VMware vSphere 7.0 vCenter STIG Version Comparison

There are 4 differences between versions v1 r1 (March 7, 2023) (the "left" version) and v1 r3 (Jan. 24, 2024) (the "right" version).

Check VCSA-70-000268 was changed between these two versions. Green, underlined text was added, red, struck-out text was removed.

The regular view of the left check and right check may be easier to read.

Title

The vCenter Server must set the distributed port group Forged Transmits policy to "Reject".

Check Content

If distributed switches are not used, this is not applicable. From the vSphere Client, go to "Networking". Select a distributed switch and then select a port group. Select Configure >> Settings >> Policies. Verify "Forged Transmits" 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 "Forged Transmits" policy is set to accept for a nonuplink port, and is not documented as an exception, this is a finding.

Discussion

If the virtual machine operating system changes the Media Access Control (MAC) address, the operating system can send frames with an impersonated source MAC address at any time. This allows an operating system to stage malicious attacks on the devices in a network by impersonating a network adaptor authorized by the receiving network. When the "Forged Transmits" option is set to "Accept", ESXi does not compare source and effective MAC addresses. To protect against MAC impersonation, set the "Forged Transmits" option to "Reject". The host compares the source MAC address being transmitted by the guest operating system with the effective MAC address for its virtual machine adapter to determine if they match. If the addresses do not match, the ESXi host drops the packet.

Fix

From the vSphere Client, go to "Networking". Select a distributed switch and then select a port group. Select Configure >> Settings >> Policies. Click "Edit". Click the "Security" tab. Set "Forged Transmits" 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 -ForgedTransmits $false Get-VDPortgroup | ?{$_.IsUplink -eq $false} | Get-VDSecurityPolicy | Set-VDSecurityPolicy -ForgedTransmits $false