5.3.7 Ensure access to the su command is restricted

Information

The su command allows a user to run a command or shell as another user. The program has been superseded by sudo which allows for more granular control over privileged access. Normally, the su command can be executed by any user. By uncommenting the pam_wheel.so statement in /etc/pam.d/su the su command will only allow users in a specific groups to execute su This group should be empty to reinforce the use of sudo for privileged access.

Restricting the use of su and using sudo in its place, provides system administrators better control of the escalation of user privileges to execute privileged commands. The sudo utility also provides a better logging and audit mechanism, as it can log each command executed via sudo whereas su can only record that a user executed the su program.

Solution

Create an empty group that will be specified for use of the su command. The group should be named according to site policy.

Example:

# groupadd sugroup

Add the following line to the /etc/pam.d/su file, specifying the empty group:

auth required pam_wheel.so use_uid group=sugroup

See Also

https://workbench.cisecurity.org/files/3796

Item Details

Category: ACCESS CONTROL, MEDIA PROTECTION

References: 800-53|AC-3, 800-53|AC-5, 800-53|AC-6, 800-53|MP-2, CSCv7|5.1

Plugin: Unix

Control ID: 7bad103a625a13f65d4f5c38199ce93ca41fe14f20bf9d54d3fd2a689566f8e3