Title

RHEL 9 SSH daemon must perform strict mode checking of home directory configuration files. (Cat II impact)

Discussion

If other users have access to modify user-specific SSH configuration files, they may be able to log into the system as another user.

Check Content

Verify the SSH daemon performs strict mode checking of home directory configuration files with the following command: $ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*strictmodes' StrictModes yes If the "StrictModes" keyword is set to "no", the returned line is commented out, or no output is returned, this is a finding.

Fix Text

Configure the SSH daemon to perform strict mode checking of home directory configuration files. Add the following line in "/etc/ssh/sshd_config", or uncomment the line and set the value to "yes": StrictModes yes The SSH service must be restarted for changes to take effect: $ sudo systemctl restart sshd.service

Additional Identifiers

Rule ID: SV-258008r952212_rule

Vulnerability ID: V-258008

Group Title: SRG-OS-000480-GPOS-00227

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.