Information
IP source routing is a mechanism that allows the sender to determine the IP route that a datagram should follow through the network.
The recommended state for this setting is: Enabled: Highest protection, source routing is completely disabled.
Rationale:
An attacker could use source routed packets to obscure their identity and location. Source routing allows a computer that sends a packet to specify the route that the packet takes.
Impact:
All incoming source routed packets will be dropped.
Solution
To establish the recommended configuration via GP, set the following UI path to Enabled: Highest protection, source routing is completely disabled:
Computer Configuration\Policies\Administrative Templates\MSS (Legacy)\MSS: (DisableIPSourceRouting IPv6) IP source routing protection level (protects against packet spoofing)
Note: This Group Policy path does not exist by default. An additional Group Policy template (MSS-legacy.admx/adml) is required - it is available from this TechNet blog post: The MSS settings - Microsoft Security Guidance blog
Default Value:
No additional protection, source routed packets are allowed.