The Ubuntu operating system must not permit direct logons to the root account using remote access via SSH.

From Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide

Associated with: CCI-000366

SV-90507r2_rule The Ubuntu operating system must not permit direct logons to the root account using remote access via SSH.

Vulnerability discussion

Even though the communications channel may be encrypted, an additional layer of security is gained by extending the policy of not logging on directly as root. In addition, logging on with a user-specific account provides individual accountability of actions performed on the system.

Check content

Verify remote access using SSH prevents users from logging on directly as "root". Check that SSH prevents users from logging on directly as "root" with the following command: # grep PermitRootLogin /etc/ssh/sshd_config PermitRootLogin no If the "PermitRootLogin" keyword is set to "yes", is missing, or is commented out, this is a finding.

Fix text

Configure the Ubuntu operating system to stop users from logging on remotely as the "root" user via SSH. Edit the appropriate "/etc/ssh/sshd_config" file to uncomment or add the line for the "PermitRootLogin" keyword and set its value to "no": PermitRootLogin no 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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