can be used to more targeted attacks.

Systems where users either do not have sudo privileges or have the ability to run all commands as root through sudo (the default configuration on most systems) are not affected by this advisory.

Credits

This issue was identified by Sonia Zorba.