The vCenter Server must set the distributed port group Promiscuous Mode policy to "Reject".

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-256350	SRG-APP-000516	VCSA-70-000270	SV-256350r942490_rule	2023-12-21	1

Description
When promiscuous mode is enabled for a virtual switch, all virtual machines connected to the port group have the potential of reading all packets across that network, meaning only the virtual machines connected to that port group. Promiscuous mode is disabled by default on the ESXi Server, and this is the recommended setting.

ℹ️ Check
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 "Promiscuous Mode" 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 "Promiscuous Mode" policy is set to "Accept", and is not documented as an exception, this is a finding.

ℹ️ Check

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 "Promiscuous Mode" 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 "Promiscuous Mode" policy is set to "Accept", and is not documented as an exception, this is a finding.

✔️ 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 "Promiscuous Mode" 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 -AllowPromiscuous $false Get-VDPortgroup \| ?{$_.IsUplink -eq $false} \| Get-VDSecurityPolicy \| Set-VDSecurityPolicy -AllowPromiscuous $false

✔️ 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 "Promiscuous Mode" 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 -AllowPromiscuous $false Get-VDPortgroup | ?{$_.IsUplink -eq $false} | Get-VDSecurityPolicy | Set-VDSecurityPolicy -AllowPromiscuous $false