The Red Hat Enterprise Linux operating system must be configured so that the SSH daemon is configured to only use Message Authentication Codes (MACs) employing FIPS 140-2 approved cryptographic hash algorithms.

From Red Hat Enterprise Linux 7 Security Technical Implementation Guide

Associated with: CCI-001453

SV-86877r3_rule The Red Hat Enterprise Linux operating system must be configured so that the SSH daemon is configured to only use Message Authentication Codes (MACs) employing FIPS 140-2 approved cryptographic hash algorithms.

Vulnerability discussion

DoD information systems are required to use FIPS 140-2 approved cryptographic hash functions. The only SSHv2 hash algorithm meeting this requirement is SHA.

Check content

Verify the SSH daemon is configured to only use MACs employing FIPS 140-2-approved ciphers. Note: If RHEL-07-021350 is a finding, this is automatically a finding as the system cannot implement FIPS 140-2-approved cryptographic algorithms and hashes. Check that the SSH daemon is configured to only use MACs employing FIPS 140-2-approved ciphers with the following command: # grep -i macs /etc/ssh/sshd_config MACs hmac-sha2-256,hmac-sha2-512 If any ciphers other than "hmac-sha2-256" or "hmac-sha2-512" are listed or the returned line is commented out, this is a finding.

Fix text

Edit the "/etc/ssh/sshd_config" file to uncomment or add the line for the "MACs" keyword and set its value to "hmac-sha2-256" and/or "hmac-sha2-512" (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-sha2-256,hmac-sha2-512 The SSH service must be restarted for changes to take effect.

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.