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From:MICROSOFT <secure_(at)_microsoft.com>
Date:22.01.2010
Subject:Microsoft Security Bulletin MS10-002 - Critical Cumulative Security Update for Internet Explorer (978207)

Microsoft Security Bulletin MS10-002 - Critical
Cumulative Security Update for Internet Explorer (978207)
Published: January 21, 2010

Version: 1.0
General Information
Executive Summary

This security update resolves seven privately reported vulnerabilities and one publicly disclosed vulnerability in Internet Explorer. The more 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 all supported releases of Internet Explorer: Internet Explorer 5.01, Internet Explorer 6, Internet Explorer 6 Service Pack 1, Internet Explorer 7, and Internet Explorer 8 (except Internet Explorer 6 for supported editions of Windows Server 2003). For Internet Explorer 6 for supported editions of Windows Server 2003 as listed, this update is rated Moderate. 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, validates input parameters, and filters HTML attributes. For more information about the vulnerabilities, see the Frequently Asked Questions (FAQ) subsection under the next section, Vulnerability Information.

This security update also addresses the vulnerability first described in Microsoft Security Advisory 979352.

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 software listed here 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 5.01 and Internet Explorer 6 Service Pack 1

Microsoft Windows 2000 Service Pack 4


Internet Explorer 5.01 Service Pack 4


Remote Code Execution


Critical


MS09-072

Microsoft Windows 2000 Service Pack 4


Internet Explorer 6 Service Pack 1


Remote Code Execution


Critical


MS09-072
Internet Explorer 6

Windows XP Service Pack 2 and Windows XP Service Pack 3


Internet Explorer 6


Remote Code Execution


Critical


MS09-072

Windows XP Professional x64 Edition Service Pack 2


Internet Explorer 6


Remote Code Execution


Critical


MS09-072

Windows Server 2003 Service Pack 2


Internet Explorer 6


Remote Code Execution


Moderate


MS09-072

Windows Server 2003 x64 Edition Service Pack 2


Internet Explorer 6


Remote Code Execution


Moderate


MS09-072

Windows Server 2003 with SP2 for Itanium-based Systems


Internet Explorer 6


Remote Code Execution


Moderate


MS09-072
Internet Explorer 7

Windows XP Service Pack 2 and Windows XP Service Pack 3


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

Windows XP Professional x64 Edition Service Pack 2


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

Windows Server 2003 Service Pack 2


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

Windows Server 2003 x64 Edition Service Pack 2


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

Windows Server 2003 with SP2 for Itanium-based Systems


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 7


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 7


Remote Code Execution


Critical


MS09-072
Internet Explorer 8

Windows XP Service Pack 2 and Windows XP Service Pack 3


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

Windows XP Professional x64 Edition Service Pack 2


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

Windows Server 2003 Service Pack 2


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

Windows Server 2003 x64 Edition Service Pack 2


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

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


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

Windows 7 for 32-bit Systems


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

Windows 7 for x64-based Systems


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

Windows Server 2008 R2 for x64-based Systems**


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

Windows Server 2008 R2 for Itanium-based Systems


Internet Explorer 8


Remote Code Execution


Critical


MS09-072

**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 MSDN articles, Server Core and Server Core for Windows Server 2008 R2. 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?
The file information details can be found in the Microsoft Knowledge Base Article 978207.

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 December bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software XSS Filter Script Handling Vulnerability - CVE-2009-4074 URL Validation Vulnerability - CVE-2010-0027 Uninitialized Memory Corruption Vulnerability - CVE-2010-0244 Uninitialized Memory Corruption Vulnerability - CVE-2010-0245 Uninitialized Memory Corruption Vulnerability - CVE-2010-0246 Uninitialized Memory Corruption Vulnerability - CVE-2010-0247 HTML Object Memory Corruption Vulnerability - CVE-2010-0248 HTML Object Memory Corruption Vulnerability - CVE-2010-0249 Aggregate Severity Rating
Internet Explorer 5.01 and Internet Explorer 6 Service Pack 1

