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HistoryJun 12, 2007 - 12:00 a.m.

Microsoft Security Bulletin MS07-033 - Critical Cumulative Security Update for Internet Explorer (933566)

2007-06-1200:00:00

vulners.com

Microsoft Security Bulletin MS07-033 - Critical
Cumulative Security Update for Internet Explorer (933566)
Published: June 12, 2007

Version: 1.0
General Information
Executive Summary

This critical security update resolves five privately reported vulnerabilities and one publicly disclosed vulnerability. All but one of these vulnerabilities could allow remote code execution if a user viewed a specially crafted Web page using Internet Explorer. One vulnerability could allow spoofing, and also involves a specially crafted Web page. In all remote code execution cases, 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. For the spoofing case, exploitation requires user interaction.

This is a critical security update for supported releases of Internet Explorer 5.01 and Internet Explorer 6, and most supported releases of Internet Explorer 7. For Internet Explorer 7 for supported versions and editions of Windows Server 2003, this update is rated moderate. For more information, see the subsection, Affected and Non-Affected Software, in this section.

This security update addresses two vulnerabilities by setting the kill bit for COM objects and for the rest, by modifying the way that Internet Explorer handles calls, error conditions, and special features such as Language Pack Installation and Speech Control. For more information about the vulnerabilities, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

Recommendation. Microsoft recommends that customers apply the update immediately.

Known Issues. Microsoft Knowledge Base Article 933566 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues.
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Affected and Non-Affected Software

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

Affected Software
Operating System Component Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by This Update
Internet Explorer 5.01 and Internet Explorer 6 Service Pack 1

Microsoft Windows 2000 Service Pack 4

Microsoft Internet Explorer 5.01 Service Pack 4

Remote Code Execution

Critical

MS07-027

Microsoft Windows 2000 Service Pack 4

Microsoft Internet Explorer 6 Service Pack 1

Remote Code Execution

Critical

MS07-027
Internet Explorer 6

Windows XP Service Pack 2

Microsoft Internet Explorer 6

Remote Code Execution

Critical

MS07-027

Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

Microsoft Internet Explorer 6

Remote Code Execution

Critical

MS07-027

Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Microsoft Internet Explorer 6

Remote Code Execution

Critical

MS07-027

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Microsoft Internet Explorer 6

Remote Code Execution

Critical

MS07-027

Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Microsoft Internet Explorer 6

Remote Code Execution

Critical

MS07-027
Internet Explorer 7

Windows XP Service Pack 2

Windows Internet Explorer 7

Remote Code Execution

Critical

MS07-027

Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

Windows Internet Explorer 7

Remote Code Execution

Critical

MS07-027

Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Windows Internet Explorer 7

Remote Code Execution

Moderate

MS07-027

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Windows Internet Explorer 7

Remote Code Execution

Moderate

MS07-027

Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Windows Internet Explorer 7

Remote Code Execution

Moderate

MS07-027

Windows Vista

Windows Internet Explorer 7

Remote Code Execution

Critical

MS07-027

Windows Vista x64 Edition

Windows Internet Explorer 7

Remote Code Execution

Critical

MS07-027
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Frequently Asked Questions (FAQ) Related to This Security Update

What are the known issues that customers may experience when they install this security update?
Microsoft Knowledge Base Article 933566 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues.

Why does this update address several reported security vulnerabilities?
This update addresses several vulnerabilities because the modifications for these issues are located in related files. Instead of having to install several updates that are almost the same, customers need to install this update only.

Does this update contain any security-related changes that are not Internet Explorer specific?
Yes. The changes are listed under the specific vulnerability entry, “Speech Control Memory Corruption Vulnerability CVE-2007-2222” in the next section, Vulnerability Information.

I am using an older release of the software discussed in this security bulletin. What should I do?
The affected software listed in this bulletin have been tested to determine which releases are affected. Other releases are past their support life cycle. To determine the support life cycle for your software release, visit Microsoft Support Lifecycle.

