SLES-15-010270 - The SUSE operating system SSH daemon must be configured to only use Message Authentication Codes (MACs) employing FIPS 140-2 approved cryptographic hash algorithms.

Information

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Remote access (e.g., RDP) is access to DoD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash.

The system will attempt to use the first hash 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 hash available to secure the SSH connection.

Satisfies: SRG-OS-000125-GPOS-00065, SRG-OS-000394-GPOS-00174

Solution

Configure the SUSE operating system SSH daemon to only use MACs that employ FIPS 140-2 approved hashes.

Edit the '/etc/ssh/sshd_config' file to uncomment or add the line for the 'MACs' keyword and set its value to 'hmac-sha2-512' and/or 'hmac-sha2-256' (The file might be named differently or be in a different location):

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

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_SLES_15_V1R6_STIG.zip

Item Details

Category: ACCESS CONTROL, MAINTENANCE

References: 800-53|AC-17(2), 800-53|MA-4(6), 800-53|MA-4c., CAT|II, CCI|CCI-000877, CCI|CCI-001453, CCI|CCI-003123, Rule-ID|SV-234826r744126_rule, STIG-ID|SLES-15-010270, Vuln-ID|V-234826

Plugin: Unix

Control ID: 120bcca2e6453d530796cab544ff2d9be54c4ed889cd8da63beb1343f1764428