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  Microsoft Windows / Internet Explorer 0-day vulnerability

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  [Full-disclosure] [SECURITY] Sunbelt Software: New Microsoft Internet Explorer Expolit - 9-18-2006

From:MICROSOFT <secure_(at)_microsoft.com>
Date:27.09.2006
Subject:Microsoft Security Bulletin MS06-055 Vulnerability in Vector Markup Language Could Allow Remote Code Execution (925486)

Microsoft Security Bulletin MS06-055
Vulnerability in Vector Markup Language Could Allow Remote Code Execution (925486)
Published: September 26, 2006

Version: 1.0
Summary

Who Should Read this Document: Customers who use Microsoft Windows

Impact of Vulnerability: Remote Code Execution

Maximum Severity Rating: Critical

Recommendation: Customers should apply the update immediately

Security Update Replacement: This bulletin replaces a prior security update. See the frequently asked questions (FAQ) section of this bulletin for the complete list.

Caveats: None

Tested Software and Security Update Download Locations:

Affected Software:


Microsoft Windows XP Service Pack 1 — Download the update


Microsoft Windows XP Service Pack 2 — Download the update


Microsoft Windows XP Professional x64 Edition — Download the update


Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1 — Download the update


Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based Systems — Download the update


Microsoft Windows Server 2003 x64 Edition — Download the update

Tested Microsoft Windows Components:

Affected Components:


Internet Explorer 5.01 Service Pack 4 on Microsoft Windows 2000 Service Pack 4 — Download the update


Internet Explorer 6 Service Pack 1 on Microsoft Windows 2000 Service Pack 4 — Download the update

The software in this list has been tested to determine whether the versions are affected. Other versions either no longer include security update support or may not be affected. To determine the support life cycle for your product and version, visit the Microsoft Support Lifecycle Web site.

Note The security updates for Microsoft Windows Server 2003, Windows Server 2003 Service Pack 1, and Windows Server 2003 x64 Edition also apply to Windows Server 2003 R2.
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General Information

Executive Summary

Executive Summary:

This update resolves a public vulnerability as well as additional issues discovered through internal investigations. The vulnerability is documented in the "Vulnerability Details" section of this bulletin.

If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

We recommend that customers apply the update immediately.

Severity Ratings and Vulnerability Identifiers:
Vulnerability Identifiers Impact of Vulnerability Windows 2000 Service Pack 4 Windows XP Service Pack 1 Windows XP Service Pack 2 Windows Server 2003 Windows Server 2003 Service Pack 1

VML Buffer Overrun Vulnerability - CVE-2006-4868


Remote Code Execution


Critical


Critical


Critical


Critical


Moderate

This assessment is based on the types of systems that are affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them.

Note By default, Internet Explorer on Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. See the FAQ section for this security update for more information about Internet Explorer Enhanced Security Configuration.

Note The severity ratings for non-x86 operating system versions map to the x86 operating systems versions as follows:


The Windows XP Professional x64 Edition severity rating is the same as the Windows Server XP Service Pack 2.


The Windows Server 2003 for Itanium-based Systems severity rating is the same as the Windows Server 2003 severity rating.


The Windows Server 2003 with SP1 for Itanium-based Systems severity rating is the same as the Windows Server 2003 Service Pack 1 severity rating.


The Windows Server 2003 x64 Edition severity rating is the same as the Windows Server 2003 Service Pack 1 severity rating.
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Frequently Asked Questions (FAQ) Related to This Security Update

Can I deploy this security update after I have applied the workarounds provided in Microsoft Security Advisory 925568?
If the workaround “Modify the Access Control List on Vgx.dll to be more restrictive” has been applied to systems, the security updates provided with this security bulletin may not install correctly. See the Workarounds for VML Buffer Overrun Vulnerability – CVE-2006-4868 section in this security bulletin for instructions on how to revert this workaround before applying this security update.

