The Cisco PE router must be configured to ignore or block all packets with any IP options.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-217009	CISC-RT-000750	SV-217009r531087_rule		Medium

Description
Packets with IP options are not fast switched and therefore must be punted to the router processor. Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of packets with IP options. Dropping the packets with IP options reduces the load of IP options packets on the router. The end result is a reduction in the effects of the DoS attack on the router and on downstream routers.

Description

Packets with IP options are not fast switched and therefore must be punted to the router processor. Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of packets with IP options. Dropping the packets with IP options reduces the load of IP options packets on the router. The end result is a reduction in the effects of the DoS attack on the router and on downstream routers.

STIG	Date
Cisco IOS XR Router RTR Security Technical Implementation Guide	2020-09-23

Details

Check Text ( C-18239r288867_chk )
In Cisco IOS XR, all IPv4 packets with any header option other than the "source-route" header options are dropped. By default, ipv4 source routing is disabled. Verify that the following command is not configured: ipv4 source-route If the router is not configured to drop all packets with IP options, this is a finding.

Fix Text (F-18237r288868_fix)
Configure the router to drop all packets with ipv4 source-route as shown below. RP/0/0/CPU0:R3(config)#no ipv4 source-route