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


Not applicable


Not applicable


Not applicable


Not applicable


Not applicable


Critical
Remote Code Execution


Not applicable


Not applicable


Critical

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


Not applicable


Not applicable


Critical
Remote Code Execution


Not applicable


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Internet Explorer 6

Internet Explorer 6 for Windows XP Service Pack 2 and Windows XP Service Pack 3


Not applicable


Not applicable


Critical
Remote Code Execution


Not applicable


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

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


Not applicable


Not applicable


Critical
Remote Code Execution


Not applicable


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

Internet Explorer 6 for Windows Server 2003 Service Pack 2


Not applicable


Not applicable


Moderate
Remote Code Execution


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate

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


Not applicable


Not applicable


Moderate
Remote Code Execution


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate

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


Not applicable


Not applicable


Moderate
Remote Code Execution


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Internet Explorer 7

Internet Explorer 7 for Windows XP Service Pack 2 and Windows XP Service Pack 3


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Not applicable


Not applicable


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

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


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Not applicable


Not applicable


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

Internet Explorer 7 for Windows Server 2003 Service Pack 2


Not applicable


Critical
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Not applicable


Critical
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Not applicable


Critical
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Not applicable


Not applicable


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

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


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Not applicable


Not applicable


Not applicable


Critical
Remote Code Execution


Critical
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**


Not applicable


Critical
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Not applicable


Critical
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Not applicable


Critical
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Not applicable


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical
Internet Explorer 8

Internet Explorer 8 for Windows XP Service Pack 2 and Windows XP Service Pack 3


Moderate
Information Disclosure


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

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


Moderate
Information Disclosure


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

Internet Explorer 8 for Windows Server 2003 Service Pack 2


Low
Information Disclosure


Critical
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Low
Information Disclosure


Critical
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Moderate
Information Disclosure


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

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


Moderate
Information Disclosure


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical
Remote Code Execution


Not applicable


Critical
Remote Code Execution


Critical
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**


Low
Information Disclosure


Critical
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Low
Information Disclosure


Critical
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

Internet Explorer 8 in Windows 7 for 32-bit Systems


Moderate
Information Disclosure


Critical
Remote Code Execution


Critical
Remote Code Execution


Low
Denial of Service


Critical
Remote Code Execution


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

Internet Explorer 8 in Windows 7 for x64-based Systems


Moderate
Information Disclosure


Critical
Remote Code Execution


Critical
Remote Code Execution


Low
Denial of Service


Critical
Remote Code Execution


Not applicable


Critical
Remote Code Execution


Critical
Remote Code Execution


Critical

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


Low
Information Disclosure


Critical
Remote Code Execution


Moderate
Remote Code Execution


Low
Denial of Service


Moderate
Remote Code Execution


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

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


Low
Information Disclosure


Critical
Remote Code Execution


Moderate
Remote Code Execution


Low
Denial of Service


Moderate
Remote Code Execution


Not applicable


Moderate
Remote Code Execution


Moderate
Remote Code Execution


Critical

**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 MSDN articles, Server Core and Server Core for Windows Server 2008 R2. 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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XSS Filter Script Handling Vulnerability - CVE-2009-4074

An XSS filter bypass vulnerability exists in the way that Internet Explorer 8 disables an HTML attribute in otherwise appropriately filtered HTTP response data. The vulnerability could allow initially disabled scripts to run in the wrong security context, leading to information disclosure.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-4074.

Mitigating Factors for XSS Filter Script Handling Vulnerability - CVE-2009-4074

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:


Internet Explorer 5.01 Service Pack 4, Internet Explorer 6.0, Internet Explorer 6 Service Pack 1, and Internet Explorer 7 are not affected by this vulnerability.
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Workarounds for XSS Filter Script Handling Vulnerability - CVE-2009-4074

Microsoft has not identified any workarounds for this vulnerability.
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FAQ for XSS Filter Script Handling Vulnerability - CVE-2009-4074

What is the scope of the vulnerability?
This is an information disclosure vulnerability. An attacker could exploit the vulnerability either by constructing a specially crafted Web page or posting specially crafted content to a legitimate Web site. An attacker who successfully exploited this vulnerability could cause script code to run on the machine of another user in the guise of a third-party Web site. Such script code would run inside the browser when visiting the third-party Web site, and could take any action on the user's computer that the third-party Web site was permitted to take. The vulnerability could only be exploited if the user clicked on a hypertext link, either in an HTML e-mail or if the user visited an attacker's Web site or a Web site containing content that is under the attacker’s control.