It should be a priority for customers who have older releases of the software to migrate to supported releases to prevent potential exposure to vulnerabilities. For more information about the Windows Product Lifecycle, visit the following Microsoft Support Lifecycle. For more information about the extended security update support period for these software releases, visit the Microsoft Product Support Services Web site.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, visit the Microsoft Worldwide Information Web site, select the country, 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.
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Vulnerability Information

Severity Ratings and Vulnerability Identifiers
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software COM Object Instantiation Memory Corruption Vulnerability – CVE-2007-0218 CSS Tag Memory Corruption Vulnerability – CVE-2007-1750 Language Pack Installation Vulnerability – CVE-2007-3027 Uninitialized Memory Corruption Vulnerability – CVE-2007-1751 Navigation Cancel Page Spoofing Vulnerability – CVE-2007-1752 Speech Control Memory Corruption Vulnerability – CVE-2007-2222 Aggregate Severity Rating
Internet Explorer 5.01 and Internet Explorer 6 Service Pack 1

Internet Explorer 5.01 Service Pack 4 on Microsoft Windows 2000 Service Pack 4

Critical

Remote Code Execution

None

Critical

Remote Code Execution

Critical

Remote Code Execution

None

Critical

Remote Code Execution

Critical

Internet Explorer 6 Service Pack 1 when installed on Microsoft Windows 2000 Service Pack 4

Critical

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

None

Critical

Remote Code Execution

Critical
Internet Explorer 6

Internet Explorer 6 for Windows XP Service Pack 2

Critical

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

None

Critical

Remote Code Execution

Critical

Internet Explorer 6 for Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

Critical

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

None

Critical

Remote Code Execution

Critical

Internet Explorer 6 for Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Moderate

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

Moderate

Remote Code Execution

None

Moderate

Remote Code Execution

Critical

Internet Explorer 6 for Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Moderate

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

Moderate

Remote Code Execution

None

Moderate

Remote Code Execution

Critical

Internet Explorer 6 for Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Moderate

Remote Code Execution

Critical

Remote Code Execution

Critical

Remote Code Execution

Moderate

Remote Code Execution

None

Moderate

Remote Code Execution

Critical
Internet Explorer 7

Internet Explorer 7 for Windows XP Service Pack 2

None

Critical

Remote Code Execution

Critical

Remote Code Execution

Moderate

Spoofing

Critical

Remote Code Execution

Critical

Internet Explorer 7 for Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

None

Critical

Remote Code Execution

Critical

Remote Code Execution

Moderate

Spoofing

Critical

Remote Code Execution

Critical

Internet Explorer 7 for Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

None

Moderate

Remote Code Execution

Moderate

Remote Code Execution

Moderate

Spoofing

Moderate

Remote Code Execution

Moderate

Internet Explorer 7 for Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

None

Moderate

Remote Code Execution

Moderate

Remote Code Execution

Moderate

Spoofing

Moderate

Remote Code Execution

Moderate

Internet Explorer 7 for Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

None

Moderate

Remote Code Execution

Moderate

Remote Code Execution

Moderate

Spoofing

Low

Remote Code Execution

Moderate

Internet Explorer 7 in Windows Vista

None

Critical

Remote Code Execution

Moderate

Spoofing

Critical

Remote Code Execution

Critical

Internet Explorer 7 in Windows Vista x64 Edition

None

Critical

Remote Code Execution

Moderate

Spoofing

Critical

Remote Code Execution

Critical
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COM Object Instantiation Memory Corruption Vulnerability - CVE-2007-0218

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 specially crafted Web page. When a user views the Web page, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2007-0218.

