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From:MICROSOFT <secure_(at)_microsoft.com>
Date:13.10.2010
Subject:Microsoft Security Bulletin MS10-071 - Critical Cumulative Security Update for Internet Explorer (2360131)

Microsoft Security Bulletin MS10-071 - Critical
Cumulative Security Update for Internet Explorer (2360131)
Published: October 12, 2010

Version: 1.0
General Information
Executive Summary

This security update resolves seven privately reported vulnerabilities and three publicly disclosed vulnerabilities in Internet Explorer. The most severe vulnerabilities could allow remote code execution if a user views a specially crafted Web page using Internet Explorer. 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.

This security update is rated Critical for Internet Explorer 6, Internet Explorer 7, and Internet Explorer 8 on Windows clients; and Important for Internet Explorer 6, Internet Explorer 7, and Internet Explorer 8 on Windows servers. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses these vulnerabilities by modifying the way that Internet Explorer handles objects in memory, CSS special characters, HTML sanitization, the AutoComplete feature, the Anchor element, and script during certain processes. For more information about the vulnerabilities, see the Frequently Asked Questions (FAQ) subsection under the next section, Vulnerability Information.

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

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

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

Known Issues. None
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Affected and Non-Affected Software

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

Affected Software
Operating System Component Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by This Update
Internet Explorer 6

Windows XP Service Pack 3


Internet Explorer 6


Remote Code Execution


Critical


MS10-053

Windows XP Professional x64 Edition Service Pack 2


Internet Explorer 6


Remote Code Execution


Critical


MS10-053

Windows Server 2003 Service Pack 2


Internet Explorer 6


Remote Code Execution


Important


MS10-053

Windows Server 2003 x64 Edition Service Pack 2


Internet Explorer 6


Remote Code Execution


Important


MS10-053

Windows Server 2003 with SP2 for Itanium-based Systems


Internet Explorer 6


Remote Code Execution


Important


MS10-053
Internet Explorer 7

Windows XP Service Pack 3


Internet Explorer 7


Remote Code Execution


Critical


MS10-053

Windows XP Professional x64 Edition Service Pack 2


Internet Explorer 7


Remote Code Execution


Critical


MS10-053

Windows Server 2003 Service Pack 2


Internet Explorer 7


Remote Code Execution


Important


MS10-053

Windows Server 2003 x64 Edition Service Pack 2


Internet Explorer 7


Remote Code Execution


Important


MS10-053

Windows Server 2003 with SP2 for Itanium-based Systems


Internet Explorer 7


Remote Code Execution


Important


MS10-053

Windows Vista Service Pack 1 and Windows Vista Service Pack 2


Internet Explorer 7


Remote Code Execution


Critical


MS10-053

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


Internet Explorer 7


Remote Code Execution


Critical


MS10-053

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


Internet Explorer 7**


Remote Code Execution


Important


MS10-053

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


Internet Explorer 7**


Remote Code Execution


Important


MS10-053

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


Internet Explorer 7


Remote Code Execution


Important


MS10-053
Internet Explorer 8

Windows XP Service Pack 3


Internet Explorer 8


Remote Code Execution


Critical


MS10-053

Windows XP Professional x64 Edition Service Pack 2


Internet Explorer 8


Remote Code Execution


Critical


MS10-053

Windows Server 2003 Service Pack 2


Internet Explorer 8


Remote Code Execution


Important


MS10-053

Windows Server 2003 x64 Edition Service Pack 2


Internet Explorer 8


Remote Code Execution


Important


MS10-053

Windows Vista Service Pack 1 and Windows Vista Service Pack 2


Internet Explorer 8


Remote Code Execution


Critical


MS10-053

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


Internet Explorer 8


Remote Code Execution


Critical


MS10-053

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


Internet Explorer 8**


Remote Code Execution


Important


MS10-053

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


Internet Explorer 8**


Remote Code Execution


Important


MS10-053

Windows 7 for 32-bit Systems


Internet Explorer 8


Remote Code Execution


Critical


MS10-053

Windows 7 for x64-based Systems


Internet Explorer 8


Remote Code Execution


Critical


MS10-053

Windows Server 2008 R2 for x64-based Systems


Internet Explorer 8**


Remote Code Execution


Important


MS10-053

Windows Server 2008 R2 for Itanium-based Systems


Internet Explorer 8


Remote Code Execution


Important


MS10-053

**Server Core installation not affected. The vulnerabilities addressed by this update do not affect supported editions of Windows Server 2008 or Windows Server 2008 R2 as indicated, when installed using the Server Core installation option. For more information on this installation option, see the TechNet articles, Managing a Server Core Installation and Servicing a Server Core Installation. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008 and Windows Server 2008 R2; see Compare Server Core Installation Options.
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Frequently Asked Questions (FAQ) Related to This Security Update

