Windows Server 2019 source routing must be configured to the highest protection level to prevent Internet Protocol (IP) source routing.

STIG ID: WN19-CC-000040  |  SRG: SRG-OS-000480-GPOS-00227 |  Severity: low |  CCI: CCI-000366 |  Vulnerability Id: V-205859 | 

Vulnerability Discussion

Configuring the system to disable IP source routing protects against spoofing.

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: DisableIPSourceRouting

Value Type: REG_DWORD
Value: 0x00000002 (2)

Fix

Configure the policy value for Computer Configuration >> Administrative Templates >> MSS (Legacy) >> "MSS: (DisableIPSourceRouting) IP source routing protection level (protects against packet spoofing)" to "Enabled" with "Highest protection, source routing is completely disabled" selected.

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.
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