The Cisco router must be configured to have all inactive interfaces disabled.

An inactive interface is rarely monitored or controlled and may expose a network to an undetected attack on that interface. Unauthorized personnel with access to the communication facility could gain access to a router by connecting to a configured interface that is not in use.

If an interface is no longer used, the configuration must be deleted and the interface disabled. For sub-interfaces, delete sub-interfaces that are on inactive interfaces and delete sub-interfaces that are themselves inactive. If the sub-interface is no longer necessary for authorized communications, it must be deleted.

Review the router configuration and verify that inactive interfaces have been disabled as shown below.

interface GigabitEthernet0/0/1/0 shutdown ! interface GigabitEthernet0/0/1/1 shutdown

If an interface is not being used but is configured or enabled, this is a finding.

Disable all inactive interfaces as shown below.

R4(config)#interface GigabitEthernet3 R4(config-if)#shutdown R4(config)#interface GigabitEthernet4 R4(config-if)#shutdown