The vCenter Server for Windows must set the distributed port group MAC Address Change policy to reject.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-94739	VCWN-65-000014	SV-104569r1_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. This will also affect how a layer 2 bridge will operate. This will also affect applications that require a specific MAC address for licensing.

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. This will also affect how a layer 2 bridge will operate. This will also affect applications that require a specific MAC address for licensing.

STIG	Date
VMware vSphere 6.5 vCenter Server for Windows Security Technical Implementation Guide	2019-05-22

Details

Check Text ( C-93929r1_chk )
From the vSphere Web Client go to Networking >> Select a distributed switch >> Select a port group >> Configure >> Settings >> Policies Verify "MAC Address Changes" is set to reject. or From a PowerCLI command prompt while connected to the vCenter server run the following commands: Get-VDSwitch \| Get-VDSecurityPolicy Get-VDPortgroup \| ?{$_.IsUplink -eq $false} \| Get-VDSecurityPolicy If the "MAC Address Changes" policy is set to accept, this is a finding.

Check Text ( C-93929r1_chk )

From the vSphere Web Client go to Networking >> Select a distributed switch >> Select a port group >> Configure >> Settings >> Policies

Verify "MAC Address Changes" is set to reject.

or

From a PowerCLI command prompt while connected to the vCenter server run the following commands:
Get-VDSwitch | Get-VDSecurityPolicy
Get-VDPortgroup | ?{$_.IsUplink -eq $false} | Get-VDSecurityPolicy

If the "MAC Address Changes" policy is set to accept, this is a finding.

Fix Text (F-100857r1_fix)
From the vSphere Web Client go to Networking >> Select a distributed switch >> Select a port group >> Configure >> Settings >> Policies >> Edit >> Security. Set "MAC Address Changes" to reject. Click "OK". or From a PowerCLI command prompt while connected to the vCenter server run the following commands: Get-VDSwitch \| Get-VDSecurityPolicy \| Set-VDSecurityPolicy -MacChanges $false Get-VDPortgroup \| ?{$_.IsUplink -eq $false} \| Get-VDSecurityPolicy \| Set-VDSecurityPolicy -MacChanges $false

Fix Text (F-100857r1_fix)

From the vSphere Web Client go to Networking >> Select a distributed switch >> Select a port group >> Configure >> Settings >> Policies >> Edit >> Security. Set "MAC Address Changes" to reject. Click "OK".

or

From a PowerCLI command prompt while connected to the vCenter server run the following commands:
Get-VDSwitch | Get-VDSecurityPolicy | Set-VDSecurityPolicy -MacChanges $false
Get-VDPortgroup | ?{$_.IsUplink -eq $false} | Get-VDSecurityPolicy | Set-VDSecurityPolicy -MacChanges $false