IPv6 6-to-4 addresses with a prefix of 2002::/16 must be filtered at the perimeter.

From Firewall Security Technical Implementation Guide - Cisco

Part of IPv6 6-to-4 addresses are not filtered

Associated with IA controls: ECSC-1

SV-20160r2_rule IPv6 6-to-4 addresses with a prefix of 2002::/16 must be filtered at the perimeter.

Vulnerability discussion

"6-to-4" is a tunneling IPv6 transition mechanism [RFC 3056]. The guidance is the default case, which assumes that 6-to-4 is not being used as an IPv6 transition mechanism. If 6-to-4 is implemented, reference addition 6-to-4 guidance defined in the STIG.Drop all inbound IPv6 packets containing a source address of type 2002::/16. This assumes the 6-to-4 transition mechanism is not being used.Drop all inbound IPv6 packets containing a destination address of type 2002::/16. This assumes the 6-to-4 transition mechanism is not being used.

Check content

Review the device configuration to ensure filters are in place to restrict the IP addresses explicitly or implicitly. Verify that ingress and egress ACLs for IPv6 have been defined to deny 6-to-4 tunnel addresses and log all violations. source type: 2002::/16 If filters are not in place to deny 6-to-4 tunnel addresses, this is a finding.

Fix text

Configure the device using filters to restrict IP addresses that contain any 6-to-4 addresses.

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.