Mitigating Factors for COM Object Instantiation Memory Corruption Vulnerability - CVE-2007-0218

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

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

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, all supported releases of Microsoft Outlook and Microsoft Outlook Express open HTML e-mail messages in the Restricted sites zone. 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. However, if a user clicks on a link within an e-mail they could still be vulnerable to this issue through the Web-based attack scenario.
•

By default, Internet Explorer on Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. This mode sets the security level for the Internet zone to High. This is a mitigating factor for Web sites that you have not added to the Internet Explorer Trusted sites zone. See the FAQ section of this security bulletin for more information about Internet Explorer Enhanced Security Configuration.
•

Internet Explorer 7 is not affected by this vulnerability.
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Workarounds for COM Object Instantiation Memory Corruption Vulnerability - CVE-2007-0218

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

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:

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

Click the Security tab.

Click Internet, and then click Custom Level.

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.

Click Local intranet, and then click Custom Level.

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.

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 the Internet Explorer Trusted sites zone”.

Add sites that you trust to the Internet Explorer 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 the Internet Explorer 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:

In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.

In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.

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.

In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.

Repeat these steps for each site that you want to add to the zone.

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 system. 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 Internet Explorer, follow these steps:

On the Internet Explorer Tools menu, click Internet Options.

In the Internet Options dialog box, click the Security tab, and then click the Internet icon.

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 the Internet Explorer Trusted sites zone”.

Add sites that you trust to the Internet Explorer Trusted sites zone.

To do this, follow these steps:

In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.

In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.

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.

In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.

Repeat these steps for each site that you want to add to the zone.

Click OK two times to accept the changes and return to Internet Explorer.

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.

Note The Class Identifiers and corresponding files where the COM objects are contained are documented provided in the table below
Class Identifier File

{79EAC9E2-BAF9-11CE-8C82-00AA004BA90B}

Urlmon.dll

{79EAC9E3-BAF9-11CE-8C82-00AA004BA90B}

Urlmon.dll

{79EAC9E4-BAF9-11CE-8C82-00AA004BA90B}

Urlmon.dll

{79EAC9E5-BAF9-11CE-8C82-00AA004BA90B}

Urlmon.dll

{79EAC9E6-BAF9-11CE-8C82-00AA004BA90B}

Urlmon.dll

{79EAC9E7-BAF9-11CE-8C82-00AA004BA90B}

Urlmon.dll

{3DD53D40-7B8B-11D0-B013-00AA0059CE02}

Urlmon.dll

Replace {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX} below with the Class Identifiers above.

To set the kill bit for a CLSID with a value of {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}, paste the following text in a text editor such as Notepad. Then, save the file by using the .reg file name extension.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{ XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX }]
"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.
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FAQ for COM Object Instantiation Memory Corruption Vulnerability - CVE-2007-0218

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could take complete control of an affected system remotely. An attacker could then install programs or view, change, or delete data.

What causes the vulnerability?
When Internet Explorer tries to instantiate certain COM objects as ActiveX Controls under certain conditions, 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 specially crafted 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 compromised Web sites and Web sites that accept or host user-provided content or advertisements. These Web sites could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to persuade users to visit the Web site, typically by getting them to click a link in an e-mail message or 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.

I am running Internet Explorer 7. Does this mitigate this vulnerability?
Yes. Internet Explorer 7 is not affected by this vulnerability.

I am running Internet Explorer for Windows Server 2003. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer for Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. Enhanced Security Configuration is a group of preconfigured settings in Internet Explorer that can reduce the likelihood of a user or administrator downloading and running malicious Web content on a server. This is a mitigating factor for Web sites that you have not added to the Internet Explorer Trusted sites zone. See also Managing Internet Explorer Enhanced Security Configuration.

What does the update do?
The update removes the vulnerability by modifying the vulnerable components to better handle the returning of values.

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.
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CSS Tag Memory Corruption Vulnerability - CVE-2007-1750

A remote code execution vulnerability exists in Internet Explorer due to improper handling of a CSS tag. An attacker could exploit the vulnerability by constructing a specially crafted Web page. When a user views the Web page, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2007-1750.

