The Ubuntu operating system must display the Standard Mandatory DoD Notice and Consent Banner before granting local or remote access to the system via a ssh logon and the user must acknowledge the usage conditions and take explicit actions to log on for further access.

From Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide

Part of SRG-OS-000023-GPOS-00006

Associated with: CCI-000048

SV-90505r3_rule The Ubuntu operating system must display the Standard Mandatory DoD Notice and Consent Banner before granting local or remote access to the system via a ssh logon and the user must acknowledge the usage conditions and take explicit actions to log on for further access.

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 Ubuntu 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 Ubuntu 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 content

Verify the Ubuntu operating system displays the Standard Mandatory DoD Notice and Consent Banner before granting access to the Ubuntu operating system via a ssh logon. Check that the Ubuntu operating system displays the Standard Mandatory DoD Notice and Consent Banner before granting access to the Ubuntu operating system via a ssh logon with the following command: # grep -i banner /etc/ssh/sshd_config Banner=/etc/issue.net The command will return the banner option along with the name of the file that contains the ssh banner. If the line is commented out this is a finding. Check the specified banner file to check that it matches the Standard Mandatory DoD Notice and Consent Banner exactly: “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.” If the banner text does not match the Standard Mandatory DoD Notice and Consent Banner exactly, this is a finding.

Fix text

Configure the Ubuntu operating system to display the Standard Mandatory DoD Notice and Consent Banner before granting access to the system via SSH logon. Edit the SSH daemon configuration "/etc/ssh/sshd_config" file. Uncomment the banner keyword and configure it to point to the file that contains the correct banner. An example of this configure is below: Banner=/etc/issue.net Either create the file containing the banner, or replace the text in the file with the Standard Mandatory DoD Notice and Consent Banner. The DoD required text is: "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." The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: # sudo systemctl restart sshd.service

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