CISC-RT-000397 - The Cisco perimeter router must be configured to drop IPv6 packets containing the NSAP address option within Destination Option header.

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Information

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 from RFC 1888 (OSI NSAPs and IPv6) has been deprecated by RFC 4048.

Solution

Configure the router to drop IPv6 packets containing a Destination Option header with option type value of 0xC3 (NSAP address) 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 195 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

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS-XR_Router_Y23M10_STIG.zip

Item Details

References: CAT|II, CCI|CCI-002403, Rule-ID|SV-230157r856673_rule, STIG-ID|CISC-RT-000397, Vuln-ID|V-230157

Plugin: Cisco

Control ID: 8d58b0e5b8bd2ccc18e5e3927abae1d4e2b99cdd9051d4b71393dc81fc4c70eb