What causes the vulnerability?
Internet Explorer, under certain circumstances, disables an HTML attribute in otherwise appropriately filtered response data. As a result, a specially crafted Web page could be loaded in such a way that an attacker could execute script in the context of the logged-on user in a different Internet domain.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause script code to run on the machine of another user in the guise of a third-party Web site. Such script code would run inside the browser when visiting the third-party Web site, and could take any action on the user's computer that the third-party Web site was permitted to take. The vulnerability could only be exploited if the user clicked on a hypertext link, either in an HTML e-mail or if the user visited an attacker's Web site or a Web site containing content that is under the attacker’s control.

How could an attacker exploit the vulnerability?
An attacker could post specially crafted content, designed to exploit this vulnerability, on to an affected Web site. The attacker must then convince the user to view the content on the Web site. When the user browses to the legitimate Web site, the XSS filter disables HTML attributes in the crafted content, creating a condition that could allow malicious script to run in the wrong security context, leading to information disclosure.

What systems are primarily at risk from the vulnerability?
A user must be logged on and visiting a Web site for malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations and 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 preventing the XSS filter in Internet Explorer from incorrectly disabling HTML attributes.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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URL Validation Vulnerability - CVE-2010-0027

A remote code execution vulnerability exists in the way that Internet Explorer incorrectly validates input. An attacker could exploit the vulnerability by constructing a specially crafted URL. When a user clicks the URL, 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-2010-0027.

Mitigating Factors for URL Validation Vulnerability - CVE-2010-0027

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. The Restricted sites zone helps mitigate attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, the user could still be vulnerable to 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.


Internet Explorer 5.01 Service Pack 4, Internet Explorer 6.0, and Internet Explorer 6 Service Pack 1 are not affected by this vulnerability.
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Workarounds for URL Validation Vulnerability - CVE-2010-0027

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 prompt before running 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 prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

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

1.


On the Internet Explorer Tools menu, click Internet Options.

2.


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

3.


Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

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

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

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


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 URL Validation Vulnerability - CVE-2010-0027

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 processes a specially crafted URL, code that is called to validate the URL could execute a binary from the local client system.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could gain the same user rights as the 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 convince a user to click on a specially crafted link that Internet Explorer may improperly validate, allowing code to execute on the system. In all cases, however, an attacker would have no way to force users to click on the URL. Instead, an attacker would have to convince users to click the URL, typically by sending them an e-mail message or in an Instant Messenger message. 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 correcting the behavior of Internet Explorer so that input parameters are sufficiently validated.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Uninitialized Memory Corruption Vulnerability - CVE-2010-0244

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-2010-0244.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2010-0244

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:


Data Execution Protection (DEP) helps protect against attacks that result in code execution and is enabled by default in Internet Explorer 8 on the following Windows operating systems: Windows XP Service Pack 3, Windows Vista Service Pack 1, Windows Vista Service Pack 2, and Windows 7.


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. The Restricted sites zone helps mitigate attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, the user could still be vulnerable to 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.


Internet Explorer 5.01 Service Pack 4 is not affected by this vulnerability.
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Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2010-0244

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 prompt before running 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 prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

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

1.


On the Internet Explorer Tools menu, click Internet Options.

2.


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

3.


Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

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

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

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


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.


Enable DEP for Internet Explorer 6 or Internet Explorer 7

This vulnerability is more difficult to exploit successfully if Data Execution Protection (DEP) is enabled for Internet Explorer. You can enable DEP for all versions of Internet Explorer that support DEP, using one of the following methods:


Enable DEP for Internet Explorer 7 interactively

Local Administrators can control DEP/NX by running Internet Explorer as an Administrator. To enable DEP, perform the following steps:

1.


In Internet Explorer, click Tools, click Internet Options, and then click Advanced.

2.


Click Enable memory protection to help mitigate online attacks.

3.


Click OK and then restart Internet Explorer.


Enable DEP for Internet Explorer 6 or Internet Explorer 7 using automated Microsoft Fix It

See Microsoft Knowledge Base Article 978207 to use the automated Microsoft Fix it solution to enable or disable this workaround.

Impact of workaround. Some browser extensions may not be compatible with DEP and may exit unexpectedly. If this occurs, you can disable the add-on, or revert the DEP setting using the Internet Control Panel. This is also accessible using the System Control panel.
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FAQ for Uninitialized Memory Corruption Vulnerability - CVE-2010-0244

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. 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.

Which of the workarounds should I apply to my system in order to be protected?
Based on our investigation, setting the Internet zone security setting to High will protect users from the issue described in this advisory.

