Security Bulletin

Microsoft Security Bulletin MS06-013 - Critical

Published: April 11, 2006

Version: 1.0

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 several prior security updates. See the frequently asked questions (FAQ) section of this bulletin for the complete list.

Caveats: Microsoft Knowledge Base Article 912812 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues. For more information, see Microsoft Knowledge Base Article 912812.

This security update also replaces the cumulative update for Internet Explorer that was released for Windows XP Service Pack 2, Windows Server 2003 Service Pack 1, Windows XP Professional x64 Edition, Windows Server 2003 x64 Edition family, and Windows Server 2003 with Service Pack 1 for Itanium-based Systems on February 28, 2006. This update was discussed in Microsoft Security Advisory (912945): Non-Security Update for Internet Explorer. For more information about this update, see Microsoft Knowledge Base Article 912945.

Compatibility Patch - To help enterprise customers who need more time to prepare for the ActiveX update changes discussed in Microsoft Knowledge Base Article 912945 and included in Microsoft Security Bulletin MS06-013, Microsoft is releasing a Compatibility Patch on April 11, 2006. As soon as it is deployed, the Compatibility Patch will temporarily return Internet Explorer to the previous functionality for handling ActiveX controls. This Compatibility Patch will function until an Internet Explorer update is released as part of the June update cycle, at which time the changes to the way Internet Explorer handles ActiveX controls will be permanent. This compatibility patch may require an additional restart for systems it is deployed on. For more information, see Microsoft Knowledge Base Article 917425.

Tested Software and Security Update Download Locations:

Affected Software:

• Microsoft Windows 2000 Service Pack 4
• Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service Pack 2
• Microsoft Windows XP Professional x64 Edition
• Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1
• Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with Service Pack 1 for Itanium-based Systems
• Microsoft Windows Server 2003 x64 Edition family
• Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and Microsoft Windows Millennium Edition (ME) - Review the FAQ section of this bulletin for details about these operating systems.

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

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 or on Microsoft Windows XP Service Pack 1 - Download the update
• Internet Explorer 6 for Microsoft Windows XP Service Pack 2 - Download the update
• Internet Explorer 6 for Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1 - Download the update
• Internet Explorer 6 for Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based Systems - Download the update
• Internet Explorer 6 for Microsoft Windows Server 2003 x64 Edition - Download the update
• Internet Explorer 6 for Microsoft Windows XP Professional x64 Edition - Download the update
• Internet Explorer 6 Service Pack 1 on Microsoft Windows 98, on Microsoft Windows 98 SE, or on Microsoft Windows Millennium Edition - Review the FAQ section of this bulletin for details about this version.

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.

Executive Summary:

This update resolves several newly-discovered, publicly and privately reported vulnerabilities. Each vulnerability is documented in its own “Vulnerability Details” section of this bulletin.

If a user is logged on with administrative user rights, an attacker who successfully exploited the most severe of these vulnerabilities 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:

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

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

• The Internet Explorer 6 for Windows XP Professional x64 Edition severity rating is the same as the Internet Explorer 6 for Windows XP Service Pack 2 severity rating.
• The Internet Explorer 6 for Microsoft Windows Server 2003 for Itanium-based Systems and Windows Server 2003 x64 Edition severity rating is the same as the Internet Explorer 6 for Windows Server 2003 severity rating.

What updates does this release replace?
This security update replaces several prior security updates. The two most recent security bulletin IDs and affected operating systems are listed in the following table.

Note This security update also replaces the cumulative update for Internet Explorer that was released for Windows XP Service Pack 2 and Windows Server 2003 Service Pack 1 on February 28, 2006. This update was discussed in Microsoft Security Advisory (912945): Non-Security Update for Internet Explorer. For more information about this update, see Microsoft Knowledge Base Article 912945.

What are the known issues that customers may experience when they install this security update?
Microsoft Knowledge Base Article 912812 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues. For more information, see Microsoft Knowledge Base Article 912812.

Does this update contain any security-related changes to functionality?
Yes. Besides the changes that are listed in the “Vulnerability Details” section of this bulletin and in addition to changes that were introduced in previous Internet Explorer security bulletins, this update introduces the following changes:

• This cumulative security update includes defense in depth improvements so that ActiveX controls get consistent information about their hosting environment regardless of how they are instantiated.
• This cumulative security update also sets the kill bit for two ActiveX controls that are included with Danim.dll and Dxtmsft.dll. These controls have been found to contain security vulnerabilities. To help protect customers who have these controls installed, this update prevents these controls from running in Internet Explorer. It does this by setting the kill bit for these controls. For more information about kill bits, see Microsoft Knowledge Base Article 240797. The class identifiers (CLSIDs) for these ActiveX controls are:
  • 42B07B28-2280-4937-B035-0293FB812781
  • 542FB453-5003-11CF-92A2-00AA00B8A733

Does this update contain any other changes to functionality?
Yes. Besides the changes that are listed in the “Vulnerability Details” section of this bulletin, also included are non-security-related changes that were introduced in previous Internet Explorer bulletins.

This security update also replaces the cumulative update for Internet Explorer that was released for Windows XP Service Pack 2, Windows Server 2003 Service Pack 1, Windows XP Professional x64 Edition, Windows Server 2003 x64 Edition family, and Windows Server 2003 with Service Pack 1 for Itanium-based Systems on February 28, 2006. This update was discussed in Microsoft Security Advisory (912945): Non-Security Update for Internet Explorer. For more information about this update, see Microsoft Knowledge Base Article 912945.

Does this update contain the modifications detailed in Microsoft Security Advisory 912945 - Non-Security Update for Internet Explorer?
Yes, this security update contains the Internet Explorer Active X update previously released and discussed in Microsoft Knowledge Base Article 912945. To help enterprise customers who need more time to prepare for the ActiveX update discussed in Microsoft Knowledge Base Article 912945, Microsoft is releasing a Compatibility Patch. As soon as it is deployed, the Compatibility Patch will temporarily return Internet Explorer to the previous functionality for handling ActiveX controls. This Compatibility Patch will function until an Internet Explorer update is released as part of the June update cycle, at which time the changes to the way Internet Explorer handles ActiveX controls will be permanent. This compatibility patch may require an additional restart for systems it is deployed on. For more information, see Microsoft Knowledge Base Article 917425.

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 malicious 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.

How does the extended support for Windows 98, Windows 98 Second Edition, and Windows Millennium Edition affect the release of security updates for these operating systems?
Microsoft will only release security updates for critical security issues. Non-critical security issues are not offered during this support period. For more information about the Microsoft Support Lifecycle policies for these operating systems, visit the following Web site.

For more information about severity ratings, visit the following Web site.

Are Windows 98, Windows 98 Second Edition, or Windows Millennium Edition critically affected by one or more of the vulnerabilities that are addressed in this security bulletin?
Yes. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition are critically affected by the vulnerabilities that are addressed in this security bulletin. Critical security updates for these platforms are available, are provided as part of this security bulletin, and can be downloaded only from the Microsoft Update Web site or from the Windows Update Web site. For more information about severity ratings, visit the following 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’m 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 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 additional support for Windows NT 4.0 SP6a and Windows 2000 Service Pack 3 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.