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

How are the Windows 7 Service Pack 1 Beta and Windows Server 2008 R2 Service Pack 1 Beta releases affected by these vulnerabilities?
Windows 7 Service Pack 1 Beta and Windows Server 2008 R2 Service Pack 1 Beta are affected by the vulnerabilities described in this bulletin. Customers running these beta releases are encouraged to download and apply the update to their systems. Security updates are available from Microsoft Update and Windows Update. The security update is also available for download from the Microsoft Download Center.

How is this security update related to MS10-072?
The HTML Sanitization Vulnerability (CVE-2010-3243) and HTML Sanitization Vulnerability (CVE-2010-3324) described in this bulletin also affect Microsoft SharePoint. However, you may install only the updates that correspond to the software you have installed on your systems. If you have installed Internet Explorer, apply the required updates according to this bulletin. If you have installed Microsoft SharePoint, apply the required updates according to MS10-072.

Why does this update address several reported security vulnerabilities?
This update contains support for several vulnerabilities because the modifications that are required to address 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.

I have selected a default browser other than Internet Explorer. Do I still need to apply this update?
Internet Explorer provides application services and functionality for Windows and third-party programs that are maintained through the Cumulative Security Update for Internet Explorer. Microsoft recommends that customers apply the update immediately. The majority of customers have automatic updating enabled and will not need to take any action as this security update will be downloaded and installed automatically.

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

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

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

Severity Ratings and Vulnerability Identifiers

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the October bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software AutoComplete Information Disclosure Vulnerability - CVE-2010-0808 HTML Sanitization Vulnerability - CVE-2010-3243 HTML Sanitization Vulnerability - CVE-2010-3324 CSS Special Character Information Disclosure Vulnerability - CVE-2010-3325 Uninitialized Memory Corruption Vulnerability - CVE-2010-3326 Anchor Element Information Disclosure Vulnerability - CVE-2010-3327 Uninitialized Memory Corruption Vulnerability - CVE-2010-3328 Uninitialized Memory Corruption Vulnerability - CVE-2010-3329 Cross-Domain Information Disclosure Vulnerability - CVE-2010-3330 Uninitialized Memory Corruption Vulnerability - CVE-2010-3331 Aggregate Severity Rating
Internet Explorer 6

Internet Explorer 6 for Windows XP Service Pack 3


Moderate
Information Disclosure


Not applicable


Not applicable


Important
Information Disclosure


Critical
Remote Code Execution


Moderate
Information Disclosure


Critical
Remote Code Execution


Not applicable


Important
Information Disclosure


Important
Remote Code Execution


Critical

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


Moderate
Information Disclosure


Not applicable


Not applicable


Important
Information Disclosure


Critical
Remote Code Execution


Moderate
Information Disclosure


Critical
Remote Code Execution


Not applicable


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 6 for Windows Server 2003 Service Pack 2


None


Not applicable


Not applicable


Low
Information Disclosure


Moderate
Remote Code Execution


Moderate
Information Disclosure


Moderate
Remote Code Execution


Not applicable


Low
Information Disclosure


Important
Remote Code Execution


Important

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


None


Not applicable


Not applicable


Low
Information Disclosure


Moderate
Remote Code Execution


Moderate
Information Disclosure


Moderate
Remote Code Execution


Not applicable


Low
Information Disclosure


Important
Remote Code Execution


Important

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


None


Not applicable


Not applicable


Low
Information Disclosure


Moderate
Remote Code Execution


Moderate
Information Disclosure


Moderate
Remote Code Execution


Not applicable


Low
Information Disclosure


Important
Remote Code Execution


Important
Internet Explorer 7

Internet Explorer 7 for Windows XP Service Pack 3


Moderate
Information Disclosure


Not applicable


Not applicable


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

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


Moderate
Information Disclosure


Not applicable


Not applicable


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 7 for Windows Server 2003 Service Pack 2


