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Remote X connections for interactive users must be encrypted.


Overview

Finding ID Version Rule ID IA Controls Severity
V-75853 UBTU-16-030400 SV-90533r2_rule High
Description
Open X displays allow an attacker to capture keystrokes and execute commands remotely.
STIG Date
Canonical Ubuntu 16.04 Security Technical Implementation Guide 2020-05-29

Details

Check Text ( C-75541r1_chk )
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 (F-82483r2_fix)
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