Security update support for Microsoft Windows XP 64-Bit Edition Service Pack 1 (Itanium) and Microsoft Windows XP 64-Bit Edition Version 2003 (Itanium) ended on June 30, 2005. I’m still using one of these operating systems, what should I do?
With the release of Windows XP Professional x64 Edition, Microsoft Windows XP 64-Bit Edition Service Pack 1 (Itanium) and Microsoft Windows XP 64-Bit Edition Version 2003 (Itanium) will no longer receive security update support. It should be a priority for customers who have these operating system versions to migrate to supported versions to prevent potential exposure to vulnerabilities. Microsoft will continue to fully support Windows Server 2003 for Itanium-based systems, Windows XP Professional x64 Edition, and Windows Server 2003 x64 Editions for 64-bit computing requirements. Microsoft continues to license and support Windows Server 2003 Enterprise and Datacenter editions for Itanium-based systems, and the 64-bit version of SQL Server 2000 Enterprise Edition. In the future, we will expand Itanium support to Visual Studio 2005, .NET Framework 2005, and SQL Server 2005.

Customers who require additional assistance about this issue must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for information about the available migration 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.

Can I use the Microsoft Baseline Security Analyzer (MBSA) 1.2.1 to determine whether this update is required?
Yes. MBSA 1.2.1 will determine whether this update is required. For more information about MBSA, visit the MBSA Web site.

Can I use the Microsoft Baseline Security Analyzer (MBSA) 2.0 to determine whether this update is required?
Yes. MBSA 2.0 will determine whether this update is required. MBSA 2.0 can detect security updates for products that Microsoft Update supports. For more information about MBSA, visit the MBSA Web site.

Can I use Systems Management Server (SMS) to determine whether this update is required?
Yes. SMS can help detect and deploy this security update.

SMS can use the SMS SUS Feature pack, which includes the Security Update Inventory Tool (SUIT) to detect security updates. SMS SUIT uses the MBSA 1.2.1 engine for detection. Therefore, SMS SUIT has the same limitation listed earlier in this bulletin related to programs that MBSA does not detect.

For more information about the Security Update Inventory Tool, see the following Microsoft Web site. For more information about the limitations of the Security Update Inventory Tool, see Microsoft Knowledge Base Article 306460.

The SMS SUS Feature Pack also includes the Microsoft Office Inventory Tool that detects the required updates for Microsoft Office applications.

SMS can use the SMS 2003 Inventory Tool for Microsoft Updates 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 Inventory Tool for Microsoft Updates, visit the following Microsoft Web site.

However, SMS 2.0 customers and SMS 2003 customers who are not using the Inventory Tool for Microsoft Updates must download and deploy an updated version of the Extended Security Update Inventory Tool to receive full detection and deployment for this update.

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

A remote code execution vulnerability exists in the way Internet Explorer displays a Web page that contains certain unexpected method calls to HTML objects. As a result, system memory may be corrupted in such a way that an attacker could execute arbitrary code if a user visited a malicious Web site. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.

• 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.

• The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario.

  By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.

• 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 because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

Microsoft has tested the following workarounds. While 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.

• Configure Internet Explorer to prompt before running Active Scripting or to disable Active Scripting in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your settings to prompt before running Active Scripting or to disable Active Scripting 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 Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling Active Scripting in the Internet and Local intranet security zones may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly.

Impact of Workaround: There are side effects to prompting before running Active Scripting. Many Web sites that are on the Internet or on an intranet use Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use Active Scripting to provide menus, ordering forms, or even account statements. Prompting before running Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

• Set Internet and Local intranet security zone settings to “High” to prompt before running ActiveX Controls and Active Scripting in these zones

You can help protect against this vulnerability by changing your settings for the Internet security zone to prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

To raise the browsing security level in Microsoft Internet Explorer, follow these steps:

1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

Note If no slider is visible, click Default Level, and then move the slider to High.

Note Setting the level to High may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.

Impact of Workaround: There are side effects to prompting before running ActiveX Controls and Active Scripting. Many Web sites that are on the Internet or on an intranet use ActiveX or Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX Controls or Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
When Internet Explorer displays a Web page that contains certain unexpected method calls to HTML objects, system memory may be corrupted in such a way that an attacker could execute arbitrary code.

Specifically, the public postings discuss a potential behavior in Internet Explorer in the way that HTML objects may handle an unexpected createTextRange() method call to an HTML object. A Web page that is specially crafted to exploit this vulnerability will cause Internet Explorer to fail. As a result of this, system memory may be corrupted in such a way that an attacker could execute arbitrary code.

What is the createTextRange() method?
The createTextRange() method is a dynamic HTML (DHTML) method that is exposed by the DHTML Object Model. For more information about DHTML methods, visit the MSDN Library Web site.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain malicious 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 in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

Could this vulnerability be exploited through e-mail?
This vulnerability could not be exploited automatically through e-mail or while viewing e-mail messages in the preview pane while using Outlook or Outlook Express. Customers would have to click on a link that would take them to a malicious Web site, or open an attachment that could exploit the vulnerability.

What systems are primarily at risk from the vulnerability?
This vulnerability requires a user to be logged on and visiting a Web site for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

Are Windows 98, Windows 98 Second Edition or Windows Millennium Edition critically affected by this vulnerability?
Yes. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition are critically affected by this vulnerability. The security updates are available from the Windows Update Web site. For more information about severity ratings, visit the following Web site.

What does the update do?
The update removes the vulnerability by changing the way that Internet Explorer initializes memory before using it.

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-2006-1359.

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-2006-1359.

A remote code execution vulnerability exists in the way Internet Explorer handles multiple event handlers in an HTML element. An attacker could exploit the vulnerability by constructing a malicious Web page that could potentially allow remote code execution if a user visited the malicious Web site. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.
• 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 the e-mail vector because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

No workarounds have been identified for this vulnerability.

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
When Internet Explorer handles multiple event handlers in an HTML element, system memory may be corrupted in such a way that an attacker could execute arbitrary code.

For example, when Internet Explorer displays a Web page that contains multiple onLoad events in an HTML element, system memory may be corrupted in such a way that an attacker could execute arbitrary code.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain malicious 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 in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading HTML e-mail messages or that a user is logged on and visits a Web site for any malicious action to occur. Therefore, any systems where HTML 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.

Note The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario. It may be possible to exploit this vulnerability without making use of Active Scripting. However, our investigation has shown that this is harder to exploit without the use of Active Scripting.

Are Windows 98, Windows 98 Second Edition or Windows Millennium Edition critically affected by this vulnerability?
Yes. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition are critically affected by this vulnerability. The security updates are available from the Windows Update Web site. For more information about severity ratings, visit the following Web site.

