Check: CISC-RT-000740
Cisco NX OS Switch RTR STIG:
CISC-RT-000740
(in versions v2 r3 through v1 r0.1)
Title
The Cisco PE switch must be configured with Unicast Reverse Path Forwarding (uRPF) loose mode enabled on all CE-facing interfaces. (Cat II impact)
Discussion
The uRPF feature is a defense against spoofing and denial-of-service (DoS) attacks by verifying if the source address of any ingress packet is reachable. To mitigate attacks that rely on forged source addresses, all provider edge switches must enable uRPF loose mode to guarantee that all packets received from a CE switch contain source addresses that are in the route table.
Check Content
Review the switch configuration to determine if uRPF loose mode is enabled on all CE-facing interfaces. interface Ethernet1/2 ip address x.1.12.2/30 ip access-group BLOCK_TO_CORE in ip verify unicast source reachable-via any If uRPF loose mode is not enabled on all CE-facing interfaces, this is a finding.
Fix Text
Configure uRPF loose mode on all CE-facing interfaces as shown in the example below: SW1(config)# int e1/2 SW1(config-if)# ip verify unicast source reachable-via any SW1(config-if)# end
Additional Identifiers
Rule ID: SV-221127r622190_rule
Vulnerability ID: V-221127
Group Title: SRG-NET-000205-RTR-000008
Expert Comments
CCIs
Number | Definition |
---|---|
CCI-001097 |
The information system monitors and controls communications at the external boundary of the information system and at key internal boundaries within the system. |
Controls
Number | Title |
---|---|
SC-7 |
Boundary Protection |