The network device must 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.

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.

Review the configuration and verify SSH Version 1 is not being used for administrative access.

If the device is using an SSHv1 session, this is a finding.

Configure the network device to use SSH Version 2.