Mitigating Factors for CSS Tag Memory Corruption Vulnerability - CVE-2007-1750

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

By default, all supported releases of Microsoft Outlook and Microsoft Outlook Express open HTML e-mail messages in the Restricted sites zone. The Restricted sites zone helps reduce the number of successful attacks that exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail. However, if a user clicks on a link within an e-mail they could still be vulnerable to this issue through the Web-based attack scenario.

Note It cannot be ruled out that this vulnerability could be used in an exploit without Active Scripting. However, using Active Scripting significantly increases the chances of a successful exploit. As a result, this vulnerability has been given a severity rating of Critical on Windows Server 2003.
•

Internet Explorer 5.01 Service Pack 4 on Windows 2000 Service Pack 4 and Internet Explorer 7 are not affected by this vulnerability.
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Workarounds for CSS Tag Memory Corruption Vulnerability - CVE-2007-1750

Read e-mail messages in plain text format to help protect yourself from the HTML e-mail attack vector

You can help protect yourself against this vulnerability by changing your e-mail settings to read e-mail messages in plain text using Outlook 2002 and later, Outlook Express 6 and later, or Windows Mail. For information in Outlook, search “plain text” in Help and review “Read messages in plain text.” In Outlook Express, search “plain text” in Help and review “Reducing your risk of getting e-mail viruses.” In Windows Mail, search “plain text” in Help and review “Security and privacy in Windows Mail.”

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

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

Pictures become attachments so that they are not lost.
•

Because the message is still in Rich Text or HTML format in the store, the object model (custom code solutions) may behave unexpectedly.
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FAQ for CSS Tag Memory Corruption Vulnerability - CVE-2007-1750

What causes the vulnerability?
Internet Explorer improperly parses a specially crafted CSS tag. As a result, memory may be corrupted in such a way that an attacker could execute arbitrary code in the context of the logged-on user.

How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web site that is designed to exploit the vulnerability and then convince a user to view the Web site. This can also include compromised Web sites and Web sites that accept or host user-provided content or advertisements. These Web sites could contain specially crafted content that could exploit these vulnerabilities. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or in an Instant Messenger message 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 is CSS?
CSS or Cascading Style Sheets is a formatting method for Web pages using HTML.

What does the update do?
The update removes the vulnerability by modifying the way that Internet Explorer handles CSS tags.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued.

Language Pack Installation Vulnerability - CVE-2007-3027

A remote code execution vulnerability exists in Internet Explorer in the way that it handles language pack installation. An attacker could exploit the vulnerability by constructing a specially crafted Web page. When a user views the Web page, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could take complete control of an affected system. User interaction, while expected, is required to exploit this vulnerability.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2007-3027.

Mitigating Factors for Language Pack Installation Vulnerability - CVE-2007-3027

User interaction, while expected, is required to exploit this vulnerability.
•

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

Internet Explorer 7 in Windows Vista and Internet Explorer 7 in Windows Vista x64 Edition are not affected by this vulnerability.
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Workarounds for Language Pack Installation Vulnerability - CVE-2007-3027

Prevent Language Pack Installation

You can prevent language pack installation in Internet Explorer by setting a registry key.

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International]
"W2KLpk"=dword:00000000

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: No language pack(s) will be installed on demand.

How to undo the workaround:

You can enable language pack installation in Internet Explorer by setting a registry key.

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International]
"W2KLpk"=dword:00000001
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FAQ for Language Pack Installation Vulnerability - CVE-2007-3027

What causes the vulnerability?
Internet Explorer may attempt to install multiple language packs in such a way that a race condition may occur. As a result, memory may be corrupted in such a way that an attacker could execute arbitrary code in the context of the logged-on user.

What are language packs on Internet Explorer?
Typically, a Web page may need to download character sets to display the page properly, or to perform a particular task. For example, if you open a Web page that requires Japanese-text display support (Charset=euc-jp), Internet Explorer automatically prompts you to download the Japanese Language Pack component if it is not already installed.

