The Cisco switch must have all disabled switch ports assigned to an unused VLAN.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-220667 | CISC-L2-000210 | SV-220667r991904_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 IOS XE Switch L2S Security Technical Implementation Guide | 2025-05-19 | |||
Details
Check Text (C-220667r991904_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 GigabitEthernet0/0
switchport access vlan 999
shutdown
!
interface GigabitEthernet0/1
switchport access vlan 999
shutdown
…
…
…
interface GigabitEthernet0/9
switchport access vlan 999
shutdown
Step 2: Verify that traffic from the inactive VLAN is not allowed on any trunk links as shown in the example below:
interface GigabitEthernet1/1
switchport trunk allowed vlan 1-998,1000-4094
switchport trunk encapsulation dot1q
switchport mode trunk
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-22371r507550_fix)
Assign all switch ports not in use to an inactive VLAN.
Step 1: Assign the disabled interfaces to an inactive VLAN.
SW3(config)#int range g0/0 – 9
SW3(config-if-range)# switchport access vlan 999
Step 2: Configure trunk links to not allow traffic from the inactive VLAN.
SW3(config)#int g1/1
SW3(config-if)#switchport trunk allowed vlan except 999