V-261336

Discussion

Without cryptographic integrity protections provided by FIPS 140-2/140-3 validated cryptographic algorithms, information can be viewed and altered by unauthorized users without detection. The system will attempt to use the first algorithm presented by the client that matches the server list. Listing the values "strongest to weakest" is a method to ensure the use of the strongest algorithm available to secure the SSH connection.

Check Content

Verify that the SSH server is configured to use only FIPS 140-2/140-3 validated key exchange algorithms with the following command:

     > sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*kexalgorithms'
     KexAlgorithms ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256
 
If "KexAlgorithms" does not contain the list of algorithms in the exact order, is commented out, missing, or conflicting results are returned, this is a finding.