Remote X connections for interactive users must be encrypted.

From Canonical Ubuntu 16.04 Security Technical Implementation Guide

Associated with: CCI-000366

SV-90533r2_rule Remote X connections for interactive users must be encrypted.

Vulnerability discussion

Open X displays allow an attacker to capture keystrokes and execute commands remotely.

Check content

Verify remote X connections for interactive users are encrypted. Check that remote X connections are encrypted with the following command: # grep -i x11forwarding /etc/ssh/sshd_config X11Forwarding yes If the "X11Forwarding" keyword is set to "no", is missing, or is commented out, this is a finding.

Fix text

Configure SSH to encrypt connections for interactive users. Edit the "/etc/ssh/sshd_config" file to uncomment or add the line for the "X11Forwarding" keyword and set its value to "yes": X11Forwarding yes 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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