All port groups must not be configured to VLAN 4095 unless Virtual Guest Tagging (VGT) is required.

From VMware vSphere vCenter Server Version 6 Security Technical Implementation Guide

Part of SRG-APP-000516

Associated with: CCI-000366

SV-78465r1_rule All port groups must not be configured to VLAN 4095 unless Virtual Guest Tagging (VGT) is required.

Vulnerability discussion

When a port group is set to VLAN 4095, this activates VGT mode. In this mode, the vSwitch passes all network frames to the guest VM without modifying the VLAN tags, leaving it up to the guest to deal with them. VLAN 4095 should be used only if the guest has been specifically configured to manage VLAN tags itself. If VGT is enabled inappropriately, it might cause denial-of-service or allow a guest VM to interact with traffic on an unauthorized VLAN.

Check content

From the vSphere Web Client go to Networking >> Select a distributed port group >> Manage >> Settings >> Policies. Review the port group VLAN tags and verify they are not set to 4095. or From a PowerCLI command prompt while connected to the vCenter server run the following command: Get-VDPortgroup | select Name, VlanConfiguration If any port group is configured with VLAN 4095 and is not documented as a needed exception, this is a finding.

Fix text

To change the VLAN ID of distributed virtual port groups do the following: From the vSphere Web Client go to Networking >> Select a distributed port group >> Manage >> Settings >> Policies. Click Edit and under the VLAN section change the VLAN ID to not be 4095 and click OK. or From a PowerCLI command prompt while connected to the vCenter server run the following command: Get-VDPortgroup "portgroup name" | Set-VDVlanConfiguration -VlanId "New VLAN#"

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.

Powered by sagemincer