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             AUSCERT External Security Bulletin Redistribution

      Vulnerability in Windows ISATAP Component Could Allow Spoofing
                               14 April 2010


        AusCERT Security Bulletin Summary

Product:           Windows ISATAP
Publisher:         Microsoft
Operating System:  Windows Server 2008
                   Windows Server 2003
                   Windows Vista
                   Windows XP
Impact/Access:     Provide Misleading Information -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2010-0812  

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------

Microsoft Security Bulletin (978338)

Vulnerability in Windows ISATAP Component Could Allow Spoofing

Published: April 13, 2010

Version: 1.0

General Information

Executive Summary

  This security update resolves one privately reported vulnerability in
  Microsoft Windows. This security update is rated Moderate for Windows XP,
  Windows Server 2003, Windows Vista, and Windows Server 2008. Windows 7 and
  Windows Server 2008 R2 are not vulnerable because these operating systems
  include the feature deployed by this security update.

  This vulnerability could allow an attacker to spoof an IPv4 address so that it
  may bypass filtering devices that rely on the source IPv4 address. The
  security update addresses the vulnerability by changing the manner in which
  the Windows TCP/IP stack checks the source IPv6 address in a tunneled ISATAP

  Recommendation: The majority of customers have automatic updating enabled and
  will not need to take any action because this security update will be
  downloaded and installed automatically. Customers who have not enabled
  automatic updating need to check for updates and install this update manually.
  For information about specific configuration options in automatic updating,
  see Microsoft Knowledge Base Article 294871.

  For administrators and enterprise installations, or end users who want to
  install this security update manually, Microsoft recommends that customers
  consider applying the security update using update management software, or by
  checking for updates using the Microsoft Update service.

Affected Software

  Windows XP Service Pack 2
  Windows XP Service Pack 3
  Windows XP Professional x64 Edition Service Pack 2
  Windows Server 2003 Service Pack 2
  Windows Server 2003 x64 Edition Service Pack 2
  Windows Server 2003 with SP2 for Itanium-based Systems
  Windows Vista
  Windows Vista Service Pack 1
  Windows Vista Service Pack 2
  Windows Vista x64 Edition
  Windows Vista x64 Edition Service Pack 1
  Windows Vista x64 Edition Service Pack 2
  Windows Server 2008 for 32-bit Systems
  Windows Server 2008 for 32-bit Systems Service Pack 2
  Windows Server 2008 for x64-based Systems
  Windows Server 2008 for x64-based Systems Service Pack 2
  Windows Server 2008 for Itanium-based Systems
  Windows Server 2008 for Itanium-based Systems Service Pack 2

Mitigating Factors

  This vulnerability only impacts Windows systems with the ISATAP interface


Block IP Protocol Type 41 (ISATAP) at the firewall

  The ISATAP protocol is defined as protocol type 41 by RFC4214: Intra-Site
  Automatic Tunnel Addressing Protocol (ISATAP). Blocking this protocol type at
  the firewall will help protect systems that are behind that firewall from
  attempts to exploit this vulnerability. Microsoft recommends that you block
  all unsolicited inbound communication from the Internet to help prevent
  attacks that may use other ports or protocols.

Disable the ISATAP IPv6 interface

  To disable the ISATAP IPv6 interface, run the following command from an
  elevated command prompt:

    netsh interface isatap set state disabled

  Note: You must be logged in as administrator or have administrative
  credentials to complete this workaround.

Vulnerability Information

ISATAP IPv6 Source Address Spoofing Vulnerability - CVE-2010-0812

  A spoofing vulnerability exists in the Microsoft Windows IPv6 stack due to the
  way that Windows checks the inner packet's IPv6 source address in a tunneled
  ISATAP packet. An attacker who successfully exploited this vulnerability could
  impersonate an address to bypass edge or host firewalls. Additionally,
  information could be disclosed when the targeted computer replies to the
  message using the source IPv6 address that the attacker specified.

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