Check: CISC-RT-000395
Cisco IOS XR Router RTR STIG:
CISC-RT-000395
(in versions v2 r4 through v2 r1)
Title
The Cisco perimeter router must be configured to drop IPv6 packets containing a Destination Option header with invalid option type values. (Cat II impact)
Discussion
These options are intended to be for the Hop-by-Hop header only. The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that it cannot recognize. Hence, this could cause a Denial-of-Service on the target device. In addition, the type, length, value (TLV) formatting provides the ability for headers to be very large.
Check Content
This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is compliant with this requirement. Step 1: Verify that an inbound IPv6 ACL has been configured on the external interface. interface interface gigabitethernet 0/2/0/2 ipv6 address 2001::1:0:22/64 ipv6 access-group FILTER_IPV6 ingress Step 2: Verify that the ACL drops IPv6 packets containing a Destination Option header with option type values of 0x05 (Router Alert) or 0xC2 (Jumbo Payload) as shown in the example below. ipv6 access-list FILTER_IPV6 10 deny 60 any any dest-option-type 5 log 20 deny 60 any any dest-option-type 194 log 30 permit ipv6 … … … … 90 deny ipv6 any any log If the router is not configured to drop IPv6 packets containing a Destination Option header with option type values of 0x05 (Router Alert) or 0xC2 (Jumbo Payload), this is a finding.
Fix Text
Configure the router to drop IPv6 packets containing a Destination Option header with option type values of 0x05 (Router Alert) or 0xC2 (Jumbo Payload) as shown in the example below. RP/0/0/CPU0:R3(config)# ipv6 access-list FILTER_IPV6 RP/0/0/CPU0:R3(config-ipv6-acl)# deny 60 any any dest-option-type 5 log RP/0/0/CPU0:R3(config-ipv6-acl)# deny 60 any any dest-option-type 194 log RP/0/0/CPU0:R3(config-ipv6-acl)# permit ipv6 … … … … RP/0/0/CPU0:R3(config-ipv6-acl)# deny ipv6 any any log RP/0/0/CPU0:R3(config-ipv6-acl)# exit RP/0/0/CPU0:R3(config)# interface gigabitethernet 0/2/0/2 RP/0/0/CPU0:R3(config-if)# ipv6 access-group FILTER_IPV6 ingress RP/0/0/CPU0:R3(config-if)# end
Additional Identifiers
Rule ID: SV-230151r856669_rule
Vulnerability ID: V-230151
Group Title: SRG-NET-000364-RTR-000203
Expert Comments
CCIs
Number | Definition |
---|---|
CCI-002403 |
The information system only allows incoming communications from organization-defined authorized sources routed to organization-defined authorized destinations. |
Controls
Number | Title |
---|---|
SC-7 (11) |
Restrict Incoming Communications Traffic |