1.8.2 Ensure GDM login banner is configured

Information

GDM is the GNOME Display Manager which handles graphical login for GNOME based systems.

Warning messages inform users who are attempting to login to the system of their legal status regarding the system and must include the name of the organization that owns the system and any monitoring policies that are in place.

Note: If a graphical login is not required, it should be removed to reduce the attack surface of the system.

Solution

Edit or create the file /etc/dconf/profile/gdm and add the following:

user-db:user
system-db:gdm
file-db:/usr/share/gdm/greeter-dconf-defaults

Edit or create the file /etc/dconf/db/gdm.d/ and add the following:

(This is typically /etc/dconf/db/gdm.d/01-banner-message )

[org/gnome/login-screen]
banner-message-enable=true
banner-message-text='<banner message>'

Example Banner Text:

'Authorized users only. All activity may be monitored and reported.'

Run the following command to update the system databases:

# dconf update

See Also

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