CISC-RT-000394 - The Cisco perimeter switch must be configured to drop IPv6 packets containing a Hop-by-Hop header with invalid option type values.

Information

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.

Solution

Configure the switch to drop IPv6 packets containing a Hop-by-Hop header with invalid option type values as shown in the example below.

SW1(config)#ipv6 access-list FILTER_IPV6
SW1(config-ipv6-acl)#deny hbh any any dest-option-type 4 log
SW1(config-ipv6-acl)#deny hbh any any dest-option-type 195 log
SW1(config-ipv6-acl)#deny hbh any any dest-option-type home-address 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

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS_Switch_Y24M07_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(11), CAT|II, CCI|CCI-002403, Rule-ID|SV-237765r856667_rule, STIG-ID|CISC-RT-000394, Vuln-ID|V-237765

Plugin: Cisco

Control ID: a89448f21f745c65b329b7c8375944b213429a6c1cc18382c65b022881648213