Vulnerability Discussion

Display of a standardized and approved use notification before granting access to the Ubuntu operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance.

System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist.

The banner must be formatted in accordance with applicable DoD policy. Use the following verbiage for operating systems that can accommodate banners of 1300 characters:

"You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.

By using this IS (which includes any device attached to this IS), you consent to the following conditions:

-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.

-At any time, the USG may inspect and seize data stored on this IS.

-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.

-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.

-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

Use the following verbiage for operating systems that have severe limitations on the number of characters that can be displayed in the banner:

"I've read & consent to terms in IS user agreem't."

Check

Verify the Ubuntu operating system is configured to display the Standard Mandatory DoD Notice and Consent Banner before granting access to the operating system via a graphical user logon.

Note: If the system does not have a graphical user interface installed, this requirement is Not Applicable.

Check that the operating banner message for the graphical user logon is enabled with the following command:

$ grep ^banner-message-enable /etc/gdm3/greeter.dconf-defaults

banner-message-enable=true

If the line is commented out or set to "false", this is a finding.

Fix

Edit the "/etc/gdm3/greeter.dconf-defaults" file.

Look for the "banner-message-enable" parameter under the "[org/gnome/login-screen]" section and uncomment it (remove the leading "#" characters):

Note: The lines are all near the bottom of the file but not adjacent to each other.

[org/gnome/login-screen]

banner-message-enable=true

Update the GDM with the new configuration:

$ sudo dconf update
$ sudo systemctl restart gdm3