How does configuring the Internet zone security setting to High protect me from this vulnerability?
Setting the Internet zone security setting to High protects against this vulnerability by disabling scripting, disabling less secure features in Internet Explorer, and blocking known techniques used to bypass Data Execution Prevention (DEP).

How does Protected Mode in Internet Explorer on Windows Vista and later Windows operating systems limit the impact of this vulnerability?
Internet Explorer in Windows Vista and later Windows operating systems runs in Protected Mode by default in the Internet security zone. (Protected Mode is off by default in the Intranet zone.) Protected Mode significantly reduces the ability of an attacker to write, alter, or destroy data on the user’s machine or to install malicious code. This is accomplished by using the integrity mechanisms of Windows Vista which restrict access to processes, files, and registry keys with higher integrity levels.

What is Address Space Layout Randomization (ASLR)?
Systems implementing Address Space Layout Randomization relocate normally-predictable function entry points pseudo-randomly in memory. Windows ASLR re-bases DLL or EXE into one of 256 random locations in memory. Therefore, attackers using hardcoded addresses are likely to "guess correctly" one in 256 times. For more information regarding ASLR, visit the TechNet magazine article, Inside the Windows Vista Kernel: Part 3.

What is Data Execution Prevention (DEP)?
Data Execution Prevention support is included in Internet Explorer, and although on by default for Internet Explorer 8, is off by default for earlier versions of Internet Explorer. DEP is designed to help foil attacks by preventing code from running in memory that is marked non-executable. For more information about DEP in Internet Explorer, please see the MSDN blog post, IE8 Security Part I: DEP/NX Memory Protection.

Can Data Execution Prevention (DEP) be bypassed in Internet Explorer 8?
There is a report of a new Data Execution Prevention (DEP) exploit. We have analyzed the proof-of-concept exploit code and have found that Windows Vista and later versions of Windows offer more effective protections in blocking the exploit due to Address Space Layout Randomization (ASLR). On Windows XP, attackers could make the bypass techniques more reliable.

What does the update do?
The update modifies 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 responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Uninitialized Memory Corruption Vulnerability - CVE-2010-0245

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-2010-0245.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2010-0245

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. The Restricted sites zone helps mitigate attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, the user could still be vulnerable to 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.


Internet Explorer 5.01 Service Pack 4, Internet Explorer 6, Internet Explorer 6 Service Pack 1, and Internet Explorer 7 are not affected by this vulnerability.
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Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2010-0245

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 prompt before running 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 prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

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

1.


On the Internet Explorer Tools menu, click Internet Options.

2.


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

3.


Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

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

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

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


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-2010-0245

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. 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 modifies 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 responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Uninitialized Memory Corruption Vulnerability - CVE-2010-0246

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-2010-0246.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2010-0246

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:


Data Execution Protection (DEP) helps protect against attacks that result in code execution and is enabled by default in Internet Explorer 8 on the following Windows operating systems: Windows XP Service Pack 3, Windows Vista Service Pack 1, Windows Vista Service Pack 2, and Windows 7.


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. The Restricted sites zone helps mitigate attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, the user could still be vulnerable to 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.


Internet Explorer 5.01 Service Pack 4, Internet Explorer 6, Internet Explorer 6 Service Pack 1, and Internet Explorer 7 are not affected by this vulnerability.
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Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2010-0246

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 prompt before running 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 prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

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

1.


On the Internet Explorer Tools menu, click Internet Options.

2.


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

3.


Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

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

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

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


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.


Enable DEP for Internet Explorer 6 or Internet Explorer 7

This vulnerability is more difficult to exploit successfully if Data Execution Protection (DEP) is enabled for Internet Explorer. You can enable DEP for all versions of Internet Explorer that support DEP, using one of the following methods:


Enable DEP for Internet Explorer 7 interactively

Local Administrators can control DEP/NX by running Internet Explorer as an Administrator. To enable DEP, perform the following steps:

1.


In Internet Explorer, click Tools, click Internet Options, and then click Advanced.

2.


Click Enable memory protection to help mitigate online attacks.

3.


Click OK and then restart Internet Explorer.


Enable DEP for Internet Explorer 6 or Internet Explorer 7 using automated Microsoft Fix It

See Microsoft Knowledge Base Article 978207 to use the automated Microsoft Fix it solution to enable or disable this workaround.

Impact of workaround. Some browser extensions may not be compatible with DEP and may exit unexpectedly. If this occurs, you can disable the add-on, or revert the DEP setting using the Internet Control Panel. This is also accessible using the System Control panel.
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FAQ for Uninitialized Memory Corruption Vulnerability - CVE-2010-0246

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. 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.

