The virtual switch MAC Address Change policy must be set to reject on the ESXi host.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-239314	ESXI-67-000060	SV-239314r674871_rule		High

Description

If the virtual machine operating system changes the MAC address, it can send frames with an impersonated source MAC address at any time. This allows it to stage malicious attacks on the devices in a network by impersonating a network adaptor authorized by the receiving network. This will prevent VMs from changing their effective MAC address. It will affect applications that require this functionality, how a layer 2 bridge will operate, and applications that require a specific MAC address for licensing. Reject MAC Changes can be set at the vSwitch and/or the Portgroup level. Switch-level settings can be overridden at the Portgroup level.

STIG	Date
VMware vSphere 6.7 ESXi Security Technical Implementation Guide	2022-01-05

Details

Check Text ( C-42547r674869_chk )

From the vSphere Client, go to Configure >> Networking >> Virtual Switches. View the properties on each virtual switch and port group and verify "MAC Address Changes" is set to reject. or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: Get-VirtualSwitch | Get-SecurityPolicy Get-VirtualPortGroup | Get-SecurityPolicy If the "MAC Address Changes" policy is set to accept (or true, via PowerCLI), this is a finding.

Fix Text (F-42506r674870_fix)

From the vSphere Client, go to Configure >> Networking >> Virtual Switches. For each virtual switch and port group, click Edit settings (dots) and change "MAC Address Changes" to reject. or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: Get-VirtualSwitch | Get-SecurityPolicy | Set-SecurityPolicy -MacChanges $false Get-VirtualPortGroup | Get-SecurityPolicy | Set-SecurityPolicy -MacChangesInherited $true