The Arista MLS layer 2 switch must have the native VLAN assigned to an ID other than the default VLAN for all 802.1q trunk links.
An XCCDF Rule
Description
<VulnDiscussion>VLAN hopping can be initiated by an attacker who has access to a switch port belonging to the same VLAN as the native VLAN of the trunk link connecting to another switch that the victim is connected to. If the attacker knows the victim’s MAC address, it can forge a frame with two 802.1q tags and a layer 2 header with the destination address of the victim. Since the frame will ingress the switch from a port belonging to its native VLAN, the trunk port connecting to the victim’s switch will simply remove the outer tag because native VLAN traffic is to be untagged. The switch will forward the frame on to the trunk link unaware of the inner tag with a VLAN ID of which the victim’s switch port is a member.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-255985r882297_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
Configure the interface trunk ports for the unique Native VLAN ID and configure the VLAN allowed by using the following commands:
switch(config)#interface Ethernet10
switch(config-eth10)#description #STIG VLAN 1 Pruning
switch(config-eth10)# switchport trunk native vlan 1000
switch(config-eth10)#switchport trunk allowed vlan 2-4094