Which of the workarounds should I apply to my system in order to be protected?
Based on our investigation, setting the Internet zone security setting to High will protect users from the issue described in this advisory.

How does configuring the Internet zone security setting to High protect me from this vulnerability?
Setting the Internet zone security setting to High protects against this vulnerability by disabling scripting, disabling less secure features in Internet Explorer, and blocking known techniques used to bypass Data Execution Prevention (DEP).

How does Protected Mode in Internet Explorer on Windows Vista and later Windows operating systems limit the impact of this vulnerability?
Internet Explorer in Windows Vista and later Windows operating systems runs in Protected Mode by default in the Internet security zone. (Protected Mode is off by default in the Intranet zone.) Protected Mode significantly reduces the ability of an attacker to write, alter, or destroy data on the user’s machine or to install malicious code. This is accomplished by using the integrity mechanisms of Windows Vista which restrict access to processes, files, and registry keys with higher integrity levels.

What is Address Space Layout Randomization (ASLR)?
Systems implementing Address Space Layout Randomization relocate normally-predictable function entry points pseudo-randomly in memory. Windows ASLR re-bases DLL or EXE into one of 256 random locations in memory. Therefore, attackers using hardcoded addresses are likely to "guess correctly" one in 256 times. For more information regarding ASLR, visit the TechNet magazine article, Inside the Windows Vista Kernel: Part 3.

What is Data Execution Prevention (DEP)?
Data Execution Prevention support is included in Internet Explorer, and although on by default for Internet Explorer 8, is off by default for earlier versions of Internet Explorer. DEP is designed to help foil attacks by preventing code from running in memory that is marked non-executable. For more information about DEP in Internet Explorer, please see the MSDN blog post, IE8 Security Part I: DEP/NX Memory Protection.

Can Data Execution Prevention (DEP) be bypassed in Internet Explorer 8?
There is a report of a new Data Execution Prevention (DEP) exploit. We have analyzed the proof-of-concept exploit code and have found that Windows Vista and later versions of Windows offer more effective protections in blocking the exploit due to Address Space Layout Randomization (ASLR). On Windows XP, attackers could make the bypass techniques more reliable.

What does the update do?
The update modifies 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 responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Uninitialized Memory Corruption Vulnerability - CVE-2010-0247

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-2010-0247.

Mitigating Factors for Uninitialized Memory Corruption Vulnerability - CVE-2010-0247

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. The Restricted sites zone helps mitigate attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, the user could still be vulnerable to 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.


Internet Explorer 7 and Internet Explorer 8 are not affected by this vulnerability.
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Workarounds for Uninitialized Memory Corruption Vulnerability - CVE-2010-0247

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 prompt before running 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 prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

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

1.


On the Internet Explorer Tools menu, click Internet Options.

2.


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

3.


Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

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

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

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


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-2010-0247

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. 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 modifies 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 responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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HTML Object Memory Corruption Vulnerability - CVE-2010-0248

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-2010-0248.

Mitigating Factors for HTML Object Memory Corruption Vulnerability - CVE-2010-0248

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:


Data Execution Protection (DEP) helps protect against attacks that result in code execution and is enabled by default in Internet Explorer 8 on the following Windows operating systems: Windows XP Service Pack 3, Windows Vista Service Pack 1, Windows Vista Service Pack 2, and Windows 7.


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. The Restricted sites zone helps mitigate attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, the user could still be vulnerable to 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.


Internet Explorer 5.01 Service Pack 4 is not affected by this vulnerability.
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Workarounds for HTML Object Memory Corruption Vulnerability - CVE-2010-0248

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 prompt before running 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 prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

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

1.


On the Internet Explorer Tools menu, click Internet Options.

2.


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

3.


Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

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

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

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


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.


Enable DEP for Internet Explorer 6 or Internet Explorer 7

This vulnerability is more difficult to exploit successfully if Data Execution Protection (DEP) is enabled for Internet Explorer. You can enable DEP for all versions of Internet Explorer that support DEP, using one of the following methods:


Enable DEP for Internet Explorer 7 interactively

Local Administrators can control DEP/NX by running Internet Explorer as an Administrator. To enable DEP, perform the following steps:

1.


In Internet Explorer, click Tools, click Internet Options, and then click Advanced.

2.


