Vulnerability Discussion

The "su" program provides a "switch user" capability. It is commonly used to become root but can be used to switch to any user.

Limiting access to such commands is considered a good security practice.

Satisfies: SRG-OS-000109-GPOS-00056, SRG-OS-000312-GPOS-00124, SRG-OS-000312-GPOS-00122, SRG-OS-000312-GPOS-00123

Check

Verify that AlmaLinux OS 9 requires uses to be members of the "wheel" group with the following command:

$ grep pam_wheel /etc/pam.d/su

auth required pam_wheel.so use_uid

If a line for "pam_wheel.so" does not exist, or is commented out, this is a finding.

Fix

Configure AlmaLinux OS 9 to require users to be in the "wheel" group to run "su" command.

In the "/etc/pam.d/su" file, uncomment the "pam_wheel.so" line as per the instructions in the file:

# Uncomment the following line to require a user to be in the "wheel" group.
#auth required pam_wheel.so use_uid

If necessary, create a "wheel" group and add administrative users to the group.