1.1.1.2.1.84 Set 'MSS: (EnableICMPRedirect) Allow ICMP redirects to override OSPF generated routes' to 'Disabled'

Information

The registry value entry EnableICMPRedirect was added to the template file in the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters\ registry key. The entry appears as MSS: (EnableICMPRedirect) Allow ICMP redirects to override OSPF generated routes in the SCE. Internet Control Message Protocol (ICMP) redirects cause the stack to plumb host routes. These routes override the Open Shortest Path First (OSPF)generated routes. It is recommended to configure this setting to Not Defined for enterprise environments and to Disabled for high security environments. This behavior is expected. The problem is that the 10 minute time-out period for the ICMP redirect-plumbed routes temporarily creates a network situation in which traffic will no longer be routed properly for the affected host.

Solution

To implement the recommended configuration state, set the following Group Policy setting to 0.

Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options\MSS- (EnableICMPRedirect) Allow ICMP redirects to override OSPF generated routes

Impact- When Routing and Remote Access Service (RRAS) is configured as an autonomous system boundary router (ASBR), it does not correctly import connected interface subnet routes. Instead, this router injects host routes into the OSPF routes. However, the OSPF router cannot be used as an ASBR router, and when connected interface subnet routes are imported into OSPF the result is confusing routing tables with strange routing paths.

See Also

https://workbench.cisecurity.org/files/42

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7, CCE|CCE-3725-9, CSCv6|9.2

Plugin: Windows

Control ID: 1d45dda74476b197240a4cfebdb714caa514672ac79d632417f661742bfffd69