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  Microsoft Windows ISATAP IPv6 address spoofing

From:MICROSOFT <secure_(at)_microsoft.com>
Date:16.04.2010
Subject:Microsoft Security Bulletin MS10-029 - Moderate Vulnerability in Windows ISATAP Component Could Allow Spoofing (978338)

Microsoft Security Bulletin MS10-029 - Moderate
Vulnerability in Windows ISATAP Component Could Allow Spoofing (978338)
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. For more information, see the subsection, Affected and Non-Affected Software, in this section.

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 packet. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

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.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

Known Issues. None
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Affected and Non-Affected Software

The following software have been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, visit Microsoft Support Lifecycle.

Affected Software
Operating System Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by this Update

Windows XP Service Pack 2 and Windows XP Service Pack 3


Spoofing


Moderate


None

Windows XP Professional x64 Edition Service Pack 2


Spoofing


Moderate


None

Windows Server 2003 Service Pack 2


Spoofing


Moderate


None

Windows Server 2003 x64 Edition Service Pack 2


Spoofing


Moderate


None

Windows Server 2003 with SP2 for Itanium-based Systems


Spoofing


Moderate


None

Windows Vista, Windows Vista Service Pack 1, and Windows Vista Service Pack 2


Spoofing


Moderate


None

Windows Vista x64 Edition, Windows Vista x64 Edition Service Pack 1, and Windows Vista x64 Edition Service Pack 2


Spoofing


Moderate


None

Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2*


Spoofing


Moderate


None

Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2*


Spoofing


Moderate


None

Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2


Spoofing


Moderate


None

*Server Core installation affected. This update applies, with the same severity rating, to supported editions of Windows Server 2008 as indicated, whether or not installed using the Server Core installation option. For more information on this installation option, see the MSDN article, Server Core. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008; see Compare Server Core Installation Options.

Non-Affected Software
Operating System

Microsoft Windows 2000 Service Pack 4

Windows 7 for 32-bit Systems

Windows 7 for x64-based Systems

Windows Server 2008 R2 for x64-based Systems

Windows Server 2008 R2 for Itanium-based Systems
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Frequently Asked Questions (FAQ) Related to This Security Update

Does this update contain any security-related changes to functionality?
This security update implements two new security features:


Potential Router List (PRL) on ISATAP clients: PRL enables clients to do source address checking for incoming ISATAP tunneled packets. PRL is enabled by default upon installing this security update and helps address the ISATAP IPv6 Source Address Spoofing Vulnerability described in CVE-2010-0812. More information on PRL can be found in Microsoft Knowledge Base Article 978338.


Neighbor Unreachability Detection (NUD) on ISATAP interfaces: NUD is used to validate whether a neighbor is reachable or not. NUD is performed by the ISATAP nodes before sending ISATAP packets. NUD is not enabled by default and needs to be manually configured by network administrators. More information on NUD and how to enable it can be found in Microsoft Knowledge Base Article 978338.

Why is Microsoft Windows 2000 not affected by this vulnerability?
Microsoft Windows 2000 does not include support for IPv6 and therefore, this operating system is not vulnerable.

Why are Windows 7 and Windows Server 2008 R2 not affected by this vulnerability?
The features deployed by this security update, Potential Router List (PRL) and Neighbor Unreachability Detection (NUD), are already present in Windows 7 and Windows Server 2008 R2.

Note While PRL is enabled by default on these platforms, NUD is not, and must be manually configured by the network administrator. Please review Microsoft Knowledge Base Article 978338 for additional information on this feature.

Will this update be offered even if I do not have IPv6 enabled?
Yes, this security update will be offered through Automatic Updates because the vulnerable code exists on these systems. We recommend that customers install the security update if they plan to deploy IPv6 in the future.

Where are the file information details?
Refer to the reference tables in the Security Update Deployment section for the location of the file information details.

I am using an older release of the software discussed in this security bulletin. What should I do?
The affected software listed in this bulletin have been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, visit the Microsoft Support Lifecycle Web site.

