The vCenter Server must set the distributed port group Media Access Control (MAC) Address Change policy to "Reject".

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-258936	VCSA-80-000269	SV-258936r961863_rule		Medium

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 virtual machines from changing their effective MAC address and will affect applications that require this functionality. This will also affect how a layer 2 bridge will operate and will 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 virtual machines from changing their effective MAC address and will affect applications that require this functionality. This will also affect how a layer 2 bridge will operate and will affect applications that require a specific MAC address for licensing.

STIG	Date
VMware vSphere 8.0 vCenter Security Technical Implementation Guide	2024-07-11

Details

Check Text ( C-62676r934464_chk )
If distributed switches are not used, this is not applicable. From the vSphere 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-62676r934464_chk )

If distributed switches are not used, this is not applicable.

From the vSphere 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-62585r934465_fix)
From the vSphere Client, go to "Networking". Select a distributed switch >> Select a port group >> Configure >> Settings >> Policies. Click "Edit". Click the "Security" tab. 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-62585r934465_fix)

From the vSphere Client, go to "Networking".

Select a distributed switch >> Select a port group >> Configure >> Settings >> Policies.

Click "Edit".

Click the "Security" tab.

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