Click Enable memory protection to help mitigate online attacks.

3.


Click OK and then restart Internet Explorer.


Enable DEP for Internet Explorer 6 or Internet Explorer 7 using automated Microsoft Fix It

See Microsoft Knowledge Base Article 978207 to use the automated Microsoft Fix it solution to enable or disable this workaround.

Impact of workaround. Some browser extensions may not be compatible with DEP and may exit unexpectedly. If this occurs, you can disable the add-on, or revert the DEP setting using the Internet Control Panel. This is also accessible using the System Control panel.
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FAQ for HTML Object Memory Corruption Vulnerability - CVE-2010-0248

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 incorrectly initialized memory under certain conditions, 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. 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.

Which of the workarounds should I apply to my system in order to be protected?
Based on our investigation, setting the Internet zone security setting to High will protect users from the issue described in this advisory.

How does configuring the Internet zone security setting to High protect me from this vulnerability?
Setting the Internet zone security setting to High protects against this vulnerability by disabling scripting, disabling less secure features in Internet Explorer, and blocking known techniques used to bypass Data Execution Prevention (DEP).

How does Protected Mode in Internet Explorer on Windows Vista and later Windows operating systems limit the impact of this vulnerability?
Internet Explorer in Windows Vista and later Windows operating systems runs in Protected Mode by default in the Internet security zone. (Protected Mode is off by default in the Intranet zone.) Protected Mode significantly reduces the ability of an attacker to write, alter, or destroy data on the user’s machine or to install malicious code. This is accomplished by using the integrity mechanisms of Windows Vista which restrict access to processes, files, and registry keys with higher integrity levels.

What is Address Space Layout Randomization (ASLR)?
Systems implementing Address Space Layout Randomization relocate normally-predictable function entry points pseudo-randomly in memory. Windows ASLR re-bases DLL or EXE into one of 256 random locations in memory. Therefore, attackers using hardcoded addresses are likely to "guess correctly" one in 256 times. For more information regarding ASLR, visit the TechNet magazine article, Inside the Windows Vista Kernel: Part 3.

What is Data Execution Prevention (DEP)?
Data Execution Prevention support is included in Internet Explorer, and although on by default for Internet Explorer 8, is off by default for earlier versions of Internet Explorer. DEP is designed to help foil attacks by preventing code from running in memory that is marked non-executable. For more information about DEP in Internet Explorer, please see the MSDN blog post, IE8 Security Part I: DEP/NX Memory Protection.

Can Data Execution Prevention (DEP) be bypassed in Internet Explorer 8?
There is a report of a new Data Execution Prevention (DEP) exploit. We have analyzed the proof-of-concept exploit code and have found that Windows Vista and later versions of Windows offer more effective protections in blocking the exploit due to Address Space Layout Randomization (ASLR). On Windows XP, attackers could make the bypass techniques more reliable.

What does the update do?
The update modifies 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 responsible disclosure.

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

HTML Object Memory Corruption Vulnerability - CVE-2010-0249

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-2010-0249.

Mitigating Factors for HTML Object Memory Corruption Vulnerability - CVE-2010-0249

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:


Data Execution Protection (DEP) helps protect against attacks that result in code execution and is enabled by default in Internet Explorer 8 on the following Windows operating systems: Windows XP Service Pack 3, Windows Vista Service Pack 1, Windows Vista Service Pack 2, and Windows 7.


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. The Restricted sites zone helps mitigate attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, the user could still be vulnerable to 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.


Internet Explorer 5.01 Service Pack 4 is not affected by this vulnerability.
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Workarounds for HTML Object Memory Corruption Vulnerability - CVE-2010-0249

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 prompt before running 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 prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

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

1.


On the Internet Explorer Tools menu, click Internet Options.

2.


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

3.


Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

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

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

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


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.


Enable DEP for Internet Explorer 6 or Internet Explorer 7

This vulnerability is more difficult to exploit successfully if Data Execution Protection (DEP) is enabled for Internet Explorer. You can enable DEP for all versions of Internet Explorer that support DEP, using one of the following methods:


Enable DEP for Internet Explorer 7 interactively

Local Administrators can control DEP/NX by running Internet Explorer as an Administrator. To enable DEP, perform the following steps:

1.


In Internet Explorer, click Tools, click Internet Options, and then click Advanced.

2.


Click Enable memory protection to help mitigate online attacks.

3.


Click OK and then restart Internet Explorer.


