CISC-RT-000392 - The Cisco perimeter router must be configured to drop IPv6 undetermined transport packets - outside interface

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Information

One of the fragmentation weaknesses known in IPv6 is the undetermined transport packet. This packet contains an undetermined protocol due to fragmentation. Depending on the length of the IPv6 extension header chain, the initial fragment may not contain the layer four port information of the packet.

Solution

Configure the router to drop IPv6 undetermined transport packets 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 ipv6 any any undetermined-transport 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

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS-XR_Router_Y21M04_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(11), CAT|II, CCI|CCI-002403, Rule-ID|SV-230049r533189_rule, STIG-ID|CISC-RT-000392, Vuln-ID|V-230049

Plugin: Cisco

Control ID: a9c67071ee610a6f1aede5ba7088e38ea27f8d89f4b9346901f1571981aa4b39