What does the update do?
The update removes the vulnerability by ensuring that a race condition does not occur as a result of attempts to start the installation of multiple language packs.

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

Uninitialized Memory Corruption Vulnerability - CVE-2007-1751

A remote code execution vulnerability exists in the way Internet Explorer accesses an object that has not been correctly initialized or that has been deleted. An attacker could exploit the vulnerability by constructing a specially crafted Web page. When a user views the Web page, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2007-1751.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2007-1751

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

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, the user could still be vulnerable to this issue through the Web-based attack scenario.
•

By default, Internet Explorer on Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. This mode sets the security level for the Internet zone to High. This is a mitigating factor for Web sites that you have not added to the Internet Explorer Trusted sites zone. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.
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Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2007-1751

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:

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

Click the Security tab.

Click Internet, and then click Custom Level.

Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.

Click Local intranet, and then click Custom Level.

Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.

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.

Add sites that you trust to the Internet Explorer Trusted sites zone

To do this, follow these steps:

In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.

In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.

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.

In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.

Repeat these steps for each site that you want to add to the zone.

Click OK two times to accept the changes and return to Internet Explorer.

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 the Internet Explorer Trusted sites zone”.
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Set Internet and Local intranet security zone settings to “High” to prompt before running ActiveX Controls and Active Scripting in these zones

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

On the Internet Explorer Tools menu, click Internet Options.

In the Internet Options dialog box, click the Security tab, and then click the Internet icon.

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.

Add sites that you trust to the Internet Explorer Trusted sites zone

To do this, follow these steps:

In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.

In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.

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.

In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.

Repeat these steps for each site that you want to add to the zone.

Click OK two times to accept the changes and return to Internet Explorer.

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 the Internet Explorer Trusted sites zone”.
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FAQ for Uninitialized Memory Corruption Vulnerability - CVE-2007-1751

What causes the vulnerability?
Internet Explorer attempts to access an object which has not been initialized or has been deleted. As a result, memory may be corrupted in such a way that an attacker could execute arbitrary code in the context of the logged-on user.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited these vulnerabilities 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 specially crafted Web site that is designed to exploit these vulnerabilities through Internet Explorer and then convince a user to visit the Web site. This can also include compromised Web sites and Web sites that accept or host user-provided content or advertisements. These Web sites could contain specially crafted content that could exploit these vulnerabilities. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or in an Instant Messenger message 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 be logged on and visit 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 these vulnerabilities.

What does the update do?
The update removes the vulnerability by modifying the way that Internet Explorer handles errors when calls are made to objects that are no longer initialized.

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

Navigation Cancel Page Spoofing Vulnerability - CVE-2007-1752

A spoofing vulnerability exists in Internet Explorer that could allow an attacker to display spoofed content in the Navigation canceled page. An attacker could exploit the vulnerability by constructing a specially crafted Web page. When a user views the Web page, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2007-1752.

Mitigating Factors for Navigation Cancel Page Spoofing Vulnerability - CVE-2007-1752

User interaction, while expected, is required to exploit this vulnerability.
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In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker's Web site.
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Internet Explorer 5.01 Service Pack 4 on Windows 2000 Service Pack 4, Internet Explorer 6 Service Pack 1 when installed on Windows 2000 Service Pack 4, and Internet Explorer 6 are not affected by this vulnerability.
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Workarounds for Navigation Cancel Page Spoofing Vulnerability - CVE-2007-1752

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

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

Click the Security tab.

Click Internet, and then click Custom Level.

Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.

Click Local intranet, and then click Custom Level.

Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.

Click OK two times to return to Internet Explorer.

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 the Internet Explorer Trusted sites zone”.

Add sites that you trust to the Internet Explorer Trusted sites zone

After you set Internet Explorer to require a prompt before it runs ActiveX controls or Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to the Internet Explorer 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:

In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.

In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.

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.

In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.

Repeat these steps for each site that you want to add to the zone.