What updates does this release replace?
This security update replaces a prior security update. The security bulletin ID and affected operating systems are listed in the following table.
Bulletin ID Windows 2000 Service Pack 4 Windows 2000 Service Pack 4 with Internet Explorer 6 Service Pack 1 Installed Windows XP Service Pack 1 Windows XP Service Pack 2 Windows Server 2003 Windows Server 2003 Service Pack 1

MS04-028


Not Replaced


Replaced


Not Replaced


Not Replaced


Not Replaced


Not Replaced

Why are the security updates for Windows XP Service Pack 1 and Windows 2000 Service Pack 4 labeled as Internet Explorer Updates?
While this is a security update for Windows, the files are serviced from the Internet Explorer code base on these platforms. As such, it follows Internet Explorer standards for packaging as well as detection and deployment.

What is the Internet Explorer Enhanced Security Configuration?
Internet Explorer Enhanced Security Configuration is a group of preconfigured Internet Explorer settings that reduce the likelihood of a user or of an administrator downloading and running specially crafted Web content on a server. Internet Explorer Enhanced Security Configuration reduces this risk by modifying many security-related settings. This includes the settings on the Security tab and the Advanced tab in the Internet Options dialog box. Some of the important modifications include the following:


Security level for the Internet zone is set to High. This setting disables scripts, ActiveX controls, Microsoft Java Virtual Machine (MSJVM), and file downloads.


Automatic detection of intranet sites is disabled. This setting assigns all intranet Web sites and all Universal Naming Convention (UNC) paths that are not explicitly listed in the Local intranet zone to the Internet zone.


Install On Demand and non-Microsoft browser extensions are disabled. This setting prevents Web pages from automatically installing components and prevents non-Microsoft extensions from running.


Multimedia content is disabled. This setting prevents music, animations, and video clips from running.

The Internet Explorer Enhanced Security Configuration does not provide mitigation for applications like Microsoft Outlook which can be installed on Windows Server 2003.

Extended security update support for Microsoft Windows 98, Windows 98 Second Edition, or Windows Millennium Edition ended on July 11, 2006. I am still using one of these operating systems; what should I do?
Windows 98, Windows 98 Second Edition, and Windows Millennium Edition have reached the end of their support life cycles. It should be a priority for customers who have these operating system versions to migrate to supported versions to prevent potential exposure to vulnerabilities. For more information about the Windows Product Lifecycle, visit the following Microsoft Support Lifecycle Web site. For more information about the extended security update support period for these operating system versions, visit the Microsoft Product Support Services Web site.

Extended security update support for Microsoft Windows NT Workstation 4.0 Service Pack 6a and Windows 2000 Service Pack 2 ended on June 30, 2004. Extended security update support for Microsoft Windows NT Server 4.0 Service Pack 6a ended on December 31, 2004. Extended security update support for Microsoft Windows 2000 Service Pack 3 ended on June 30, 2005. I am still using one of these operating systems; what should I do?
Windows NT Workstation 4.0 Service Pack 6a, Windows NT Server 4.0 Service Pack 6a, Windows 2000 Service Pack 2, and Windows 2000 Service Pack 3 have reached the end of their support life cycles. It should be a priority for customers who have these operating system versions to migrate to supported versions to prevent potential exposure to vulnerabilities. For more information about the Windows Product Lifecycle, visit the following Microsoft Support Lifecycle Web site. For more information about the extended security update support period for these operating system versions, visit the Microsoft Product Support Services Web site.

Customers who require custom support for these products 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, 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 Windows Operating System Product Support Lifecycle FAQ.

Can I use the Microsoft Baseline Security Analyzer (MBSA) to determine whether this update is required?
The following table provides the MBSA detection summary for this security update.
Product MBSA 1.2.1 Enterprise Scanning Tool (EST) MBSA 2.0

Microsoft Windows 2000 Service Pack 4


No


Yes


Yes

Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service Pack 2


No


Yes


Yes

Microsoft Windows XP Professional x64 Edition


No


No


Yes

Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1


No


Yes


Yes

Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with Service Pack 1 for Itanium-based Systems


No


No


Yes

Microsoft Windows Server 2003 x64 Edition family


No


No


Yes

For more information about MBSA, visit the MBSA Web site. For more information about the programs that Microsoft Update and MBSA 2.0 currently do not detect, see Microsoft Knowledge Base Article 895660.

For more detailed information, see Microsoft Knowledge Base Article 910723.

