STIGQter: STIG Summary: Cisco IOS Switch RTR Security Technical Implementation Guide Version: 2 Release: 1 Benchmark Date: 23 Apr 2021:

The Cisco perimeter switch must be configured to drop IPv6 packets containing a Hop-by-Hop or Destination Option extension header with an undefined option type.

DISA Rule

SV-237777r648822_rule

Vulnerability Number

V-237777

Group Title

SRG-NET-000364-RTR-000206

Rule Version

CISC-RT-000398

Severity

CAT II

CCI(s)

• CCI-002403 - The information system only allows incoming communications from organization-defined authorized sources routed to organization-defined authorized destinations.

Weight

10

Fix Recommendation

Configure the switch to drop all inbound IPv6 packets containing an undefined option type value regardless of whether they appear 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 2
SW1(config-ipv6-acl)#deny any any dest-option-type 3
SW1(config-ipv6-acl)#deny any any dest-option-type 6
SW1(config-ipv6-acl)#deny any any dest-option-type 9
SW1(config-ipv6-acl)#deny any any dest-option-type 10
SW1(config-ipv6-acl)#deny any any dest-option-type 11
SW1(config-ipv6-acl)#deny any any dest-option-type 12
SW1(config-ipv6-acl)#deny any any dest-option-type 13
SW1(config-ipv6-acl)#deny any any dest-option-type 14
SW1(config-ipv6-acl)#deny any any dest-option-type 16
…
SW1(config-ipv6-acl)#deny any any dest-option-type 34
SW1(config-ipv6-acl)#deny any any dest-option-type 36
SW1(config-ipv6-acl)#deny any any dest-option-type 37
SW1(config-ipv6-acl)#deny any any dest-option-type 39
…
SW1(config-ipv6-acl)#deny any any dest-option-type 47
SW1(config-ipv6-acl)#deny any any dest-option-type 49
…
SW1(config-ipv6-acl)#deny any any dest-option-type 255
SW1(config-ipv6-acl)#permit …
…
…
…
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

Check Contents

This requirement is not applicable for the DODIN Backbone.

Review the switch configuration and determine if filters are bound to the applicable interfaces to drop all inbound IPv6 packets containing an undefined option type value regardless of whether they appear in a Hop-by-Hop or Destination Option header. Undefined values are 0x02, 0x03, 0x06, 0x9 – 0xE, 0x10 – 0x22, 0x24, 0x25, 0x27 – 0x2F, and 0x31 – 0xFF.

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 or Destination Option extension header with an undefined option type as shown in the example below.

ipv6 access-list FILTER_IPV6
deny any any dest-option-type 2
deny any any dest-option-type 3
deny any any dest-option-type 6
deny any any dest-option-type 9
deny any any dest-option-type 10
deny any any dest-option-type 11
deny any any dest-option-type 12
deny any any dest-option-type 13
deny any any dest-option-type 14
deny any any dest-option-type 16
…
deny any any dest-option-type 34
deny any any dest-option-type 36
deny any any dest-option-type 37
deny any any dest-option-type 39
…
deny any any dest-option-type 47
deny any any dest-option-type 49
…
deny any any dest-option-type 255
permit …
…
…
…
deny ipv6 any any log

Note: Because hop-by-hop and destination options have the same exact header format, they can be combined under the dest-option-type keyword. Since Hop-by-Hop and Destination Option headers have non-overlapping types, you can use dest-option-type to match either.

If the switch is not configured to drop IPv6 packets containing a Hop-by-Hop or Destination Option extension header with an undefined option type, this is a finding.

Vulnerability Number

V-237777

Documentable

False

Rule Version

CISC-RT-000398

Severity Override Guidance

This requirement is not applicable for the DODIN Backbone.

Review the switch configuration and determine if filters are bound to the applicable interfaces to drop all inbound IPv6 packets containing an undefined option type value regardless of whether they appear in a Hop-by-Hop or Destination Option header. Undefined values are 0x02, 0x03, 0x06, 0x9 – 0xE, 0x10 – 0x22, 0x24, 0x25, 0x27 – 0x2F, and 0x31 – 0xFF.

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 or Destination Option extension header with an undefined option type as shown in the example below.

ipv6 access-list FILTER_IPV6
deny any any dest-option-type 2
deny any any dest-option-type 3
deny any any dest-option-type 6
deny any any dest-option-type 9
deny any any dest-option-type 10
deny any any dest-option-type 11
deny any any dest-option-type 12
deny any any dest-option-type 13
deny any any dest-option-type 14
deny any any dest-option-type 16
…
deny any any dest-option-type 34
deny any any dest-option-type 36
deny any any dest-option-type 37
deny any any dest-option-type 39
…
deny any any dest-option-type 47
deny any any dest-option-type 49
…
deny any any dest-option-type 255
permit …
…
…
…
deny ipv6 any any log

Note: Because hop-by-hop and destination options have the same exact header format, they can be combined under the dest-option-type keyword. Since Hop-by-Hop and Destination Option headers have non-overlapping types, you can use dest-option-type to match either.

If the switch is not configured to drop IPv6 packets containing a Hop-by-Hop or Destination Option extension header with an undefined option type, this is a finding.

Check Content Reference

M

Target Key

4065

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