Details

Teredo (RFC 4380) is a tunneling mechanism that allows computers to encapsulate IPv6 packets inside IPv4 to traverse IPv4-only networks. It relies on UDP to allow the tunnel to traverse NAT devices. Teredo uses UDP port 3544 to communicate with Teredo relays which access the packet, decapsulated the packet, and route it to the appropriate IPv6 network. While Teredo was proposed by Microsoft, Linux versions do exist.

By allowing Teredo tunneling mechanism to be uncontrolled, it can pass malicious IPv6 packets over IPv4 without further inspection of the packet by router and firewall ACLs.

Solution

Configure either the perimeter router or firewall to block UDP port 3544 traffic inbound and outbound.

Supportive Information

The following resource is also helpful.

• https://iasecontent.disa.mil/stigs/zip/U_Network_Firewall_V8R25_STIG.zip

This security hardening control applies to the following category of controls within NIST 800-53: System and Communications Protection.This control applies to the following type of system Cisco.

References

• 800-53|SC-7(5)
• CAT|I
• Rule-ID|SV-16075r5_rule
• STIG-ID|NET-TUNL-020
• Vuln-ID|V-15294

Source

• Tenable.com/audits