What does the update do?
The update removes the vulnerability by modifying the way that Internet Explorer handles multiple event handlers so that Internet Explorer does not exit in an exploitable way.

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-2006-1245.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had seen examples of proof of concept code published publicly but had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

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 potentially could be exploited by using the published proof of concept code. The vulnerability that has been addressed has been assigned the Common Vulnerability and Exposure number CVE-2006-1245.

A remote code execution vulnerability exists in Internet Explorer. An HTML Application (HTA) can be initiated in a way that bypasses the security control within Internet Explorer. This allows an HTA to execute without Internet Explorer displaying the normal security dialog box. An attacker could exploit the vulnerability by constructing a malicious Web page that could potentially allow remote code execution if a user visited the malicious Web site. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.

• 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.

• The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario.

  By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.

• 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. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

Microsoft has tested the following workarounds. While 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.

• Un-register the Mshta.exe file

To un-register the Mshta.exe file, use the following command:

Click Start, click Run, type ""%windir%\system32\mshta.exe /unregister" (without the quotation marks), and then click OK.

Impact of Workaround: Users will be prompted to select a software to open HTML Applications (.HTA files) with.

To undo this change, re-register Mshta.exe by following the above steps. Replace the text in Step 1 with ""%windir%\system32\mshta.exe /register" (without the quotation marks).

• Modify the Access Control List on the Mshta.exe file

You can help protect against this vulnerability by modifying the Access Control List on the Mshta.exe file. To do this, 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 ACLs that are on the file (including inheritance settings) for future reference to undo this modification:

   cacls %windir%\system32\mshta.exe

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

   cacls %windir%\system32\mshta.exe /d everyone

Impact of Workaround: HTML Applications (.HTA files) will stop working.

• Configure Internet Explorer to prompt before running Active Scripting or disable Active Scripting in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your settings to prompt before running Active Scripting or to disable Active Scripting 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 Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling Active Scripting in the Internet and Local intranet security zones may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly.

Impact of Workaround: There are side effects to prompting before running Active Scripting. Many Web sites that are on the Internet or on an intranet use Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use Active Scripting to provide menus, ordering forms, or even account statements. Prompting before running Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

• Set Internet and Local intranet security zone settings to “High” to prompt before running ActiveX Controls and Active Scripting in these zones

You can help protect against this vulnerability by changing your settings for the Internet security zone to prompt before running ActiveX controls. You can do this by setting your browser security to High.

To raise the browsing security level in Microsoft Internet Explorer, follow these steps:

1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

Note If no slider is visible, click Default Level, and then move the slider to High.

Note Setting the level to High may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.

Impact of Workaround: There are side effects to prompting before running ActiveX Controls and Active Scripting. Many Web sites that are on the Internet or on an intranet use ActiveX or Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX Controls or Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
An HTML Application (HTA) can be initiated in a way that bypasses the security control within Internet Explorer. This allows an HTA to execute without Internet Explorer displaying the normal security dialog box.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain malicious 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 in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires a user to be logged on and visiting a Web site for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

Are Windows 98, Windows 98 Second Edition or Windows Millennium Edition critically affected by this vulnerability?
Yes. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition are critically affected by this vulnerability. The security updates are available from the Windows Update Web site. For more information about severity ratings, visit the following Web site.

What does the update do?
The update removes the vulnerability by changing Internet Explorer so that the appropriate security dialog is displayed.

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 and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

A remote code execution vulnerability exists in the way Internet Explorer handles specially crafted and not valid HTML. An attacker could exploit the vulnerability by constructing a malicious Web page that could potentially allow remote code execution if a user visited the malicious Web site. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.
• 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 the e-mail vector because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.
• This vulnerability does not affect Internet Explorer 6 Service Pack 1 on Windows XP Service Pack 1, Windows 2000 Service Pack 4, Windows 98, Windows 98 Second Edition (SE), or Windows Millennium Edition (ME).

No workarounds have been identified for this vulnerability.

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
When Internet Explorer handles specially crafted and not valid HTML it may corrupt system memory in such a way that an attacker could execute arbitrary code.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain malicious 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 in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading HTML e-mail messages or that a user is logged on and visits a Web site for any malicious action to occur. Therefore, any systems where HTML 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.

What does the update do?
The update removes the vulnerability by modifying the way that Internet Explorer handles the reported specially crafted and not valid HTML.

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 and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

A remote code execution vulnerability exists in the way Internet Explorer instantiates COM objects that are not intended to be instantiated in Internet Explorer. An attacker could exploit the vulnerability by constructing a malicious Web page that could potentially allow remote code execution if a user visited the malicious Web site. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

• Customers who have installed the security update included with Microsoft Security Bulletin MS05-052 or a later security bulletin for Internet Explorer are not at risk from attacks originating from the Internet zone.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.

• 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.

• The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing ActiveX Controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario.

  By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.

• 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. See the FAQ section for this security update for more information about Internet Explorer Enhanced Security Configuration.

Microsoft has tested the following workarounds. While 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.

• Configure Internet Explorer to prompt before running ActiveX Controls or disable ActiveX Controls in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your Internet Explorer settings to prompt before running ActiveX controls. 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 Run ActiveX controls and plug-ins, click Prompt or 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 Run ActiveX controls and plug-ins, click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Impact of Workaround: There are side effects to prompting before running ActiveX controls. Many Web sites that are on the Internet or on an intranet use ActiveX to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX controls is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX controls. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

• Set Internet and Local intranet security zone settings to “High” to prompt before running ActiveX Controls and Active Scripting in these zones

You can help protect against this vulnerability by changing your settings for the Internet security zone to prompt before running ActiveX controls. You can do this by setting your browser security to High.

To raise the browsing security level in Microsoft Internet Explorer, follow these steps:

1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

Note If no slider is visible, click Default Level, and then move the slider to High.

Note Setting the level to High may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.

Impact of Workaround: There are side effects to prompting before running ActiveX controls. Many Web sites that are on the Internet or on an intranet use ActiveX to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX controls is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX controls. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

Prevent COM objects from running in Internet Explorer

You can disable attempts to instantiate a COM object in Internet Explorer by setting the kill bit for the control in the registry.

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

For detailed steps that you can use to prevent a control from running in Internet Explorer, see Microsoft Knowledge Base Article 240797. Follow these steps in this article to create a Compatibility Flags value in the registry to prevent a COM object from being instantiated in Internet Explorer.

For example, to set the kill bit for a CLSID in the Mdt2gddr.dll, file that is included in this security update, paste the following text in a text editor such as Notepad. Then, save the file by using the .reg file name extension.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{1F7DD4F2-CAC3-11D0-A35B-00AA00BDCDFD}] "Compatibility Flags"=dword:00000400

You can apply this .reg file to individual systems by double-clicking it. You can also apply it across domains by using Group Policy. For more information about Group Policy, visit the following Microsoft Web sites:

Group Policy collection

What is Group Policy Object Editor?

Core Group Policy tools and settings

Note You must restart Internet Explorer for your changes to take effect.