None


Not applicable


Not applicable


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

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


None


Not applicable


Not applicable


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

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


None


Not applicable


Not applicable


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

Internet Explorer 7 in Windows Vista Service Pack 1 and Windows Vista Service Pack 2


Moderate
Information Disclosure


Not applicable


Not applicable


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 7 in Windows Vista x64 Edition Service Pack 1 and Windows Vista x64 Edition Service Pack 2


Moderate
Information Disclosure


Not applicable


Not applicable


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 7 in Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2**


None


Not applicable


Not applicable


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

Internet Explorer 7 in Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2**


None


Not applicable


Not applicable


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

Internet Explorer 7 in Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2


None


Not applicable


Not applicable


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important
Internet Explorer 8

Internet Explorer 8 for Windows XP Service Pack 3


Not applicable


Important
Information Disclosure


Important
Information Disclosure


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 8 for Windows XP Professional x64 Edition Service Pack 2


Not applicable


Important
Information Disclosure


Important
Information Disclosure


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 8 for Windows Server 2003 Service Pack 2


Not applicable


Low
Information Disclosure


Low
Information Disclosure


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

Internet Explorer 8 for Windows Server 2003 x64 Edition Service Pack 2


Not applicable


Low
Information Disclosure


Low
Information Disclosure


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

Internet Explorer 8 in Vista Service Pack 1 and Windows Vista Service Pack 2


Not applicable


Important
Information Disclosure


Important
Information Disclosure


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 8 in Windows Vista x64 Edition Service Pack 1 and Windows Vista x64 Edition Service Pack 2


Not applicable


Important
Information Disclosure


Important
Information Disclosure


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 8 in Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2**


Not applicable


Low
Information Disclosure


Low
Information Disclosure


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

Internet Explorer 8 in Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2**


Not applicable


Low
Information Disclosure


Low
Information Disclosure


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

Internet Explorer 8 in Windows 7 for 32-bit Systems


Not applicable


Important
Information Disclosure


Important
Information Disclosure


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 8 in Windows 7 for x64-based Systems


Not applicable


Important
Information Disclosure


Important
Information Disclosure


Important
Information Disclosure


Not applicable


Moderate
Information Disclosure


Critical
Remote Code Execution


Important
Remote Code Execution


Important
Information Disclosure


Important
Remote Code Execution


Critical

Internet Explorer 8 in Windows Server 2008 R2 for x64-based Systems**


Not applicable


Low
Information Disclosure


Low
Information Disclosure


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

Internet Explorer 8 in Windows Server 2008 R2 for Itanium-based Systems


Not applicable


Low
Information Disclosure


Low
Information Disclosure


Low
Information Disclosure


Not applicable


Moderate
Information Disclosure


Moderate
Remote Code Execution


Important
Remote Code Execution


Low
Information Disclosure


Important
Remote Code Execution


Important

**Server Core installation not affected. The vulnerabilities addressed by this update do not affect supported editions of Windows Server 2008 or Windows Server 2008 R2 as indicated, when installed using the Server Core installation option. For more information on this installation option, see the TechNet articles, Managing a Server Core Installation and Servicing a Server Core Installation. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008 and Windows Server 2008 R2; see Compare Server Core Installation Options.
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AutoComplete Information Disclosure Vulnerability - CVE-2010-0808

An information disclosure vulnerability exists that potentially allows form data within Internet Explorer to be captured via the AutoComplete feature. An attacker could exploit the vulnerability by constructing a specially crafted Web page that could allow information disclosure if a user viewed the Web page. An attacker who successfully exploited this vulnerability could capture information previously entered into fields after the AutoComplete feature has been enabled.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0808.

Mitigating Factors for AutoComplete Information Disclosure Vulnerability - CVE-2010-0808

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:


By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 subsection of this vulnerability section for more information about Internet Explorer Enhanced Security Configuration.
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Workarounds for AutoComplete Information Disclosure Vulnerability - CVE-2010-0808

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:


Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones

You can help protect against exploitation of this vulnerability by changing your settings for the Internet security zone to block 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:

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 blocking 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. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such 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 block 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 yourself 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 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.


