The Cisco switch must be configured to implement replay-resistant authentication mechanisms for network access to privileged accounts.

A replay attack may enable an unauthorized user to gain access to the application. Authentication sessions between the authenticator and the application validating the user credentials must not be vulnerable to a replay attack.

An authentication process resists replay attacks if it is impractical to achieve a successful authentication by recording and replaying a previous authentication message.

Review the Cisco router configuration to verify it is compliant with this requirement as shown in the example below.

SSH Example

ssh macs hmac-sha2-256 hmac-sha2-512

NOTE: Using "fips mode enable" to enable all FIPS protocols disables TACACS+ and RADIUS, which is required for authentication server requirements. It is recommended to enable FIPS-validated protocols manually and keep FIPS mode disabled.

If the Cisco router is not configured to use FIPS-validated HMAC to protect the integrity of remote maintenance sessions, this is a finding.

Configure SSH to use FIPS-validated HMAC for remote maintenance sessions as shown in the following example:

SSH Example

R1(config)#ssh macs hmac-sha2-256 hmac-sha2-512