The Cisco ASA must be configured to inspect all inbound and outbound IPv6 traffic for unknown or out-of-order extension headers.
An XCCDF Rule
Description
<VulnDiscussion>IPv6 packets with unknown extension headers as well as out-of-order headers can create Denial-of-Service attacks for other networking components as well as host devices. IPv6 inspection can check conformance to RFC 2460 enforcing the order extension headers. While routers only need to examine the IPv6 destination address and the Hop-by-Hop Options header, firewalls must recognize and parse through all existing extension headers since the upper-layer protocol information resides in the last header. An attacker is able to chain many extension headers in order to pass firewall and intrusion detections. An attacker can cause a denial of service if an intermediary device or destination host is not capable of processing an extensive or out-of-order chain of extension headers. Hence, it is imperative the firewall is configured to drop packets with unknown or out-of-order headers.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-239870r665896_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
Configure the firewall to inspect all inbound and outbound IPv6 traffic for unknown or out-of-order extension headers.
Step 1 (optional): Configure an IPv6 inspect policy map.
ASA(config)# policy-map type inspect ipv6 IPV6_MAP
ASA(config-pmap)# parameters