The Arista MLS layer 2 switch must have all disabled switch ports assigned to an unused VLAN.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-255980	ARST-L2-000170	SV-255980r882282_rule		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
Arista MLS EOS 4.2x L2S Security Technical Implementation Guide	2023-01-11

Details

Check Text ( C-59656r882280_chk )

Step 1: Review the switch configuration and examine all access switch ports. Verify the unused port is configured to be intentionally shut down and assigned to an inactive VLAN. switch(config)#sh run int eth8 interface Ethernet8 description PORT IS INTENTIONALLY SHUTDOWN switchport access vlan 999 shutdown switch(config)# Step 2: Verify traffic from the inactive VLAN is not allowed on any trunk links as shown in the example below: switch(config)#sh run int eth9 interface Ethernet9 switchport trunk native vlan 1000 switchport trunk allowed vlan 2-998, 1001-4094 switchport mode trunk switch(config)# If any access switch ports are not in use and not in an inactive shutdown, this is a finding. Note: Switch ports configured for 802.1x are exempt from this requirement.

Fix Text (F-59599r882281_fix)

Configure all Arista MLS switch ports not in use to be shut down and assigned to an unused VLAN. Step 1: Configure all unused ports to be shut down and assigned to an unused VLAN. switch(config)#interface ethernet 9 switch(config-eth9)#shutdown switch(config-eth9)# description this port is intentionally shutdown switch(config-eth9)# switchport access vlan 999 Step 2: Configure any trunk links to exclude the unused VLAN. switch(config)# interface ethernet 10 switch(config-eth10)# switchport trunk native vlan 1000 switch(config-eth9)# switchport trunk allowed vlan 2-998, 1001-4094 switch(config-eth9)# switchport mode trunk