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 configure the SSH daemon to only use Message Authentication Codes (MACs) employing FIPS 140-2 approved cryptographic hash algorithms to protect the integrity of nonlocal maintenance and diagnostic communications.

DISA Rule

SV-219312r610963_rule

Vulnerability Number

V-219312

Group Title

SRG-OS-000250-GPOS-00093

Rule Version

UBTU-18-010417

Severity

CAT II

CCI(s)

• CCI-002890 - The information system implements cryptographic mechanisms to protect the integrity of nonlocal maintenance and diagnostic communications.
• CCI-003123 - The information system implements cryptographic mechanisms to protect the confidentiality of nonlocal maintenance and diagnostic communications.
• CCI-001453 - The information system implements cryptographic mechanisms to protect the integrity of remote access sessions.

Weight

10

Fix Recommendation

Configure the Ubuntu operating system to allow the SSH daemon to only use Message Authentication Codes (MACs) that employ FIPS 140-2 approved ciphers.

Add the following line (or modify the line to have the required value) to the "/etc/ssh/sshd_config" file (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):

MACs hmac-sha2-512,hmac-sha2-256

In order for the changes to take effect, reload the SSH daemon.

# sudo systemctl reload sshd.service

Check Contents

Verify the Ubuntu operating system configures the SSH daemon to only use Message Authentication Codes (MACs) that employ FIPS 140-2 approved ciphers.

Check that the SSH daemon is configured to only use MACs that employ FIPS 140-2 approved ciphers with the following command:

# sudo grep -i macs /etc/ssh/sshd_config

MACs hmac-sha2-512,hmac-sha2-256

If any ciphers other than "hmac-sha2-512" or "hmac-sha2-256" are listed, the order differs from the example above, or the returned line is commented out, this is a finding.

Vulnerability Number

V-219312

Documentable

False

Rule Version

UBTU-18-010417

Severity Override Guidance

Verify the Ubuntu operating system configures the SSH daemon to only use Message Authentication Codes (MACs) that employ FIPS 140-2 approved ciphers.

Check that the SSH daemon is configured to only use MACs that employ FIPS 140-2 approved ciphers with the following command:

# sudo grep -i macs /etc/ssh/sshd_config

MACs hmac-sha2-512,hmac-sha2-256

If any ciphers other than "hmac-sha2-512" or "hmac-sha2-256" are listed, the order differs from the example above, or the returned line is commented out, this is a finding.

Check Content Reference

M

Target Key

4055

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