Impact of Workaround: There is no impact as long as the COM object is not intended to be used in Internet Explorer.

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
When Internet Explorer tries to instantiate certain COM objects as ActiveX Controls, the COM objects may corrupt the system state in such a way that an attacker could execute arbitrary code.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain malicious 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 in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and visits a Web site for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

Note Customers who have installed the security update included with Microsoft Security Bulletin MS05-052 or a later security bulletin for Internet Explorer are not at risk from attacks originating from the Internet zone.

Are Windows 98, Windows 98 Second Edition or Windows Millennium Edition critically affected by this vulnerability?
Yes. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition are critically affected by this vulnerability. The security updates are available from the Windows Update Web site. For more information about severity ratings, visit the following Web site.

What does the update do?
Because not all COM objects are designed to be accessed through Internet Explorer, this update sets the kill bit for a list of Class Identifiers (CLSIDs) for COM objects that have been found to exhibit similar behavior to the COM object Instantiation Memory Corruption Vulnerability that is addressed in Microsoft Security Bulletin MS05-054. To help protect customers, this update prevents these CLSIDs from being instantiated in Internet Explorer. For more information about kill bits, see Microsoft Knowledge Base Article 240797.

The Class Identifiers and corresponding COM objects are as follows.

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 and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

How does this vulnerability relate to one of the vulnerabilities that are corrected by MS05-054?
Both security bulletins address COM object Instantiation Memory Corruption vulnerabilities. However, this update also addresses new CLSIDs that were not addressed as part of MS05-054. MS05-054 helps protect against exploitation of the CLSIDs that are discussed in that bulletin.

Note Customers who have installed the security update included with Microsoft Security Bulletin MS05-052 or a later security bulletin for Internet Explorer are not at risk from attacks originating from the Internet zone.

A remote code execution vulnerability exists in the way Internet Explorer handles HTML elements that contain a specially crafted tag. An attacker could exploit the vulnerability by constructing a malicious Web page that could potentially allow remote code execution if a user visited the malicious Web site. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.
• 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 the e-mail vector because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.
• This vulnerability does not affect Internet Explorer 5.01 Service Pack 4 on Windows 2000 Service Pack 4.

No workarounds have been identified for this vulnerability.

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
When Internet Explorer handles HTML elements containing a specially crafted tag, it may corrupt system memory in such a way that an attacker could execute arbitrary code.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain malicious 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 in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading HTML e-mail messages or that a user is logged on and visits a Web site for any malicious action to occur. Therefore, any systems where HTML 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.

What does the update do?
The update removes the vulnerability by modifying the way that Internet Explorer handles HTML elements containing the specially crafted tag so that Internet Explorer does not exit in an exploitable way.

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-2006-1188.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had seen examples of proof of concept code published publicly but had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

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 potentially could be exploited by using the published proof of concept code. The vulnerability that has been addressed has been assigned the Common Vulnerability and Exposure number CVE-2006-1188.

A remote code execution vulnerability exists in the way Internet Explorer handles double-byte characters in specially crafted URLs. An attacker could exploit the vulnerability by constructing a malicious Web page that could potentially allow remote code execution if a user visited the malicious Web site. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.

• 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.

• The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario.

  By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.

• 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 because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

• This vulnerability does not affect Internet Explorer 5.01 Service Pack 4 on Windows 2000 Service Pack 4 or Internet Explorer 6 for Windows Server 2003 Service Pack 1.

• This vulnerability only affects systems that use Double-Byte Character Sets. Systems that are affected are Windows language versions that use a Double Byte Character Sets language. Examples of languages that use DBCS are Chinese languages, Japanese, and Korean languages. Customers using other language versions of Windows might also be affected if “Language for non-Unicode programs” has been set to a Double Byte Character Sets language.

No workarounds have been identified for this vulnerability.

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
When Internet Explorer handles double-byte characters in specially crafted URLs it may corrupt system memory in such a way that an attacker could execute arbitrary code.

What are Double-Byte Character Sets?
Double-Byte Character Sets (DBCS) are an expanded 8-bit character set where the smallest unit is a byte. Some characters in a DBCS have a single byte code value and some have a double byte code value. A DBCS can be thought of as the ANSI character set for some Asian versions of Microsoft Windows. For more information, see the product documentation.

How do I know if I am running a DBCS locale?
DBCS can be thought of as the ANSI character set for some Asian versions of Microsoft Windows. Examples of languages that use DBCS are Chinese, Japanese, and Korean languages. For more information about system locales and how to determine the system locale please visit this Microsoft Web site.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take complete control of the affected system. In a Web-based attack scenario, an attacker would host a Web site that exploits this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site. It could also be possible to display malicious Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading HTML e-mail messages or that a user is logged on and visits a Web site for any malicious action to occur. Therefore, any systems where HTML 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.

Are Windows 98, Windows 98 Second Edition or Windows Millennium Edition critically affected by this vulnerability?
Yes. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition are critically affected by this vulnerability. The security updates are available from the Windows Update Web site. For more information about severity ratings, visit the following Web site.

What does the update do?
The update removes the vulnerability by modifying the way that Internet Explorer handles double-byte characters in specially crafted URLs.

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 and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

A vulnerability exists in Internet Explorer in the way it returns IOleClientSite information when an embedded object is dynamically created. An attacker could exploit the vulnerability by constructing a malicious Web page with a dynamically created object. This object would need to make use of the IOleClientSite information returned to make a security related decision. This could potentially allow remote code execution or information disclosure if a user visited the malicious Web site. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.

• 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.

• The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario.

  By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.

• 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. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

• This vulnerability does not affect Internet Explorer 5.01 Service Pack 4 on Windows 2000 Service Pack 4.

Microsoft has tested the following workarounds. While 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.

• Configure Internet Explorer to prompt before running ActiveX Controls or disable ActiveX Controls in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your settings to prompt before running ActiveX Controls or to disable ActiveX Controls 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 Run ActiveX controls and plug-ins, click Prompt or 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 Run ActiveX controls and plug-ins, click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling ActiveX Controls in the Internet and Local intranet security zones may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly.

Impact of Workaround: There are side effects to prompting before running ActiveX Controls. Many Web sites that are on the Internet or on an intranet use ActiveX to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX Controls is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX Controls. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

• Configure Internet Explorer to prompt before running Active Scripting or disable Active Scripting in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your settings to prompt before running Active Scripting or to disable Active Scripting 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 Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling Active Scripting in the Internet and Local intranet security zones may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly.

Impact of Workaround: There are side effects to prompting before running Active Scripting. Many Web sites that are on the Internet or on an intranet use Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use Active Scripting to provide menus, ordering forms, or even account statements. Prompting before running Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

• Set Internet and Local intranet security zone settings to “High” to prompt before running ActiveX Controls and Active Scripting in these zones

You can help protect against this vulnerability by changing your settings for the Internet security zone to prompt before running ActiveX controls. You can do this by setting your browser security to High.

