Windows Defender Firewall with Advanced Security local connection 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-242005	WNFWA-000025	SV-242005r922960_rule		Medium

Description
A firewall provides a line of defense against attack. To be effective, it must be enabled and properly configured. Local connection 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 Defender Firewall with Advanced Security Security Technical Implementation Guide	2023-08-23

Details

Check Text ( C-45280r698254_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: AllowLocalIPsecPolicyMerge Type: REG_DWORD Value: 0x00000000 (0)

Check Text ( C-45280r698254_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: AllowLocalIPsecPolicyMerge

Type: REG_DWORD
Value: 0x00000000 (0)

Fix Text (F-45239r922959_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 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 connection security rules:" to "No".

Fix Text (F-45239r922959_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 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 connection security rules:" to "No".