IPv6 source routing must be configured to highest protection.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-220795	SRG-OS-000480-GPOS-00227	WN10-CC-000020	SV-220795r991589_rule	2025-02-25	3

Description
Configuring the system to disable IPv6 source routing protects against spoofing.

ℹ️ Check
If the following registry value does not exist or is not configured as specified, this is a finding: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\ Value Name: DisableIpSourceRouting Value Type: REG_DWORD Value: 2

✔️ Fix
Configure the policy value for Computer Configuration >> Administrative Templates >> MSS (Legacy) >> "MSS: (DisableIPSourceRouting IPv6) IP source routing protection level (protects against packet spoofing)" to "Highest protection, source routing is completely disabled". This policy setting requires the installation of the MSS-Legacy custom templates included with the STIG package. "MSS-Legacy.admx" and " MSS-Legacy.adml" must be copied to the \Windows\PolicyDefinitions and \Windows\PolicyDefinitions\en-US directories respectively.

✔️ Fix

Configure the policy value for Computer Configuration >> Administrative Templates >> MSS (Legacy) >> "MSS: (DisableIPSourceRouting IPv6) IP source routing protection level (protects against packet spoofing)" to "Highest protection, source routing is completely disabled". This policy setting requires the installation of the MSS-Legacy custom templates included with the STIG package. "MSS-Legacy.admx" and " MSS-Legacy.adml" must be copied to the \Windows\PolicyDefinitions and \Windows\PolicyDefinitions\en-US directories respectively.