To raise the browsing security level in Microsoft Internet Explorer, follow these steps:

1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

Note If no slider is visible, click Default Level, and then move the slider to High.

Note Setting the level to High may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.

Impact of Workaround: There are side effects to prompting before running ActiveX Controls and Active Scripting. Many Web sites that are on the Internet or on an intranet use ActiveX or Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX Controls or Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

What is the scope of the vulnerability?
A vulnerability exists in Internet Explorer that could potentially allow remote code execution or information disclosure. An attacker who successfully exploited this could at worst remotely 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.

What causes the vulnerability?
Internet Explorer may return erroneous IOleClientSite information when an embedded object is dynamically created. This could allow this object to use the IOleClientSite information returned to make an incorrect security related decision and run in the context of the wrong site or the wrong Internet Explorer security zone.

What is IOleClientSite?
The IOleClientSite interface is the primary means by which an embedded object obtains information about the location and extent of its display site, its moniker, its user interface, and other resources provided by its container. For more information, see the product documentation.

What are Internet Explorer security zones?
Internet Explorer security zones are part of a system that divides online content into categories or zones, based on the trustworthiness of the content. Specific Web domains can be assigned to a zone, depending on how much trust is put in the content of each domain. The zone then restricts the capabilities of the Web content, based on the zone's policy. By default, most Internet domains are treated as part of the Internet zone. By default, the policy of the Internet zone prevents scripts and other active code from accessing resources on the local system.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain malicious 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 in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires a user to be logged on and visiting a Web site for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

What does the update do?
The update removes the vulnerability by modifying Internet Explorer so that it returns the correct IOleClientSite information.

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 and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

An information disclosure vulnerability exists in Internet Explorer because of the way that it handles navigation methods. An attacker could exploit the vulnerability by constructing a malicious Web page that could potentially lead to information disclosure if a user visited a malicious Web site or viewed a specially crafted e-mail message. An attacker who successfully exploited this vulnerability could read cookies or other data from another Internet Explorer domain. However, user interaction is required to exploit this vulnerability.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.

• An attacker who successfully exploited this vulnerability could gain access to read cookies or other data from a system other than that of the attacker’s Web site.

• The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario.

  By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.

• 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 because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

• This vulnerability does not affect the following versions of Windows:

  • Windows 2000 Service Pack 4
  • Windows XP Service Pack 1
  • Windows XP Professional x64 Edition
  • Windows Server 2003
  • Windows Server 2003 for Itanium-based Systems and Windows Server 2003 with Service Pack 1 for Itanium-based Systems
  • Windows Server 2003 x64 Edition
  • Windows 98, Windows 98 Second Edition (SE), and Windows Millennium Edition (ME)

Microsoft has tested the following workarounds. While 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.

• Configure Internet Explorer to prompt before running Active Scripting or disable Active Scripting in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your settings to prompt before running Active Scripting or to disable Active Scripting 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 Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling Active Scripting in the Internet and Local intranet security zones may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly.

Impact of Workaround: There are side effects to prompting before running Active Scripting. Many Web sites that are on the Internet or on an intranet use Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use Active Scripting to provide menus, ordering forms, or even account statements. Prompting before running Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

• Set Internet and Local intranet security zone settings to “High” to prompt before running ActiveX Controls and Active Scripting in these zones

You can help protect against this vulnerability by changing your settings for the Internet security zone to prompt before running ActiveX controls. You can do this by setting your browser security to High.

To raise the browsing security level in Microsoft Internet Explorer, follow these steps:

1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

Note If no slider is visible, click Default Level, and then move the slider to High.

Note Setting the level to High may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.

Impact of Workaround: There are side effects to prompting before running ActiveX Controls and Active Scripting. Many Web sites that are on the Internet or on an intranet use ActiveX or Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX Controls or Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to Internet Explorer's Trusted sites zone”.

Add sites that you trust to Internet Explorer's Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to Internet Explorer's Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet Explorer.

Note Add any sites that you trust not to take malicious action on your computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and “*.update.microsoft.com” (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.

What is the scope of the vulnerability?
This is an information disclosure vulnerability. An attacker could exploit the vulnerability by constructing a malicious Web page that could potentially lead to information disclosure or spoofing if a user visited a malicious Web site. An attacker who successfully exploited this vulnerability could read cookies or other data from another Internet Explorer domain. However, user interaction is required to exploit this vulnerability.

What causes the vulnerability?
Internet Explorer allows script to run in a browser window after a navigation to another site has been performed.

What are Internet Explorer security zones?
Internet Explorer security zones are part of a system that divides online content into categories or zones, based on the trustworthiness of the content. Specific Web domains can be assigned to a zone, depending on how much trust is put in the content of each domain. The zone then restricts the capabilities of the Web content, based on the zone's policy. By default, most Internet domains are treated as part of the Internet zone. By default, the policy of the Internet zone prevents scripts and other active code from accessing resources on the local system.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could read cookies or other data from another security zone or domain in Internet Explorer.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain malicious 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 in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires a user to be logged on and visiting a Web site for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

What does the update do?
The update removes the vulnerability by changing Internet Explorer so that it correctly identifies the domain from which the browser window originated.

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 and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

A spoofing vulnerability exists in Internet Explorer that could allow an attacker to display spoofed content in a browser window. The address bar and other parts of the trust UI has been navigated away from the attacker’s Web site but the content of the window still contains the attacker’s Web page.

• In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's Web site.

• Interacting with the Web page, for instance, by clicking on it, will cause the content to refresh and display the Web site identified by the address bar.

• The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario.

  By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.

• 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. See the FAQ section or this security update for more information about Internet Explorer Enhanced Security Configuration.

No workarounds have been identified for this vulnerability.

What is the scope of the vulnerability?
This is a spoofing vulnerability in Internet Explorer. The vulnerability could allow an attacker to display spoofed content in a browser window. Interacting with the Web page, for instance, by clicking on it, will cause the content to refresh and display the Web site pointed out by the address bar.

What causes the vulnerability?
It is possible to navigate the Internet Explorer address bar and other parts of the trust UI away from the attacker’s Web site but persist the content of the window.

How could an attacker exploit the vulnerability?
An attacker could use this vulnerability to create a Web page that would display a URL of the attacker's choosing in the Address bar, while displaying a different Web site in the browser window. An attacker could use this vulnerability to create a malicious page that spoofs a legitimate site. However, it would not be possible to interact with this same Web site.

What systems are primarily at risk from the vulnerability?
This vulnerability requires a user to be logged on and visiting a Web site for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

What does the update do?
The update removes the vulnerability by not allowing the window content to persist after navigation has occurred.

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 and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

Affected Software:

For information about the specific security update for your affected software, click the appropriate link:

Prerequisites This security update requires Windows Server 2003 or Windows Server 2003 Service Pack 1.

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

Inclusion in Future Service Packs: The update for this issue will be included in a future Service Pack or Update Rollup.

Installation Information

This security update supports the following setup switches.