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 system. Two in particular that you may want to add are *.windowsupdate.microsoft.com and *.update.microsoft.com. These are the sites that will host the update, and it requires an ActiveX Control to install the update.
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FAQ for Navigation Cancel Page Spoofing Vulnerability - CVE-2007-1752

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.

What causes the vulnerability?
Internet Explorer incorrectly allows the modification of the navigation cancel page. As a result, an attacker could modify a URL which is otherwise trusted by a user.

How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web site, which is designed to exploit the vulnerability, and then convince a user to view the Web site. This can also include compromised Web sites and Web sites that accept or host user-provided content or advertisements. These Web sites could contain specially crafted content that could exploit these vulnerabilities. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or in an Instant Messenger message 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 click on a URL 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 the “Navigation to the webpage was canceled” page so no attempt can be made to modify it by script.

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-2007-1752.

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-2007-1752.
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Speech Control Memory Corruption Vulnerability - CVE-2007-2222

A remote code execution vulnerability exists in a component of Microsoft Speech API 4. An attacker could exploit the vulnerability by constructing a specially crafted Web page. When a user views the Web page, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2007-2222.

Mitigating Factors for Speech Control Memory Corruption Vulnerability - CVE-2007-2222

In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability In addition, compromised Web sites and Web sites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail or Instant Messenger message that takes users to the attacker's Web site.
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Workarounds for Speech Control Memory Corruption Vulnerability - CVE-2007-2222

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.

Note The Class Identifiers and corresponding files where the COM objects are contained are documented under “What does the update do?” in the “FAQ for Speech Control Memory Corruption Vulnerability - CVE-2007-2222” section. Replace {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX} below with the Class Identifiers found in this section.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{ XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX }]
"Compatibility Flags"=dword:00000400

Group Policy collection
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What is Group Policy Object Editor?
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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 object is not intended to be used in Internet Explorer.
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FAQ for Speech Control Memory Corruption Vulnerability - CVE-2007-2222

What causes the vulnerability?
When the ActiveX object is used in Internet Explorer, the object may corrupt the system state in such a way that an attacker could execute arbitrary code.

How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web site that is designed to exploit this vulnerability through Internet Explorer and then convince a user to view the Web site. This can also include compromised Web sites and Web sites that accept or host user-provided content or advertisements. These Web sites could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince 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 is Microsoft Speech?
Microsoft Speech is a technology for speech-based interaction with Windows-based computers. Microsoft Speech SDKs provide continuous speech recognition and text-to-speech engines, tools, sample source code, and information needed for developing speech-enabled applications for Windows.

What does the update do?
This update sets the kill bit for a list of Class Identifier (CLSIDs).

The Class Identifies and corresponding files are as follows:
Class Identifier File

{4E3D9D1F-0C63-11D1-8BFB-0060081841DE}

Xlisten.dll

{EEE78591-FE22-11D0-8BEF-0060081841DE}

Xvoice.dll

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

Microsoft thanks the following for working with us to help protect customers:
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An anonymous researcher working with iDefense VCP for reporting the COM Object Instantiation Memory Corruption Vulnerability - CVE-2007-0218.
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Tom Cross of ISS for working with Microsoft on the COM Object Instantiation Memory Corruption Vulnerability - CVE-2007-0218.
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An anonymous researcher working with TippingPoint and the Zero Day Initiative for reporting the Language Pack Installation Vulnerability - CVE-2007-3027.
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Sam Thomas working with TippingPoint and the Zero Day Initiative for reporting the Uninitialized Memory Corruption Vulnerability - CVE-2007-1751.
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Will Dorman of CERT/CC for reporting the Speech Control Memory Corruption Vulnerability - CVE-2007-2222.
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cocoruder of Fortinet Security Research for working with Microsoft on the Speech Control Memory Corruption Vulnerability - CVE-2007-2222.

Revisions
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V1.0 (June 12, 2007): Bulletin published.