Title

The vCenter Server must set the distributed port group MAC Address Change policy to reject. (Cat II impact)

Discussion

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 and will affect applications that require a specific MAC address for licensing.

Check Content

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

From the vSphere 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

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.