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 exploitation of 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 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:

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 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 AutoComplete Information Disclosure Vulnerability - CVE-2010-0808

What is the scope of the vulnerability?
This is an information disclosure vulnerability. An attacker who exploited the vulnerability when a user views a Web page could capture content entered into form fields if the AutoComplete feature has been enabled.

What causes the vulnerability?
Internet Explorer allows for automated, scripted instructions to simulate user actions on the AutoComplete feature.

What is the AutoComplete feature?
AutoComplete is a feature in Internet Explorer that helps users quickly enter information in form fields. For more information, see the MSDN article, Using AutoComplete in HTML Forms.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could potentially capture data previously entered into forms in the browser. The AutoComplete feature is disabled by default.

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. The attacker could also take advantage of 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 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 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 addresses the vulnerability by modifying the AutoComplete feature within Internet Explorer.

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-2010-0808.

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.

I am running Internet Explorer for Windows Server 2003 or Windows Server 2008. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 specially crafted 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.
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HTML Sanitization Vulnerability - CVE-2010-3243

An information disclosure vulnerability exists in the way that the toStaticHTML API sanitizes HTML, that could allow an attacker to perform cross-site scripting attacks and run script in the security context of the logged-on user. An attacker who successfully exploited this vulnerability could execute a cross-site scripting attack on the user, allowing the attacker to execute script in the user's security context against a site that is using the toStaticHTML API.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3243.

Mitigating Factors for HTML Sanitization Vulnerability - CVE-2010-3243

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:


By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 subsection of this vulnerability section for more information about Internet Explorer Enhanced Security Configuration.


Only Web sites that is using toStaticHTML may potentially be affected.
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Workarounds for HTML Sanitization Vulnerability - CVE-2010-3243

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:


Read e-mails in plain text

To help protect yourself from the e-mail attack vector, read e-mail messages in plain text format.

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

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

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

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


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


Pictures become attachments so that they are not lost.


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


Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones

You can help protect against exploitation of this vulnerability by changing your settings for the Internet security zone to block 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:

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 blocking 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. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such 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 block 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 yourself 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 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.


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 exploitation of 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 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:

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 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 HTML Sanitization Vulnerability - CVE-2010-3243

What is the scope of the vulnerability?
This is an information disclosure vulnerability. An attacker who exploited the vulnerability when a user views a Web page that uses the toStaticHTML API may execute a cross-site scripting attack on the user.

What causes the vulnerability?
The vulnerability exists in the way that Internet Explorer handles content using specific strings when sanitizing HTML.

What is the toStaticHTML API?
The toStaticHTML API can be used to remove event attributes and script from user input before display as HTML. For more information, please see the MSDN Library article, toStaticHTML Method.

Is this vulnerability related to CVE-2010-3243 in MS10-072, Vulnerabilities in toStaticHTML Could Allow Information Disclosure?
Yes, the HTML Sanitization Vulnerability, CVE-2010-4243, also affects Microsoft SharePoint.

Are both updates necessary to be installed to be protected from the vulnerability?
No, each update addresses a separate application. Only the update that corresponds with software running on your system needs to be applied.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability, when a user is viewing HTML on a Web site that has not been properly sanitized by Internet Explorer, could execute script in the user's security context against a site.

How could an attacker exploit the vulnerability?
To exploit this vulnerability, an attacker must have the ability to submit a specially crafted script to a target site. Due to the vulnerability, in specific situations the specially crafted script is not properly sanitized using toStaticHTML, and subsequently this could lead to attacker-supplied script being run in the security context of a user who views the malicious content on the Web site.

For cross-site scripting attacks, this vulnerability requires that a user be visiting a compromised Web site for any malicious action to occur. For instance, after an attacker has successfully submitted specially crafted script to the target site, any Web page on that site that contains the specially crafted script is a potential vector for persistent cross-site scripting attacks. When a user visits a Web page that contains the specially crafted script, the script could be run in the security context of the user on the site.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user 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.

I am running Internet Explorer for Windows Server 2003 or Windows Server 2008. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 specially crafted 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 addresses the vulnerability by modifying the way that Internet Explorer handles HTML sanitization using toStaticHTML.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
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HTML Sanitization Vulnerability - CVE-2010-3324

An information disclosure vulnerability exists in the way that the toStaticHTML API sanitizes HTML, that could allow an attacker to perform cross-site scripting attacks and run script in the security context of the logged-on user. An attacker who successfully exploited this vulnerability could execute a cross-site scripting attack on the user, allowing the attacker to execute script in the user's security context against a site that is using the toStaticHTML API.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3324.

