Vulnerability Discussion

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

With a UMASK of 077, files will be created with 0600 permissions (owner read/write only) and directories will have 0700 permissions (owner read/write/execute only).

Check

Verify that the "pam_umask" module is enabled with the following command:

$ grep -i umask /etc/pam.d/*

/etc/pam.d/postlogin:session optional pam_umask.so silent umask=0022

If a "pam_umask.so" line is not returned, this is a finding.

If the "umask" setting is set to anything other than "0077", this is a finding.

Note: If the "umask" setting is not found, it will use the default UMASK entry in /etc/login.defs.

Fix

Configure AlmaLinux OS 9 to define default permissions for all authenticated users so the user can only read and modify their own files.

Add or edit the following line at the top of /etc/pam.d/postlogin:

session optional pam_umask.so silent