STIGQter STIGQter: STIG Summary: Canonical Ubuntu 18.04 LTS Security Technical Implementation Guide Version: 2 Release: 3 Benchmark Date: 23 Apr 2021:

The Ubuntu operating system must be configured so that remote X connections are disabled, unless to fulfill documented and validated mission requirements.

DISA Rule

SV-233779r610963_rule

Vulnerability Number

V-233779

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

UBTU-18-010418

Severity

CAT II

CCI(s)

Weight

10

Fix Recommendation

Edit the "/etc/ssh/sshd_config" file to uncomment or add the line for the "X11Forwarding" keyword and set its value to "no" (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor):

X11Forwarding no

The SSH service must be restarted for changes to take effect:

$ sudo systemctl restart sshd

Check Contents

Verify that X11Forwarding is disabled with the following command:

# grep -i x11forwarding /etc/ssh/sshd_config | grep -v "^#"

X11Forwarding no

If the "X11Forwarding" keyword is set to "yes" and is not documented with the Information System Security Officer (ISSO) as an operational requirement or is missing, this is a finding.

Vulnerability Number

V-233779

Documentable

False

Rule Version

UBTU-18-010418

Severity Override Guidance

Verify that X11Forwarding is disabled with the following command:

# grep -i x11forwarding /etc/ssh/sshd_config | grep -v "^#"

X11Forwarding no

If the "X11Forwarding" keyword is set to "yes" and is not documented with the Information System Security Officer (ISSO) as an operational requirement or is missing, this is a finding.

Check Content Reference

M

Target Key

4055

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