Vulnerability Discussion

Setting the most restrictive default permissions ensures that when new accounts are created, they do not have unnecessary access.

Satisfies: SRG-OS-000480-GPOS-00228, SRG-OS-000480-GPOS-00230

Check

Verify Amazon Linux 2023 defines default permissions for all authenticated users in such a way that the user can only read and modify their own files with the following command:

Note: If the value of the "UMASK" parameter is set to "000" in "/etc/login.defs" file, the Severity is raised to a CAT I.

# grep -i umask /etc/login.defs
UMASK 077

If the value for the "UMASK" parameter is not "077", or the "UMASK" parameter is missing or is commented out, this is a finding.

Fix

Configure Amazon Linux 2023 to define default permissions for all authenticated users in such a way that the user can only read and modify their own files.

Add or edit the lines for the "UMASK" parameter in the "/etc/login.defs" file to "077":

UMASK 077