Title

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. (Cat II impact)

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. 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. # sudo service sshd restart

Additional Identifiers

Rule ID: SV-217995r505923_rule

Vulnerability ID: V-217995

Group Title: SRG-OS-000250

Expert Comments

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