Mitigating Factors for HTML Sanitization Vulnerability - CVE-2010-3324

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:


By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 subsection of this vulnerability section for more information about Internet Explorer Enhanced Security Configuration.


Only Web sites that is using toStaticHTML may potentially be affected.
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Workarounds for HTML Sanitization Vulnerability - CVE-2010-3324

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:


Read e-mails in plain text

To help protect yourself from the e-mail attack vector, read e-mail messages in plain text format.

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

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

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

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


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


Pictures become attachments so that they are not lost.


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


Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones

You can help protect against exploitation of this vulnerability by changing your settings for the Internet security zone to block 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:

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 blocking 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. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such 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 block 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 yourself 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 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.


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 exploitation of 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 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:

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 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.
Top of sectionTop of section

FAQ for HTML Sanitization Vulnerability - CVE-2010-3324

What is the scope of the vulnerability?
This is an information disclosure vulnerability. An attacker who exploited the vulnerability when a user views a Web page that uses the toStaticHTML API may execute a cross-site scripting attack on the user.

What causes the vulnerability?
The vulnerability exists in the way that Internet Explorer handles content using specific strings when sanitizing HTML.

What is the toStaticHTML API?
The toStaticHTML API can be used to remove event attributes and script from user input before display as HTML. For more information, please see the MSDN Library article, toStaticHTML Method.

Is this vulnerability related to CVE-2010-3324 in MS10-072, Vulnerabilities in toStaticHTML Could Allow Information Disclosure?
Yes, the HTML Sanitization Vulnerability, CVE-2010-3324, also affects Microsoft SharePoint.

Are both updates necessary to be installed to be protected from the vulnerability?
No, each update addresses a separate application. Only the update that corresponds with software running on your system needs to be applied.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability, when a user is viewing HTML on a Web site that has not been properly sanitized by Internet Explorer, could execute script in the user's security context against the site.

How could an attacker exploit the vulnerability?
To exploit this vulnerability, an attacker must have the ability to submit a specially crafted script to a target site. Due to the vulnerability, in specific situations the specially crafted script is not properly sanitized using toStaticHTML, and subsequently this could lead to attacker-supplied script being run in the security context of a user who views the malicious content on the Web site.

For cross-site scripting attacks, this vulnerability requires that a user be visiting a compromised Web site for any malicious action to occur. For instance, after an attacker has successfully submitted specially crafted script to the target site, any Web page on that site that contains the specially crafted script is a potential vector for persistent cross-site scripting attacks. When a user visits a Web page that contains the specially crafted script, the script could be run in the security context of the user on the site.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user 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 addresses the vulnerability by modifying the way that Internet Explorer handles HTML sanitization using toStaticHTML.

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-2010-3324.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
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CSS Special Character Information Disclosure Vulnerability - CVE-2010-3325

An information disclosure vulnerability exists in the way that Internet Explorer processes CSS special characters. An attacker could exploit the vulnerability by constructing a specially crafted Web page that could allow information disclosure if a user viewed the Web page. An attacker who successfully exploited this vulnerability could view content from another domain or Internet Explorer zone.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3325.

Mitigating Factors for CSS Special Character Information Disclosure Vulnerability - CVE-2010-3325

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 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.


By default, all supported versions of Microsoft Outlook, Microsoft Outlook Express, and Windows Mail open HTML e-mail messages in the Restricted sites zone, which disables script and ActiveX controls, removing the risk of an attacker being able to use this vulnerability to execute malicious code. If a user clicks a link in an e-mail message, the user could still be vulnerable to exploitation of this vulnerability through the Web-based attack scenario.


By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 subsection of this vulnerability section for more information about Internet Explorer Enhanced Security Configuration.
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Workarounds for CSS Special Character Information Disclosure Vulnerability - CVE-2010-3325

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:


Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones

You can help protect against exploitation of this vulnerability by changing your settings for the Internet security zone to block 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:

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 blocking 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. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such 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 block 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 yourself 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 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.


