Windows Server 2019 must be configured to prevent Internet Control Message Protocol (ICMP) redirects from overriding Open Shortest Path First (OSPF)-generated routes.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
low	V-205860	SRG-OS-000480-GPOS-00227	WN19-CC-000050	SV-205860r991589_rule	2025-02-25	3

Description
Allowing ICMP redirect of routes can lead to traffic not being routed properly. When disabled, this forces ICMP to be routed via the shortest path first.

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\Tcpip\Parameters\ Value Name: EnableICMPRedirect Value Type: REG_DWORD Value: 0x00000000 (0)

✔️ Fix
Configure the policy value for Computer Configuration >> Administrative Templates >> MSS (Legacy) >> "MSS: (EnableICMPRedirect) Allow ICMP redirects to override OSPF generated routes" to "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: (EnableICMPRedirect) Allow ICMP redirects to override OSPF generated routes" to "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.