Note You can combine these switches into one command. For backward compatibility, the security update also supports many of the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841. For more information about the Update.exe installer, visit the Microsoft TechNet Web site.

Deployment Information

To install the security update without any user intervention, use the following command at a command prompt for Windows Server 2003:

Windowsserver2003-kb912812-x86-enu /quiet

Note Use of the /quiet switch will suppress all messages. This includes suppressing failure messages. Administrators should use one of the supported methods to verify the installation was successful when they use the /quiet switch. Administrators should also review the KB912812.log file for any failure messages when they use this switch.

To install the security update without forcing the system to restart, use the following command at a command prompt for Windows Server 2003:

Windowsserver2003-kb912812-x86-enu /norestart

For information about how to deploy this security update by using Software Update Services, visit the Software Update Services Web site. For more information about how to deploy this security update using Windows Server Update Services, visit the Windows Server Update Services Web site. This security update will also be available through the Microsoft Update Web site.

Restart Requirement

You must restart your system after you apply this security update.

Removal Information

To remove this update, use the Add or Remove Programs tool in Control Panel.

System administrators can also use the Spuninst.exe utility to remove this security update. The Spuninst.exe utility is located in the %Windir%\$NTUninstallKB912812$\Spuninst folder.

File Information

The English version of this security update has the file attributes that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Windows Server 2003, Web Edition; Windows Server 2003, Standard Edition; Windows Server 2003, Datacenter Edition; Windows Server 2003, Enterprise Edition; Windows Small Business Server 2003; Windows Server 2003, Web Edition with SP1; Windows Server 2003, Standard Edition with SP1; Windows Server 2003, Enterprise Edition with SP1; Windows Server 2003, Datacenter Edition with SP1; Windows Server 2003 R2, Web Edition; Windows Server 2003 R2, Standard Edition; Windows Server 2003 R2, Datacenter Edition; Windows Server 2003 R2, Enterprise Edition; Windows Small Business Server 2003 R2:

Windows Server, 2003 Enterprise Edition for Itanium-based Systems; Windows Server 2003, Datacenter Edition for Itanium-based Systems; Windows Server 2003, Enterprise Edition with SP1 for Itanium-based Systems; and Windows Server 2003, Datacenter Edition with SP1 for Itanium-based Systems:

Windows Server 2003, Standard x64 Edition; Windows Server 2003, Enterprise x64 Edition; and Windows Server 2003, Datacenter x64 Edition; Windows Server 2003 R2, Standard x64 Edition; Windows Server 2003 R2, Enterprise x64 Edition; and Windows Server 2003 R2, Datacenter x64 Edition:

Notes When you install these security updates, the installer checks to see if one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix. If you have previously installed a hotfix to update one of these files, the installer copies the RTMQFE, SP1QFE, or SP2QFE files to your system. Otherwise, the installer copies the RTMGDR, SP1GDR, or SP2GDR files to your system. Security updates may not contain all variations of these files. For more information about this behavior, see Microsoft Knowledge Base Article 824994.

For more information about the Update.exe installer, visit the Microsoft TechNet Web site.

For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

Verifying that the Update Has Been Applied

• Microsoft Baseline Security Analyzer

To verify that a security update has been applied to an affected system, you can use the Microsoft Baseline Security Analyzer (MBSA) tool. MBSA allows administrators to scan local and remote systems for missing security updates and for common security misconfigurations. For more information about MBSA, visit the Microsoft Baseline Security Analyzer Web site.

• File Version Verification

  Note Because there are several versions of Microsoft Windows, the following steps may be different on your computer. If they are, see your product documentation to complete these steps.

  1. Click Start, and then click Search.

  2. In the Search Results pane, click All files and folders under Search Companion.

  3. In the All or part of the file name box, type a file name from the appropriate file information table, and then click Search.

  4. In the list of files, right-click a file name from the appropriate file information table, and then click Properties.

     Note Depending on the version of the operating system or programs installed, some of the files that are listed in the file information table may not be installed.

  5. On the Version tab, determine the version of the file that is installed on your computer by comparing it to the version that is documented in the appropriate file information table.

     Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

• Registry Key Verification

You may also be able to verify the files that this security update has installed by reviewing the following registry key.

Windows Server 2003, Web Edition; Windows Server 2003, Standard Edition; Windows Server 2003, Datacenter Edition; Windows Server 2003, Enterprise Edition; Windows Small Business Server 2003; Windows Server 2003, Web Edition with SP1; Windows Server 2003, Standard Edition with SP1; Windows Server 2003, Enterprise Edition with SP1; Windows Server 2003, Datacenter Edition with SP1; Windows Server 2003 R2, Web Edition; Windows Server 2003 R2, Standard Edition; Windows Server 2003 R2, Datacenter Edition; Windows Server 2003 R2, Enterprise Edition; Windows Small Business Server 2003 R2; Windows Server 2003, Enterprise Edition for Itanium-based Systems; Windows Server 2003, Datacenter Edition for Itanium-based Systems; Windows Server 2003, Enterprise Edition with SP1 for Itanium-based Systems; Windows Server 2003, Datacenter Edition with SP1 for Itanium-based Systems; Windows Server 2003, Standard x64 Edition; Windows Server 2003, Enterprise x64 Edition; and Windows Server 2003, Datacenter x64 Edition; Windows Server 2003 R2, Standard x64 Edition; Windows Server 2003 R2, Enterprise x64 Edition; and Windows Server 2003 R2, Datacenter x64 Edition:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows Server 2003\SP2\KB912812\Filelist

Note This registry key may not contain a complete list of installed files. Also, this registry key may not be created correctly if an administrator or an OEM integrates or slipstreams the 912812 security update into the Windows installation source files.

This security update requires Microsoft Windows XP Service Pack 2. For more information, see Microsoft Knowledge Base Article 322389.

Note For Windows XP Professional x64, this security update is the same as the Windows Server 2003 x64 Edition security update.

Inclusion in Future Service Packs: The update for this issue will be included in a future Service Pack or Update Rollup.

Installation Information

This security update supports the following setup switches.

Note You can combine these switches into one command. For backward compatibility, the security update also supports the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841. For more information about the Update.exe installer, visit the Microsoft TechNet Web site.

Deployment Information

To install the security update without any user intervention, use the following command at a command prompt for Microsoft Windows XP:

Windowsxp-kb912812-x86-enu /quiet

Note Use of the /quiet switch will suppress all messages. This includes suppressing failure messages. Administrators should use one of the supported methods to verify the installation was successful when they use the /quiet switch. Administrators should also review the KB912812.log file for any failure messages when they use this switch.

To install the security update without forcing the system to restart, use the following command at a command prompt for Windows XP:

Windowsxp-kb912812-x86-enu /norestart

For information about how to deploy this security update by using Software Update Services, visit the Software Update Services Web site. For more information about how to deploy this security update using Windows Server Update Services, visit the Windows Server Update Services Web site. This security update will also be available through the Microsoft Update Web site.