What is the Enterprise Update Scan Tool (EST)?
As part of an ongoing commitment to provide detection tools for bulletin-class security updates, Microsoft delivers a stand-alone detection tool whenever the Microsoft Baseline Security Analyzer (MBSA) and the Office Detection Tool (ODT) cannot detect whether the update is required for an MSRC release cycle. This stand-alone tool is called the Enterprise Update Scan Tool (EST) and is designed for enterprise administrators. When a version of the Enterprise Update Scan Tool is created for a specific bulletin, customers can run the tool from a command line interface (CLI) and view the results of the XML output file. To help customers better utilize the tool, detailed documentation will be provided with the tool. There is also a version of the tool that offers an integrated experience for SMS administrators.

Can I use a version of the Enterprise Update Scan Tool (EST) to determine whether this update is required?
Yes. Microsoft has created a version of the EST that will determine if you have to apply this update. For download links and more information about the version of the EST that is being released this month, see the following Microsoft Web site. SMS customers should review the "Can I use Systems Management Server (SMS) to determine whether this update is required?" FAQ for more information about SMS and EST.

Can I use Systems Management Server (SMS) to determine whether this update is required?
The following table provides the SMS detection summary for this security update.
Product SMS 2.0 SMS 2003

Microsoft Windows 2000 Service Pack 4


Yes (With EST)


Yes

Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service Pack 2


Yes (With EST)


Yes

Microsoft Windows XP Professional x64 Edition


No


Yes

Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1


Yes (With EST)


Yes

Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with Service Pack 1 for Itanium-based Systems


No


Yes

Microsoft Windows Server 2003 x64 Edition family


No


Yes

SMS 2.0 and SMS 2003 Software Update Services (SUS) Feature Pack can use MBSA 1.2.1 for detection and therefore have the same limitation that is listed earlier in this bulletin related to programs that MBSA 1.2.1 does not detect.

For SMS 2.0, the SMS SUS Feature Pack, which includes the Security Update Inventory Tool (SUIT), can be used by SMS to detect security updates. SMS SUIT uses the MBSA 1.2.1 engine for detection. For more information about SUIT, visit the following Microsoft Web site. For more information about the limitations of SUIT, see Microsoft Knowledge Base Article 306460. The SMS SUS Feature Pack also includes the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications.

For SMS 2003, the SMS 2003 Inventory Tool for Microsoft Updates (ITMU) can be used by SMS to detect security updates that are offered by Microsoft Update and that are supported by Windows Server Update Services. For more information about the SMS 2003 ITMU, visit the following Microsoft Web site. SMS 2003 can also use the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications.

For more information about SMS, visit the SMS Web site.

For more detailed information, see Microsoft Knowledge Base Article 910723.
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Vulnerability Details

VML Buffer Overrun Vulnerability - CVE-2006-4868:

A remote code execution vulnerability exists in the Vector Markup Language (VML) implementation in Microsoft Windows. An attacker could exploit the vulnerability by constructing a specially crafted Web page or HTML e-mail that could potentially allow remote code execution if a user visited the Web page or viewed the message. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

Mitigating Factors for VML Buffer Overrun Vulnerability - CVE-2006-4868:


In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to persuade users to visit the Web site, typically by getting them to click a link in an e-mail message or instant messenger message that takes users to the attacker's Web site.


In an e-mail based attack of this exploit, customers who read e-mail in plain text are at less risk from this vulnerability. Instead users would have to either click on a link that would take them to a malicious Web site or open an attachment to be at risk from this vulnerability.


In an e-mail based attack of this exploit, customers who read e-mail using Outlook Express on Windows XP Service Pack 2 and Windows Server 2003 Service Pack 1, are at less risk from this vulnerability because Binary and Script Behaviors is disabled by default in the Restricted sites zone.


An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.


By default, Internet Explorer on Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. This mode mitigates this vulnerability in Windows Server 2003 Service Pack 1 because Binary and Script Behaviors is disabled by default in the Internet zone.


By default, Internet Explorer on Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. This mode mitigates this vulnerability in the e-mail vector for Outlook Express because reading e-mail messages in plain text is the default configuration. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.
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Workarounds for VML Buffer Overrun Vulnerability - CVE-2006-4868:

Microsoft has tested the following workarounds. Although these workarounds will not correct the underlying vulnerability, they help block known attack vectors. When a workaround reduces functionality, it is identified in the following section.


