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V-215294

CAT II (Medium)

AIX SSH daemon must be configured to only use Message Authentication Codes (MACs) employing FIPS 140-2 approved cryptographic hash algorithms.

Rule ID

SV-215294r991589_rule

STIG

IBM AIX 7.x Security Technical Implementation Guide

Version

V3R2

CCIs

CCI-000366

Discussion

DoD information systems are required to use FIPS 140-2 approved cryptographic hash functions.

Check Content

Check the SSH daemon configuration for allowed MACs by running the following command: 
# grep -i macs /etc/ssh/sshd_config | grep -v '^#' 
MACs hmac-sha1,hmac-sha1-96,hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96

If no lines are returned, or the returned MAC list contains any MAC that is not FIPS 140-2 approved, this is a finding.

Fix Text

Edit the "/etc/ssh/sshd_config" file and add/edit the following line to contain FIPS 140-2 approved ciphers:
MACs hmac-sha1,hmac-sha1-96,hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96

Restart SSH daemon:
# stopsrc -s sshd
# startsrc -s sshd

Note: If the "MACs" configuration contains any ciphers that are not FIPS 140-2 approved, they should be removed from the configuration file.