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-242004	WNFWA-000024	SV-242004r698253_rule		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
Microsoft Windows Firewall with Advanced Security Security Technical Implementation Guide	2021-10-15

Details

Check Text ( C-45279r698251_chk )
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)

Check Text ( C-45279r698251_chk )

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)

Fix Text (F-45238r698252_fix)
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 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".

Fix Text (F-45238r698252_fix)

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 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".