Unregister VGX.DLL

1.


Click Start, click Run, type "%SystemRoot%\System32\regsvr32.exe" -u "%CommonProgramFiles%\Microsoft Shared\VGX\vgx.dll", and then click OK.

2.


A dialog box appears to confirm that the un-registration process has succeeded. Click OK to close the dialog box.

Impact of Workaround: Applications that render VML will no longer do so once vgx.dll has been unregistered.

This security update does not automatically re-register vgx.dll so any applications that render VML will no longer do so until vgx.dll has been re-registered. To re-register vgx.dll follow these steps:

1.


Click Start, click Run, type "%SystemRoot%\System32\regsvr32.exe" "%CommonProgramFiles%\Microsoft Shared\VGX\vgx.dll", and then click OK.

2.


A dialog box appears to confirm that the registration process has succeeded. Click OK to close the dialog box.


Modify the Access Control List on VGX.DLL to be more restrictive

Applying this workaround may cause the installation of security updates provided with this security bulletin to fail:

To modify the Access Control List (ACL) on vgx.dll to be more restrictive, follow these steps:

1.


Click Start, click Run, type "cmd" (without the quotation marks), and then click OK.

2.


Type the following command at a command prompt make a note of the current ACL’s that are on the file (including inheritance settings) for future reference to undo this modification:

cacls "%CommonProgramFiles%\Microsoft Shared\VGX\vgx.dll"

3.


Type the following command at a command prompt to deny the ‘everyone’ group access to this file:

echo y| cacls "%CommonProgramFiles%\Microsoft Shared\VGX\vgx.dll" /d everyone

4.


Close Internet Explorer, and reopen it for the changes to take effect.

Impact of Workaround: Applications and Web sites that render VML may no longer display or function correctly.

Before this security update can be installed, this workaround must be reverted to the previous ACL configuration for vgx.dll. To revert to the previous vgx.dll ACL’s follow these steps:

1.


Click Start, click Run, type "cmd" (without the quotation marks), and then click OK.

2.


To revert to the previous ACL configuration for vgx.dll, type the following command and replace previous with the ACL’s recorded in step 2 of this workaround:

echo y| cacls "%CommonProgramFiles%\Microsoft Shared\VGX\vgx.dll" /g previous

3.


Close Internet Explorer, and reopen it for the changes to take effect.


Configure Internet Explorer 6 for Microsoft Windows XP Service Pack 2 to disable Binary and Script Behaviors in the Internet and Local Intranet security zone

You can help protect against this vulnerability by changing your settings to disable binary and script behaviors in the Internet and Local intranet security zone. To do this, follow these steps:

1.


In Internet Explorer, click Internet Options on the Tools menu.

2.


Click the Security tab.

3.


Click Internet, and then click Custom Level.

4.


Under Settings, in the ActiveX controls and plug-ins section, under Binary and Script Behaviors, click Disable, and then click OK.

5.


Click Local intranet, and then click Custom Level.

6.


Under Settings, in the ActiveX controls and plug-ins section, under Binary and Script Behaviors, click Disable, and then click OK.

7.


Click OK two times to return to Internet Explorer.

Impact of Workaround: Disabling binary and script behaviors in the Internet and Local intranet security zones may cause some Web sites that rely on VML to not function correctly.


Read e-mail messages in plain text format if you are using Outlook 2002 or a later version, or Outlook Express 6 SP1 or a later version, to help protect yourself from the HTML e-mail attack vector

Microsoft Outlook 2002 users who have applied Office XP Service Pack 1 or a later version and Microsoft Outlook Express 6 users who have applied Internet Explorer 6 Service Pack 1 or a later version can enable this setting and view e-mail messages that are not digitally signed or e-mail messages that are not encrypted in plain text only.

Digitally signed e-mail messages or encrypted e-mail messages are not affected by the setting and may be read in their original formats. For more information about how to enable this setting in Outlook 2002, see Microsoft Knowledge Base Article 307594.

For information about this setting in Outlook Express 6, see Microsoft Knowledge Base Article 291387.

