Title

The network devices must be configured to timeout after 60 seconds or less for incomplete or broken SSH sessions. (Cat II impact)

Discussion

An attacker may attempt to connect to the device using SSH by guessing the authentication method, encryption algorithm, and keys. Limiting the amount of time allowed for authenticating and negotiating the SSH session reduces the window of opportunity for the malicious user attempting to make a connection to the network device.

Check Content

Review the configuration and verify the timeout is set for 60 seconds or less. The SSH service terminates the connection if protocol negotiation (that includes user authentication) is not complete within this timeout period. If the device is not configured to drop broken SSH sessions after 60 seconds, this is a finding.

Fix Text

Configure the network devices so it will require a secure shell timeout of 60 seconds or less.

Additional Identifiers

Rule ID: SV-5612r4_rule

Vulnerability ID: V-5612

Group Title: SSH session timeout is not 60 seconds or less.

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.