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 exploitation of 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 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:

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 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.
Top of sectionTop of section

FAQ for CSS Special Character Information Disclosure Vulnerability - CVE-2010-3325

What is the scope of the vulnerability?
This is an information disclosure vulnerability. An attacker who exploited the vulnerability when a user views a Web page could view content from another domain or Internet Explorer zone other than the domain or zone of the attacker's Web page.

What causes the vulnerability?
Internet Explorer improperly processes CSS special characters, potentially allowing disclosure of sensitive data.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could view content from another domain or Internet Explorer zone.

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. The attacker could also take advantage of 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 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 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.

I am running Internet Explorer for Windows Server 2003 or Windows Server 2008. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 specially crafted 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?
This update addresses the vulnerability by modifying the way that Internet Explorer handles CSS special characters.

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-2010-3325.

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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Uninitialized Memory Corruption Vulnerability - CVE-2010-3326

A remote code execution vulnerability exists in the way that Internet Explorer accesses an object that has not been correctly initialized or 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 gain the same user rights as the logged-on user. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3326.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2010-3326

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 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.


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 versions of Microsoft Outlook, Microsoft Outlook Express, and Windows Mail open HTML e-mail messages in the Restricted sites zone, which disables script and ActiveX controls, removing the risk of an attacker being able to use this vulnerability to execute malicious code. If a user clicks a link in an e-mail message, the user could still be vulnerable to exploitation of this vulnerability through the Web-based attack scenario.


By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 subsection of this vulnerability section for more information about Internet Explorer Enhanced Security Configuration.
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Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2010-3326

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:


Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones

You can help protect against exploitation of this vulnerability by changing your settings for the Internet security zone to block 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:

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 blocking 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. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such 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 block 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 yourself 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 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.


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 exploitation of 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 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:

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 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 Uninitialized Memory Corruption Vulnerability - CVE-2010-3326

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on 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.

What causes the vulnerability?
When Internet Explorer attempts to access an object that has not been initialized or has been deleted, it may corrupt memory 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 this vulnerability could gain the same user rights as a logged-on user. If the user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

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. An attacker could also embed an ActiveX control marked "safe for initialization" in an application or Microsoft Office document that hosts the IE rendering engine. The attacker could also take advantage of 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 view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by clicking a link in an e-mail message or in an Instant Messenger message that takes users to the attacker's Web site, or by opening an attachment sent through e-mail.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user 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.

I am running Internet Explorer for Windows Server 2003 or Windows Server 2008. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 specially crafted 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 addresses the vulnerability by modifying the way that Internet Explorer handles objects in memory.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
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Anchor Element Information Disclosure Vulnerability - CVE-2010-3327

An information disclosure vulnerability exists in the way that Internet Explorer improperly handles the Anchor element. This behavior occurs during user operation when the Anchor element is not removed during content pasting and editing, potentially revealing personally identifiable information intended for deletion.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3327.

Mitigating Factors for Anchor Element Information Disclosure Vulnerability - CVE-2010-3327

Microsoft has not identified any mitigating factors for this vulnerability.
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Workarounds for Anchor Element Information Disclosure Vulnerability - CVE-2010-3327

Microsoft has not identified any workarounds for this vulnerability.
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FAQ for Anchor Element Information Disclosure Vulnerability - CVE-2010-3327

What is the scope of the vulnerability?
This is an information disclosure vulnerability. Potentially deleted information will remain in HTML content.

What causes the vulnerability?
During specific user operation, the Anchor element is not removed from the editable HTML element.

How could an attacker exploit the vulnerability?
This issue is not an exploitable vulnerability. Instead, it potentially exposes previously deleted content during user operation.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user be logged on and utilizing the browser for HTML content creation. 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 addresses the vulnerability by modifying the way that Internet Explorer handles the Anchor element.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
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Uninitialized Memory Corruption Vulnerability - CVE-2010-3328

A remote code execution vulnerability exists in the way that Internet Explorer accesses an object that has not been correctly initialized or 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 gain the same user rights as the logged-on user. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3328.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2010-3328

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 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.


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 versions of Microsoft Outlook, Microsoft Outlook Express, and Windows Mail open HTML e-mail messages in the Restricted sites zone, which disables script and ActiveX controls, removing the risk of an attacker being able to use this vulnerability to execute malicious code. If a user clicks a link in an e-mail message, the user could still be vulnerable to exploitation of this vulnerability through the Web-based attack scenario.


