The Cisco switch must have all disabled switch ports assigned to an unused VLAN.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-220690 | CISC-L2-000210 | SV-220690r991946_rule | CCI-004891 | medium |
| Description | ||||
| It is possible that a disabled port that is assigned to a user or management VLAN becomes enabled by accident or by an attacker and as a result gains access to that VLAN as a member. | ||||
| STIG | Date | |||
| Cisco NX OS Switch L2S Security Technical Implementation Guide | 2024-08-22 | |||
Details
Check Text (C-220690r991946_chk)
Step 1: Review the switch configurations and examine all access switch ports. Each access switch port not in use should have membership to an inactive VLAN.
interface Ethernet1/81
shutdown
switchport access vlan 999
interface Ethernet1/82
shutdown
switchport access vlan 999
interface Ethernet1/83
shutdown
switchport access vlan 999
Step 2: Verify that traffic from the inactive VLAN is not allowed on any trunk links as shown in the example below:
interface Ethernet1/1
switchport mode trunk
switchport trunk allowed vlan 1-998,1000-4094
Note: Switch ports configured for 802.1x are exempt from this requirement.
If there are any access switch ports not in use and not in an inactive VLAN, this is a finding.
Fix Text (F-22394r539122_fix)
Assign all switch ports not in use to an inactive VLAN.
Step 1: Assign the disabled interfaces to an inactive VLAN.
SW1(config)# int e1/81-128
SW1(config-if-range)# switchport access vlan 999
SW1(config-if-range)# end
Step 2: Configure trunk links to not allow traffic from the inactive VLAN.
SW1(config-if)# switchport trunk allowed vlan except 999
SW1(config-if)# end