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.
An XCCDF Rule
Description
<VulnDiscussion>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. </VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-237778r856675_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
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