Details

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.

Techniques used to address this include protocols using nonces (e.g., numbers generated for a specific one-time use) or challenges (e.g., TLS, WS_Security). Additional techniques include time-synchronous or challenge-response one-time authenticators.

Solution

Step 1: Enable FIPS mode via the fips enable command.

Step 2: Configure SSH to only use FIPS-compliant ciphers and Diffie-Hellman Group 14 for the key exchange.

ASA(config)# ssh cipher encryption fips
ASA(config)# ssh key-exchange group dh-group14-sha

Supportive Information

The following resource is also helpful.

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

This security hardening control applies to the following category of controls within NIST 800-53: Identification and Authentication.This control applies to the following type of system Cisco.

References

• 800-53|IA-2(8)
• CAT|II
• CCI|CCI-001941
• Rule-ID|SV-239913r666102_rule
• STIG-ID|CASA-ND-000470
• Vuln-ID|V-239913

Source

• Tenable.com/audits