5.2.12 Ensure only approved MAC algorithms are used

Information

MD5 and 96-bit MAC algorithms are considered weak and have been shown to increase exploitability in SSH downgrade attacks. Weak algorithms continue to have a great deal of attention as a weak spot that can be exploited with expanded computing power. An attacker that breaks the algorithm could take advantage of a MiTM position to decrypt the SSH tunnel and capture credentials and information

NOTE: Nessus has not performed this scan as manual review is required. Please view the results to ensure they are configured to site policy.

Solution

Edit the /etc/ssh/sshd_config file to set the parameter in accordance with site policy. The following includes all supported and accepted MACs: MACs [email protected],[email protected],[email protected],hmac-sha2-512,hmac-sha2-256,[email protected]

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-13, CSCv6|3.4

Plugin: Unix

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