Windows Defender Firewall with Advanced Security local firewall rules must not be merged with Group Policy settings when connected to a public network.

A firewall provides a line of defense against attack. To be effective, it must be enabled and properly configured. Local firewall rules will not be merged with Group Policy settings on a public network to prevent Group Policy settings from being changed.

If the system is not a member of a domain, this is NA.

If the firewall's Public Profile is not enabled (see V-17417), this requirement is also a finding.

Verify the registry value below.

If this registry value does not exist or is not configured as specified, this is a finding.

Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SOFTWARE\Policies\Microsoft\WindowsFirewall\PublicProfile\

Value Name: AllowLocalPolicyMerge

Type: REG_DWORD Value: 0x00000000 (0)

If the system is not a member of a domain, this is NA.

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Windows Defender Firewall with Advanced Security >> Windows Defender Firewall with Advanced Security >> Windows Defender Firewall Properties (this link will be in the right pane) >> Public Profile tab >> Settings (select Customize) >> Rule merging, "Apply local firewall rules:" to "No".