The Cisco switch must have all disabled switch ports assigned to an unused VLAN.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-220690 | SRG-NET-000512-L2S-000007 | CISC-L2-000210 | SV-220690r991946_rule | 2024-08-22 | 3 |
| 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. |
| ℹ️ Check |
|---|
| 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 |
|---|
| 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 |