Restart Requirement

You must restart your system after you apply this security update.

Removal Information

To remove this security update, use the Add or Remove Programs tool in Control Panel.

System administrators can also use the Spuninst.exe utility to remove this security update. The Spuninst.exe utility is located in the %Windir%\$NTUninstallKB912812$\Spuninst folder.

File Information

The English version of this security update has the file attributes that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Windows XP Home Edition Service Pack 2, Windows XP Professional Service Pack 2, Windows XP Tablet PC Edition 2005, and Windows XP Media Center Edition 2005:

Windows XP Professional x64:

Notes When you install these security updates, the installer checks to see if one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix. If you have previously installed a hotfix to update one of these files, the installer copies the RTMQFE, SP1QFE, or SP2QFE files to your system. Otherwise, the installer copies the RTMGDR, SP1GDR, or SP2GDR files to your system. Security updates may not contain all variations of these files. For more information about this behavior, see Microsoft Knowledge Base Article 824994.

For more information about the Update.exe installer, visit the Microsoft TechNet Web site.

For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

Verifying that the Update Has Been Applied

• Microsoft Baseline Security Analyzer

To verify that a security update has been applied to an affected system, you can use the Microsoft Baseline Security Analyzer (MBSA) tool. MBSA allows administrators to scan local and remote systems for missing security updates and for common security misconfigurations. For more information about MBSA, visit the Microsoft Baseline Security Analyzer Web site.

• File Version Verification

  Note Because there are several versions of Microsoft Windows, the following steps may be different on your computer. If they are, see your product documentation to complete these steps.

  1. Click Start, and then click Search.
  2. In the Search Results pane, click All files and folders under Search Companion.
  3. In the All or part of the file name box, type a file name from the appropriate file information table, and then click Search.
  4. In the list of files, right-click a file name from the appropriate file information table, and then click Properties. Note Depending on the version of the operating system or programs installed, some of the files that are listed in the file information table may not be installed.
  5. On the Version tab, determine the version of the file that is installed on your computer by comparing it to the version that is documented in the appropriate file information table. Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

• Registry Key Verification

You may also be able to verify the files that this security update has installed by reviewing the following registry keys.

Windows XP Home Edition Service Pack 2, Windows XP Professional Service Pack 2, Windows XP Tablet PC Edition 2005, and Windows XP Media Center Edition 2005:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows XP\SP3\KB912812\Filelist

Windows XP Professional x64 Edition:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows XP Version 2003\SP2\KB912812\Filelist

Note These registry keys may not contain a complete list of installed files. Also, these registry keys may not be created correctly if an administrator or an OEM integrates or slipstreams the 912812 security update into the Windows installation source files.

Prerequisites To install the Internet Explorer 6 Service Pack 1 (SP1) version of this update, you must be running Internet Explorer 6 SP1 (version 6.00.2800.1106) on one of the following versions of Windows:

• Microsoft Windows 2000 Service Pack 4
• Microsoft Small Business Server 2000 Service Pack 1a (SP1a) or Small Business Server 2000 running with Windows 2000 Server Service Pack 4 (SP4).
• Microsoft Windows XP Service Pack 1

The software that is listed 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.

For more information about how to obtain the latest service pack, see Microsoft Knowledge Base Article 260910.

Inclusion in Future Service Packs: The update for this issue may be included in a future Update Rollup.

Installation Information

This security update supports the following setup switches.

Note You can combine these switches into one command. For backward compatibility, the security update also supports the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841. For more information about the Update.exe installer, visit the Microsoft TechNet Web site. For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

Deployment Information

To install the security update without any user intervention, use the following command at a command prompt for Windows XP Service Pack 1:

IE6.0sp1-KB912812-Windows-2000-XP-x86-enu /quiet

Note Use of the /quiet switch will suppress all messages. This includes suppressing failure messages. Administrators should use one of the supported methods to verify the installation was successful when they use the /quiet switch. Administrators should also review the KB912812-IE6SP1-20060322.182418.log file for any failure messages when they use this switch.

To install the security update without forcing the system to restart, use the following command at a command prompt for Windows 2000 Service Pack 4:

IE6.0sp1-KB912812-Windows-2000-XP-x86-enu /norestart

For more information about how to deploy this security update with Software Update Services, visit the Software Update Services Web site. For more information about how to deploy this security update using Windows Server Update Services, visit the Windows Server Update Services Web site. This security update will also be available through the Microsoft Update Web site.

Restart Requirement

You must restart your system after you apply this security update.

Removal Information

To remove this security update, use the Add or Remove Programs tool in Control Panel.

System administrators can also use the Spuninst.exe utility to remove this security update. The Spuninst.exe utility is located in the %Windir%\$NTUninstallKB912812-IE6SP1-20060322.182418$\Spuninst folder.

File Information

The English version of this security update has the file attributes that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Windows XP Home Edition Service Pack 1, Windows XP Professional Service Pack 1, Windows XP Tablet PC Edition, Windows XP Media Center Edition, Windows 2000 Service Pack 4 and Small Business Server 2000:

Notes When you install these security updates, the installer checks to see if one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix. If you have previously installed a hotfix to update one of these files, the installer copies the RTMQFE, SP1QFE, or SP2QFE files to your system. Otherwise, the installer copies the RTMGDR, SP1GDR, or SP2GDR files to your system. Security updates may not contain all variations of these files. For more information about this behavior, see Microsoft Knowledge Base Article 824994.

For more information about the Update.exe installer, visit the Microsoft TechNet Web site.

For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

Verifying that the Update Has Been Applied

• Microsoft Baseline Security Analyzer

To verify that a security update has been applied to an affected system, you can use the Microsoft Baseline Security Analyzer (MBSA) tool. MBSA allows administrators to scan local and remote systems for missing security updates and for common security misconfigurations. For more information about MBSA, visit the Microsoft Baseline Security Analyzer Web site.

• File Version Verification

  Note Because there are several versions of Microsoft Windows, the following steps may be different on your computer. If they are, see your product documentation to complete these steps.

  1. Click Start, and then click Search.

  2. In the Search Results pane, click All files and folders under Search Companion.

  3. In the All or part of the file name box, type a file name from the appropriate file information table, and then click Search.

  4. In the list of files, right-click a file name from the appropriate file information table, and then click Properties.

     Note Depending on the version of the operating system or programs installed, some of the files that are listed in the file information table may not be installed.

  5. On the Version tab, determine the version of the file that is installed on your computer by comparing it to the version that is documented in the appropriate file information table.

     Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

• Registry Key Verification

You may also be able to verify the files that this security update has installed by reviewing the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Internet Explorer 6\SP1\KB912812-IE6SP1-20060322.182418\Filelist

Note This registry key may not contain a complete list of installed files. Also, this registry key may not be created correctly when an administrator or an OEM integrates or slipstreams the 912812 security update into the Windows installation source files.