By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 subsection of this vulnerability section for more information about Internet Explorer Enhanced Security Configuration.
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Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2010-3328

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:


Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones

You can help protect against exploitation of this vulnerability by changing your settings for the Internet security zone to block 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:

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 blocking 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. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such 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 block 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 yourself 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 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.


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 exploitation of 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 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:

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 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.
Top of sectionTop of section

FAQ for Uninitialized Memory Corruption Vulnerability - CVE-2010-3328

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on 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.

What causes the vulnerability?
When Internet Explorer attempts to access an object that has not been initialized or has been deleted, it may corrupt memory 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 this vulnerability could gain the same user rights as a logged-on user. If the user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

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. An attacker could also embed an ActiveX control marked "safe for initialization" in an application or Microsoft Office document that hosts the IE rendering engine. The attacker could also take advantage of 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 view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by clicking a link in an e-mail message or in an Instant Messenger message that takes users to the attacker's Web site, or by opening an attachment sent through e-mail.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user 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.

I am running Internet Explorer for Windows Server 2003 or Windows Server 2008. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 specially crafted 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 addresses the vulnerability by modifying the way that Internet Explorer handles objects in memory.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
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Uninitialized Memory Corruption Vulnerability - CVE-2010-3329

A remote code execution vulnerability exists in the way that Internet Explorer accesses an object that has not been correctly initialized or has been deleted when a document in an HTML format is opened in Microsoft Word. An attacker could exploit the vulnerability by convincing the user to open a malicious Word document. When a user closes the document, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on user. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3329.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2010-3329

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:


The vulnerability cannot be exploited automatically through e-mail. For an attack to be successful, a user must open an attachment that is sent in an e-mail message.


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.
Top of sectionTop of section

Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2010-3329

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:


Prevent COM objects from running in Internet Explorer

You can disable attempts to instantiate a HtmlDlgHelper Class 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 the steps in this article to create a Compatibility Flags value in the registry to prevent a COM object from being instantiated in Internet Explorer.

To set the kill bit for a CLSID with a value of {3050f4e1-98b5-11cf-bb82-00aa00bdce0b}, 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\{3050f4e1-98b5-11cf-bb82-00aa00bdce0b}]
"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 object is not intended to be used in Internet Explorer.

How to undo the workaround. Delete the registry keys previously added in implementing this workaround.
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FAQ for Uninitialized Memory Corruption Vulnerability - CVE-2010-3329

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on 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.

What causes the vulnerability?
When Internet Explorer attempts to access an object that has not been initialized or has been deleted when Microsoft Word has been closed, it may corrupt memory 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 this vulnerability could gain the same user rights as a logged-on user. If the user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

How could an attacker exploit the vulnerability?
An attacker can send a user a specially crafted Word document that is designed to exploit this vulnerability through Microsoft Word and convince the user to view the Word document. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by clicking a link in an e-mail message or in an Instant Messenger message that takes users to the attacker's Web site, or by opening an attachment sent through e-mail. This issue cannot be exploited directly through Internet Explorer.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user be logged on and open a malicious Word document for any malicious action to occur. Therefore, any systems where Microsoft Word is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

What does the update do?
The update addresses the vulnerability by modifying the way that Internet Explorer handles objects in memory.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
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Cross-Domain Information Disclosure Vulnerability - CVE-2010-3330

An information disclosure vulnerability exists in Internet Explorer that could allow script to gain access to information in another domain or Internet Explorer zone. An attacker could exploit the vulnerability by constructing a specially crafted Web page that could allow information disclosure if a user viewed the Web page. An attacker who successfully exploited this vulnerability could view content from another domain or Internet Explorer zone.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3330.

Mitigating Factors for Cross-Domain Information Disclosure Vulnerability - CVE-2010-3330

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:


By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 subsection of this vulnerability section for more information about Internet Explorer Enhanced Security Configuration.


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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Workarounds for Cross-Domain Information Disclosure Vulnerability - CVE-2010-3330

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:


Read e-mails in plain text

To help protect yourself from the e-mail attack vector, read e-mail messages in plain text format.

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

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

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

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


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


Pictures become attachments so that they are not lost.


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


Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones

You can help protect against exploitation of this vulnerability by changing your settings for the Internet security zone to block 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:

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 blocking 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. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such 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 block 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 yourself 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 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.