Impact of Workaround: E-mail messages that are viewed in plain text format will not contain pictures, specialized fonts, animations, or other rich content. Additionally:


The changes are applied to the preview pane and to open messages.


Pictures become attachments so that they are not lost.


Because the message is still in Rich Text or HTML format in the store, the object model (custom code solutions) may behave unexpectedly.


Block VML Vulnerability Traffic with ISA Server

Customers with Microsoft Internet Security and Acceleration (ISA) Server 2004 or 2006 may also block malicious traffic intended to exploit this vulnerability. For more information about how to enable this setting in ISA Server, see Learn How Your ISA Server Helps Block VML Vulnerability Traffic.
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FAQ for VML Buffer Overrun Vulnerability - CVE-2006-4868:

What is the scope of the vulnerability?
This is a remote code execution vulnerability in the Vector Markup Language (VML) implementation in Microsoft Windows. An attacker could exploit the vulnerability by constructing a specially crafted Web page or HTML e-mail that could potentially allow remote code execution if a user visited the Web page or viewed the message.

If a user were logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.

What causes the vulnerability?
An unchecked buffer in the VML implementation in Microsoft Windows.

What is VML?
Vector Markup Language (VML) is an XML-based exchange, editing, and delivery format for high-quality vector graphics on the Web that meets the needs of both productivity users and graphic design professionals. XML is a simple, flexible, and open text-based language that complements HTML. For more information on the VML, see the product documentation.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take complete control of the affected system.

How could an attacker exploit the vulnerability?
In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to persuade users to visit the Web site, typically by getting them to click a link in an e-mail message or instant messenger message that takes users to the attacker's Web site.

In an e-mail based attack of this exploit, customers who read e-mail in plain text are at less risk from this vulnerability. Instead users would have to either click on a link that would take them to a malicious Web site or open an attachment to be at risk from this vulnerability.

Customers who read e-mail in plain text would also be at less risk when using the Outlook or Outlook Express preview panes.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading e-mail messages or is visiting Web sites for any malicious action to occur. Therefore, any systems where e-mail messages are read or where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability. Systems that are not typically used to visit Web sites, such as most server systems, are at a reduced risk.

What is the Internet Explorer Enhanced Security Configuration?
Internet Explorer Enhanced Security Configuration is a group of preconfigured Internet Explorer settings that reduce the likelihood of a user or of an administrator downloading and running specially crafted Web content on a server. Internet Explorer Enhanced Security Configuration reduces this risk by modifying many security-related settings. This includes the settings on the Security tab and the Advanced tab in the Internet Options dialog box. Some of the important modifications include the following:


Security level for the Internet zone is set to High. This setting disables scripts, ActiveX controls, Microsoft Java Virtual Machine (MSJVM), and file downloads.


Automatic detection of intranet sites is disabled. This setting assigns all intranet Web sites and all Universal Naming Convention (UNC) paths that are not explicitly listed in the Local intranet zone to the Internet zone.


Install On Demand and non-Microsoft browser extensions are disabled. This setting prevents Web pages from automatically installing components and prevents non-Microsoft extensions from running.


Multimedia content is disabled. This setting prevents music, animations, and video clips from running.

For more information regarding Internet Explorer Enhanced Security Configuration, see the guide, Managing Internet Explorer Enhanced Security Configuration, at the following Web site.

What does the update do?
The update removes the vulnerability by modifying the way that Windows validates the length of data before storing it in the allocated buffer.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
Yes. This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2006-4868.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
Yes. When the security bulletin was released, Microsoft had received information that this vulnerability was being exploited.

Does applying this security update help protect customers from the code that has been published publicly that attempts to exploit this vulnerability?
Yes. This security update addresses the vulnerability that is currently being exploited. The vulnerability that has been addressed has been assigned the Common Vulnerability and Exposure number CVE-2006-4868.

Acknowledgments

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


ISS X-Force for working with Microsoft on the VML Buffer Overrun Vulnerability (CVE-2006-4868).


iDEFENSE for working with Microsoft on the VML Buffer Overrun Vulnerability (CVE-2006-4868).


Dan Hubbard at Websense Security Labs for working with Microsoft on the VML Buffer Overrun Vulnerability (CVE-2006-4868).

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 (September 26, 2006): Bulletin published.

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