Vulnerability Note VU#101321

Microsoft Windows Vista Teredo IPv6 interface firewall bypass vulnerability

Overview

A vulnerability in the Microsoft Windows Vista firewall may allow an attacker to send unfiltered IPv6 traffic to a vulnerable system.

I. Description

Internet Protocol version 6 (IPv6) is an IP standard that is designed to replace the Internet Protocol version 4 (IPv4). The Microsoft Teredo service is used by Microsoft Windows Vista, XP, and Server 2003 to allow clients with only IPv4 connectivity to obtain and use publicly routable IPv6 addresses.

The Teredo service must be manually enabled by an administrator in Windows XP and Server 2003. The Teredo service is enabled by default in Windows Vista, but is not activated until an application requests an IPv6 address.

The Windows firewall does not properly apply stateful packet inspection rules to incoming Teredo traffic.

Note that the Teredo service may create a tunnel through perimeter firewalls, bypassing access control lists and content inspection filtering. See RFC 4380 section 7.1 for more details.

II. Impact

A remote, unautheticated attacker may be able to send unsolicited and unfiltered IPv6 traffic to a vulnerable system.

III. Solution

Update

Microsoft has released an update to address this issue. Users are encourgaed to review Microsoft Security Bulletin MS07-038 and take appropriate action.

Disable Teredo

Disabling the Teredo service will mitigate this vulnerability. See Microsoft Security Bulletin MS07-038 for information on how to disable Teredo.

Systems Affected

Vendor	Status	Date Updated
Microsoft Corporation	Vulnerable	10-Jul-2007

References

http://www.microsoft.com/technet/security/bulletin/ms07-038.mspx
http://tools.ietf.org/html/rfc4380#section-7.1
http://en.wikipedia.org/wiki/IPv6
http://www.microsoft.com/technet/network/ipv6/teredo.mspx
http://www.symantec.com/avcenter/reference/Teredo_Security.pdf

Credit

Thanks to Symantec and Microsoft for information that was used in this report.

This document was written by Ryan Giobbi.

Other Information

Date Public	07/10/2007
Date First Published	07/10/2007 08:44:33 PM
Date Last Updated	07/11/2007
CERT Advisory
CVE Name	CVE-2007-3038
Metric	1.35
Document Revision	13

If you have feedback, comments, or additional information about this vulnerability, please send us email.