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 exploitation of 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 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:

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 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 Cross-Domain Information Disclosure Vulnerability - CVE-2010-3330

What is the scope of the vulnerability?
This is an information disclosure vulnerability. An attacker who exploited the vulnerability when a user views a Web page could view content from a different domain or Internet Explorer zone other than the domain or zone of the attacker's Web page.

What causes the vulnerability?
During certain processes, Internet Explorer incorrectly allows scripts to access and read content from different domains.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could view content from another domain or Internet Explorer zone.

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. The attacker could also take advantage of 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 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 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.

I am running Internet Explorer for Windows Server 2003 or Windows Server 2008. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 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 specially crafted 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 addresses the vulnerability by modifying the way that Internet Explorer handles script during certain processes.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
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Uninitialized Memory Corruption Vulnerability - CVE-2010-3331

A remote code execution vulnerability exists in the way that Internet Explorer accesses an object that has not been correctly initialized or has been deleted. An attacker could exploit the vulnerability by convincing a user to view a specially crafted Word document. When a user closes the Word document, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on user. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3331.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2010-3331

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:


The vulnerability cannot be exploited automatically through e-mail. For an attack to be successful, a user must open an attachment that is sent in an e-mail message.


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.


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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Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2010-3331

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:


Use Microsoft Office File Block policy to block the opening of HTML documents from unknown or untrusted sources and locations

The following registry scripts can be used to set the File Block policy.

Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

For Office 2003

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.
0\Word\Security\FileOpenBlock]

"HtmlFiles"=dword:00000001

Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

For 2007 Office system

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.
0\Word\Security\FileOpenBlock]

"HtmlFiles"=dword:00000001

Note In order to use 'FileOpenBlock' with the 2007 Microsoft Office system, all of the latest security updates for the 2007 Microsoft Office system must be applied.

Impact of workaround. Users who have configured the File Block policy and have not configured a special "exempt directory" as discussed in Microsoft Knowledge Base Article 922848 will be unable to open Office 2003 files or earlier versions in Office 2003 or 2007 Microsoft Office System.

How to undo the workaround.

For Office 2003

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.
0\Word\Security\FileOpenBlock]

"HtmlFiles"=dword:00000000

For 2007 Office system

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.
0\Word\Security\FileOpenBlock]

"HtmlFiles"=dword:00000000
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FAQ for Uninitialized Memory Corruption Vulnerability - CVE-2010-3331

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on 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.

What causes the vulnerability?
When Internet Explorer attempts to access an object that has not been initialized or has been deleted, it may corrupt memory 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 this vulnerability could gain the same user rights as a logged-on user. If the user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

How could an attacker exploit the vulnerability?
An attacker can send a user a specially crafted Word document that is designed to exploit this vulnerability through Microsoft Word and convince the user to view the Word document. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by clicking a link in an e-mail message or in an Instant Messenger message that takes users to the attacker's Web site, or by opening an attachment sent through e-mail. This issue cannot be exploited directly through Internet Explorer.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user be logged on and opening a malicious Word document for an attack to occur. Therefore, any systems where Microsoft Word is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

What does the update do?
The update addresses the vulnerability by modifying the way that Internet Explorer handles objects in memory.

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

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

Other Information
Acknowledgments

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


Sirdarckcat of Google Inc. for reporting the HTML Sanitization Vulnerability (CVE-2010-3243)


Mario Heiderich for reporting the HTML Sanitization Vulnerability (CVE-2010-3324)


Takehiro Takahashi of IBM ISS X-Force for reporting the Uninitialized Memory Corruption Vulnerability (CVE-2010-3326)


Peter Vreugdenhil, working with TippingPoint's Zero Day Initiative, for reporting the Uninitialized Memory Corruption Vulnerability (CVE-2010-3328)


Damián Frizza of Core Security Technologies for reporting the Uninitialized Memory Corruption Vulnerability (CVE-2010-3329)


Aldwin Saugere and Radoslav Vasilev of Cigital for reporting the Cross-Domain Information Disclosure Vulnerability (CVE-2010-3330)


Rodrigo Rubira Branco of Check Point IPS Research Center for reporting the Uninitialized Memory Corruption Vulnerability (CVE-2010-3331)
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Microsoft Active Protections Program (MAPP)

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

Support


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


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

Disclaimer

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

Revisions


V1.0 (October 12, 2010): Bulletin published.

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