ESXI-80-000216 The ESXi host must configure virtual switch security policies to reject forged transmits.

Information

If the virtual machine (VM) 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.

This means the virtual switch does not compare the source and effective MAC addresses.

To protect against MAC address impersonation, all virtual switches must have forged transmissions set to reject. Reject Forged Transmit can be set at the vSwitch and/or the Portgroup level. Switch-level settings can be overridden at the Portgroup level.

Solution

From the vSphere Client, go to Hosts and Clusters.

Select the ESXi Host >> Configure >> Networking >> Virtual Switches.

On each standard switch, click "Edit" and select Security.

Set "Forged transmits" to "Reject". Click "OK".

For each port group, click the '...' button and select "Edit Settings" then Security.

Set "Forged transmits" to "Reject" and uncheck the "Override" box. Click "OK".

or

From a PowerCLI command prompt while connected to the ESXi host, run the following commands:

Get-VirtualSwitch | Get-SecurityPolicy | Set-SecurityPolicy -ForgedTransmits $false
Get-VirtualPortGroup | Get-SecurityPolicy | Set-SecurityPolicy -ForgedTransmitsInherited $true

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_VMW_vSphere_8-0_Y24M08_STIG.zip

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CAT|II, CCI|CCI-000366, Rule-ID|SV-258771r959010_rule, STIG-ID|ESXI-80-000216, Vuln-ID|V-258771

Plugin: VMware

Control ID: 6b46662113ac2e9d5a1829227ea2d16ca2cd73f80894375d4e6b1f414ce11b13