It should be a priority for customers who have older releases of the software to migrate to supported releases to prevent potential exposure to vulnerabilities. To determine the support lifecycle for your software release, see Select a Product for Lifecycle Information. For more information about service packs for these software releases, see Lifecycle Supported Service Packs.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, visit the Microsoft Worldwide Information Web site, select the country in the Contact Information list, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Microsoft Support Lifecycle Policy FAQ.
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Vulnerability Information

Severity Ratings and Vulnerability Identifiers

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the April bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software ISATAP IPv6 Source Address Spoofing Vulnerability - CVE-2010-0812 Aggregate Severity Rating

Windows XP Service Pack 2 and Windows XP Service Pack 3


Moderate
Spoofing


Moderate

Windows XP Professional x64 Edition Service Pack 2


Moderate
Spoofing


Moderate

Windows Server 2003 Service Pack 2


Moderate
Spoofing


Moderate

Windows Server 2003 x64 Edition Service Pack 2


Moderate
Spoofing


Moderate

Windows Server 2003 with SP2 for Itanium-based Systems


Moderate
Spoofing


Moderate

Windows Vista, Windows Vista Service Pack 1, and Windows Vista Service Pack 2


Moderate
Spoofing


Moderate

Windows Vista x64 Edition, Windows Vista x64 Edition Service Pack 1, and Windows Vista x64 Edition Service Pack 2


Moderate
Spoofing


Moderate

Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2*


Moderate
Spoofing


Moderate

Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2*


Moderate
Spoofing


Moderate

Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2


Moderate
Spoofing


Moderate

*Server Core installation affected. This update applies, with the same severity rating, to supported editions of Windows Server 2008, whether or not installed using the Server Core installation option. For more information on this installation option, see the MSDN article, Server Core. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008; see Compare Server Core Installation Options.
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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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0812.

Mitigating Factors for ISATAP IPv6 Source Address Spoofing Vulnerability - CVE-2010-0812

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:


This vulnerability only impacts Windows systems with the ISATAP interface configured.
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Workarounds for ISATAP IPv6 Source Address Spoofing Vulnerability - CVE-2010-0812

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:


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.

Impact of workaround. Disabling the ISATAP interface will prevent the system from using ISATAP as an IPv6 tunneling mechanism.

How to undo the workaround.

To re-enable the ISATAP IPv6 interface, run the following command from an elevated command prompt:

netsh interface isatap set state enabled

Note You must be logged in as administrator or have administrative credentials to undo this workaround.
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FAQ for ISATAP IPv6 Source Address Spoofing Vulnerability - CVE-2010-0812

What is the scope of the vulnerability?
This is a spoofing vulnerability. This vulnerability could enable an attacker to spoof an IPv4 address to bypass filtering devices that rely on the source IPv4 address.

What causes the vulnerability?
The vulnerability exists because the Windows TCP/IP stack does not properly check the source IPv6 address in a tunneled ISATAP packet.

What is ISATAP?
The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) provides IPv6 connectivity within an IPv4 Intranet. For information on ISATAP, see RFC5214: Intra-Site Automatic Tunnel Addressing Protocol (ISATAP).

What might an attacker use the vulnerability to do?
An attacker may be able to impersonate another user or system which could allow source address filters, such as edge or host firewalls, to be bypassed.

How could an attacker exploit the vulnerability?
An attacker could try to exploit the vulnerability by creating specially crafted network packets with a specially crafted IPv6 source address in an ISATAP connection that does not match the corresponding IPv4 source address.

What systems are primarily at risk from the vulnerability?
All operating systems with the IPv6 ISATAP features enabled are at risk from this vulnerability.

What does the update do?
The update addresses this vulnerability by changing the manner in which the Windows TCP/IP stack checks the source IPv6 address in a tunneled ISATAP packet.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.


Other Information
Acknowledgments

Microsoft thanks the following for working with us to help protect customers:

Gabi Nakibly of the National EW Research & Simulation Center (at Rafael) for reporting the ISATAP IPv6 Source Address Spoofing Vulnerability (CVE-2010-0812)
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Microsoft Active Protections Program (MAPP)

To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please visit the active protections Web sites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Support


Customers in the U.S. and Canada can receive technical support from Security Support or 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates. For more information about available support options, see Microsoft Help and Support.


International customers can receive support from their local Microsoft subsidiaries. There is no charge for support that is associated with security updates. For more information about how to contact Microsoft for support issues, visit the International Support Web site.

Disclaimer

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

Revisions


V1.0 (April 13, 2010): Bulletin published.

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