Check: CISC-RT-000396
Cisco IOS XE Switch RTR STIG:
CISC-RT-000396
(in versions v2 r5 through v2 r1)
Title
The Cisco perimeter switch must be configured to drop IPv6 packets containing an extension header with the Endpoint Identification option. (Cat II impact)
Discussion
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. This option type is associated with the Nimrod Routing system and has no defining RFC document.
Check Content
This requirement is not applicable for the DODIN Backbone. Review the switch 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 an extension header with the Endpoint Identification option as shown in the example below. ipv6 access-list FILTER_IPV6 deny any any dest-option-type 138 log permit ipv6 … … … … deny ipv6 any any log If the switch is not configured to drop IPv6 packets containing an extension header with the Endpoint Identification option, this is a finding.
Fix Text
Configure the switch to drop IPv6 packets containing an option type values of 0x8A (Endpoint Identification) regardless of whether it appears in a Hop-by-Hop or Destination Option header as shown in the example below. SW1(config)#ipv6 access-list FILTER_IPV6 SW1(config-ipv6-acl)#deny any any dest-option-type 138 log SW1(config-ipv6-acl)#permit ipv6 … … … … SW1(config-ipv6-acl)# deny ipv6 any any log SW1(config-ipv6-acl)#exit SW1(config)#int g1/0 SW1(config-if)#ipv6 traffic-filter FILTER_IPV6 SW1(config-if)#end
Additional Identifiers
Rule ID: SV-237774r856671_rule
Vulnerability ID: V-237774
Group Title: SRG-NET-000364-RTR-000204
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 |