Prerequisites For Windows 2000, this security update requires Service Pack 4 (SP4). For Small Business Server 2000, this security update requires Small Business Server 2000 Service Pack 1a (SP1a) or Small Business Server 2000 running with Windows 2000 Server Service Pack 4 (SP4).

The software that is listed 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.

For more information about how to obtain the latest service pack, see Microsoft Knowledge Base Article 260910.

Inclusion in Future Service Packs: The update for this issue may be included in a future Update Rollup.

Installation Information

This security update supports the following setup switches.

Note You can combine these switches into one command. For backward compatibility, the security update also supports the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841. For more information about the Update.exe installer, visit the Microsoft TechNet Web site. For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

Deployment Information

To install the security update without any user intervention, use the following command at a command prompt for Windows 2000 Service Pack 4:

IE5.01sp4-KB912812-Windows2000sp4-x86-enu /quiet

Note Use of the /quiet switch will suppress all messages. This includes suppressing failure messages. Administrators should use one of the supported methods to verify the installation was successful when they use the /quiet switch. Administrators should also review the KB912812-IE501SP4-20060322.172831.log file for any failure messages when they use this switch.

To install the security update without forcing the system to restart, use the following command at a command prompt for Windows 2000 Service Pack 4:

IE5.01sp4-KB912812-Windows2000sp4-x86-enu /norestart

For more information about how to deploy this security update with Software Update Services, visit the Software Update Services Web site. For more information about how to deploy this security update using Windows Server Update Services, visit the Windows Server Update Services Web site. This security update will also be available through the Microsoft Update Web site.

Restart Requirement

You must restart your system after you apply this security update.

Removal Information

To remove this security update, use the Add or Remove Programs tool in Control Panel.

System administrators can also use the Spuninst.exe utility to remove this security update. The Spuninst.exe utility is located in the %Windir%\$NTUninstallKB912812-IE501SP4-20060322.172831$\Spuninst folder.

File Information

The English version of this security update has the file attributes that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Windows 2000 Service Pack 4 and Small Business Server 2000:

Verifying that the Update Has Been Applied

• Microsoft Baseline Security Analyzer

To verify that a security update has been applied to an affected system, you can use the Microsoft Baseline Security Analyzer (MBSA) tool. MBSA allows administrators to scan local and remote systems for missing security updates and for common security misconfigurations. For more information about MBSA, visit the Microsoft Baseline Security Analyzer Web site.

• File Version Verification

  Note Because there are several versions of Microsoft Windows, the following steps may be different on your computer. If they are, see your product documentation to complete these steps.

  1. Click Start, and then click Search.

  2. In the Search Results pane, click All files and folders under Search Companion.

  3. In the All or part of the file name box, type a file name from the appropriate file information table, and then click Search.

  4. In the list of files, right-click a file name from the appropriate file information table, and then click Properties.

     Note Depending on the version of the operating system or programs installed, some of the files that are listed in the file information table may not be installed.

  5. On the Version tab, determine the version of the file that is installed on your computer by comparing it to the version that is documented in the appropriate file information table.

     Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

• Registry Key Verification

You may also be able to verify the files that this security update has installed by reviewing the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Internet Explorer 5.01\SP4\KB912812-IE501SP4-20060322.172831\Filelist

Note This registry key may not contain a complete list of installed files. Also, this registry key may not be created correctly when an administrator or an OEM integrates or slipstreams the 912812 security update into the Windows installation source files.

Acknowledgments

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

• Andreas Sandblad of Secunia for reporting the DHTML Method Call Memory Corruption Vulnerability (CVE-2006-1359).
• Jeffrey van der Stad for reporting the HTA Execution Vulnerability (CVE-2006-1388).
• Jan P. Monsch of Compass Security Network Computing AG for reporting the HTML Parsing Vulnerability (CVE-2006-1185).
• Richard M. Smith of Boston Software Forensics for reporting class identifiers documented in the COM Object Instantiation Memory Corruption Vulnerability (CVE-2006-1186).
• Thomas Waldegger for reporting a variant of the HTML Tag Memory Corruption Vulnerability (CVE-2006-1188).
• Sowhat of Nevis Labs for reporting the Double Byte Character Parsing Memory Corruption Vulnerability (CVE-2006-1189).
• Heiko Schultze of SAP for reporting the Script Execution Vulnerability (CVE-2006-1190).
• Will Dormann of CERT/CC reporting the issues in the ActiveX controls included with Danim.dll and Dxtmsft.dll for which kill bits have been set in this security update.

Obtaining Other Security Updates:

Updates for other security issues are available at the following locations:

• Security updates are available in the Microsoft Download Center. You can find them most easily by doing a keyword search for "security_patch."
• Updates for consumer platforms are available at the Microsoft Update Web site.

Support:

• Customers in the U.S. and Canada can receive technical support from Microsoft Product Support Services at 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates.
• 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.

Security Resources:

• The Microsoft TechNet Security Web site provides additional information about security in Microsoft products.
• Microsoft Software Update Services
• Microsoft Windows Server Update Services
• Microsoft Baseline Security Analyzer (MBSA)
• Windows Update
• Microsoft Update
• Windows Update Catalog: For more information about the Windows Update Catalog, see Microsoft Knowledge Base Article 323166.
• Office Update

Software Update Services:

By using Microsoft Software Update Services (SUS), administrators can quickly and reliably deploy the latest critical updates and security updates to Windows 2000 and Windows Server 2003-based servers, and to desktop systems that are running Windows 2000 Professional or Windows XP Professional.

For more information about how to deploy security updates by using Software Update Services, visit the Software Update Services Web site.

Windows Server Update Services:

By using Windows Server Update Services (WSUS), administrators can quickly and reliably deploy the latest critical updates and security updates for Windows 2000 operating systems and later, Office XP and later, Exchange Server 2003, and SQL Server 2000 onto Windows 2000 and later operating systems.

For more information about how to deploy security updates using Windows Server Update Services, visit the Windows Server Update Services Web site.

Systems Management Server:

Microsoft Systems Management Server (SMS) delivers a highly-configurable enterprise solution for managing updates. By using SMS, administrators can identify Windows-based systems that require security updates and can perform controlled deployment of these updates throughout the enterprise with minimal disruption to end users. For more information about how administrators can use SMS 2003 to deploy security updates, visit the SMS 2003 Security Patch Management Web site. SMS 2.0 users can also use Software Updates Service Feature Pack to help deploy security updates. For information about SMS, visit the SMS Web site.

Note SMS uses the Microsoft Baseline Security Analyzer, the Microsoft Office Detection Tool, and the Enterprise Update Scanning Tool to provide broad support for security bulletin update detection and deployment. Some software updates may not be detected by these tools. Administrators can use the inventory capabilities of the SMS in these cases to target updates to specific systems. For more information about this procedure, visit the following Web site. Some security updates require administrative rights following a restart of the system. Administrators can use the Elevated Rights Deployment Tool (available in the SMS 2003 Administration Feature Pack and in the SMS 2.0 Administration Feature Pack) to install these updates.

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 11, 2006): Bulletin published

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