STIGQter STIGQter: STIG Summary: Canonical Ubuntu 24.04 LTS Security Technical Implementation Guide Version: 1 Release: 6 Benchmark Date: 01 Jul 2026:

Ubuntu 24.04 LTS SSH client must be configured to use only Message Authentication Codes (MACs) employing FIPS 140-3 validated cryptographic hash algorithms.

DISA Rule

SV-270671r1155244_rule

Vulnerability Number

V-270671

Group Title

SRG-OS-000250-GPOS-00093

Rule Version

UBTU-24-100860

Severity

CAT II

CCI(s)

Weight

10

Fix Recommendation

Configure the Ubuntu 24.04 LTS SSH client to use only MACs employing FIPS 140-3 approved algorithms by updating the "/etc/ssh/ssh_config" file with the following line:

MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256

Restart the "ssh" service for changes to take effect:

$ sudo systemctl restart ssh

Check Contents

Verify the SSH client is configured to only use MACs employing FIPS 140-3 approved algorithms with the following command:

$ sudo grep -ir macs /etc/ssh/ssh_config*
MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256

If any MACs other than "hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256" are listed, or the returned line is commented out, this is a finding.

Vulnerability Number

V-270671

Documentable

False

Rule Version

UBTU-24-100860

Severity Override Guidance

Verify the SSH client is configured to only use MACs employing FIPS 140-3 approved algorithms with the following command:

$ sudo grep -ir macs /etc/ssh/ssh_config*
MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256

If any MACs other than "hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256" are listed, or the returned line is commented out, this is a finding.

Check Content Reference

M

Target Key

5673