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V-274151

CAT II (Medium)

Amazon Linux 2023 must restrict the use of the "su" command.

Rule ID

SV-274151r1120441_rule

STIG

Amazon Linux 2023 Security Technical Implementation Guide

Version

V1R3

CCIs

CCI-002165

Discussion

The "su" program allows to run commands with a substitute user and group ID. It is commonly used to run commands as the root user. Limiting access to such commands is considered a good security practice.

Check Content

Verify Amazon Linux 2023 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 Text

Configure Amazon Linux 2023 to require users to be in the "wheel" group to run "su" command.

In file "/etc/pam.d/su", uncomment the following line:

"#auth required pam_wheel.so use_uid"

$ sudo sed '/^[[:space:]]*#[[:space:]]*auth[[:space:]]\+required[[:space:]]\+pam_wheel\.so[[:space:]]\+use_uid$/s/^[[:space:]]*#//' -i /etc/pam.d/su

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