The Cisco ASA must be configured to implement replay-resistant authentication mechanisms for network access to privileged accounts.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-239913 | CASA-ND-000470 | SV-239913r960993_rule | CCI-001941 | medium |
| Description | ||||
| 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. | ||||
| STIG | Date | |||
| Cisco ASA NDM Security Technical Implementation Guide | 2025-05-19 | |||
Details
Check Text (C-239913r960993_chk)
Step 1: Verify that FIPS mode is enabled as shown in the example.
fips enable
Step 2: Verify only SSH is configured to only use FIPS-compliant ciphers and that Diffie-Hellman Group 14 is used for the key exchange as shown in the example below.
ssh version 2
ssh cipher encryption fips
ssh key-exchange group dh-group14-sha1
Note: The ASA only supports SSHv2.
If the ASA is not configured to implement replay-resistant authentication mechanisms for network access, this is a finding.
Fix Text (F-43105r666101_fix)
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