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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17442	WNFWA-000024	SV-54917r1_rule	ECSC-1	Medium

Description
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.

STIG	Date
Windows Firewall with Advanced Security Security Technical Implementation Guide	2014-01-07

Details

Check Text ( C-48671r2_chk )
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: 0

Fix Text (F-47785r1_fix)
Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Windows Firewall with Advanced Security -> Windows Firewall with Advanced Security -> Windows Firewall Properties (this link will be in the right pane) -> Public Profile Tab -> Settings (select Customize) -> Rule merging, "Apply local firewall rules:" to "No".