Check: CISC-RT-000394
Cisco IOS XE Router RTR STIG:
CISC-RT-000394
(in versions v2 r9 through v2 r1)
Title
The Cisco perimeter router must be configured to drop IPv6 packets containing a Hop-by-Hop header with invalid option type values. (Cat II impact)
Discussion
These options are intended to be for the Destination Options 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 and hence 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 gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 traffic-filter FILTER_IPV6 in Step 2: Verify that the ACL drops IPv6 packets containing a Hop-by-Hop header with option type values of 0x04 (Tunnel Encapsulation Limit), 0xC9 (Home Address Destination), or 0xC3 (NSAP Address) as shown in the example below. ipv6 access-list FILTER_IPV6 deny hbh any any dest-option-type 4 log deny hbh any any dest-option-type 195 log deny hbh any any dest-option-type home-address log permit ipv6 … … … … deny ipv6 any any log If the router is not configured to drop IPv6 packets containing a Hop-by-Hop header with invalid option type values, this is a finding.
Fix Text
Drop IPv6 packets containing a Hop-by-Hop header as shown in the example below. R1(config)#ipv6 access-list FILTER_IPV6 R1(config-ipv6-acl)#deny hbh any any dest-option-type 4 log R1(config-ipv6-acl)#deny hbh any any dest-option-type 195 log R1(config-ipv6-acl)#deny hbh any any dest-option-type home-address log R1(config-ipv6-acl)# permit ipv6 … … … … R1(config-ipv6-acl)#deny ipv6 any any log R1(config-ipv6-acl)#exit R1(config)#int g1/0 R1(config-if)#ipv6 traffic-filter FILTER_IPV6 R1(config-if)#end
Additional Identifiers
Rule ID: SV-230146r855847_rule
Vulnerability ID: V-230146
Group Title: SRG-NET-000364-RTR-000202
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 |