Details

A disabled port that is assigned to a user or management VLAN may become enabled by accident or by an attacker and as a result may gain access to that VLAN as a member.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

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

Supportive Information

The following resource is also helpful.

• https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS_Switch_Y21M07_STIG.zip

This security hardening control applies to the following category of controls within NIST 800-53: Configuration Management.This control applies to the following type of system Cisco.

References

• 800-53|CM-6b.
• CAT|II
• CCI|CCI-000366
• Rule-ID|SV-220641r539671_rule
• STIG-ID|CISC-L2-000210
• STIG-Legacy|SV-110253
• STIG-Legacy|V-101149
• Vuln-ID|V-220641

Source

• Tenable.com/audits