Enable DEP for Internet Explorer 6 or Internet Explorer 7 using automated Microsoft Fix It

See Microsoft Knowledge Base Article 978207 to use the automated Microsoft Fix it solution to enable or disable this workaround.

Impact of workaround. Some browser extensions may not be compatible with DEP and may exit unexpectedly. If this occurs, you can disable the add-on, or revert the DEP setting using the Internet Control Panel. This is also accessible using the System Control panel.


Enable or disable ActiveX controls in Office 2007

To reduce the possibility of this vulnerability being exploited through an Office 2007 document using an ActiveX control, follow the steps below to disable ActiveX controls within Office documents. For more information about disabling ActiveX controls in Office 2007, see the Microsoft Office Online article, Enable or disable ActiveX controls in Office documents.

Open the Trust Center in Office 2007 applications using one of the following methods. Once you have selected the ActiveX Settings, select Disable all controls without notification, and then click OK.

Note If you change an ActiveX control setting in one Office application, the settings are also changed in all the other Office programs on your computer.

Excel

Click the Microsoft Office button, select Excel Options, select TrustCenter, select Trust Center Settings, and then select ActiveX Settings.

Outlook

From the Tools menu, select TrustCenter, select Trust Center Settings, and then select ActiveX Settings.

PowerPoint

Click the Microsoft Office button, select PowerPoint Options, select Trust Center, select Trust Center Settings, and then select ActiveX Settings.

Word

Click the Microsoft Office button, select Word Options, select Trust Center, selectTrustCenter Settings, and then select ActiveX Settings.

Access

Click the Microsoft Office button, select Access Options, select Trust Center, select Trust Center Settings, and then select ActiveX Settings.

InfoPath

From the Tools menu, select Trust Center, select Trust Center Settings, and then select ActiveX Settings.

Publisher

From the Tools menu, select Trust Center, select Trust Center Settings, and then select ActiveX Settings.

Visio

From the Tools menu, select Trust Center, select Trust Center Settings, and then select ActiveX Settings.

Impact of workaround. ActiveX controls will not be instantiated in Microsoft Office applications.


Do not open unexpected files

Do not open Microsoft Office files that you receive from untrusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted file.
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FAQ for HTML Object Memory Corruption Vulnerability - CVE-2010-0249

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 incorrectly initialized memory under certain conditions, 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. 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.

Which of the workarounds should I apply to my system in order to be protected?
Based on our investigation, setting the Internet zone security setting to High will protect users from the issue described in this advisory.

How does configuring the Internet zone security setting to High protect me from this vulnerability?
Setting the Internet zone security setting to High protects against this vulnerability by disabling scripting, disabling less secure features in Internet Explorer, and blocking known techniques used to bypass Data Execution Prevention (DEP).

How does Protected Mode in Internet Explorer on Windows Vista and later Windows operating systems limit the impact of this vulnerability?
Internet Explorer in Windows Vista and later Windows operating systems runs in Protected Mode by default in the Internet security zone. (Protected Mode is off by default in the Intranet zone.) Protected Mode significantly reduces the ability of an attacker to write, alter, or destroy data on the user’s machine or to install malicious code. This is accomplished by using the integrity mechanisms of Windows Vista which restrict access to processes, files, and registry keys with higher integrity levels.

What is Address Space Layout Randomization (ASLR)?
Systems implementing Address Space Layout Randomization relocate normally-predictable function entry points pseudo-randomly in memory. Windows ASLR re-bases DLL or EXE into one of 256 random locations in memory. Therefore, attackers using hardcoded addresses are likely to "guess correctly" one in 256 times. For more information regarding ASLR, visit the TechNet magazine article, Inside the Windows Vista Kernel: Part 3.

What is Data Execution Prevention (DEP)?
Data Execution Prevention support is included in Internet Explorer, and although on by default for Internet Explorer 8, is off by default for earlier versions of Internet Explorer. DEP is designed to help foil attacks by preventing code from running in memory that is marked non-executable. For more information about DEP in Internet Explorer, please see the MSDN blog post, IE8 Security Part I: DEP/NX Memory Protection.

Can Data Execution Prevention (DEP) be bypassed in Internet Explorer 8?
There is a report of a new Data Execution Prevention (DEP) exploit. We have analyzed the proof-of-concept exploit code and have found that Windows Vista and later versions of Windows offer more effective protections in blocking the exploit due to Address Space Layout Randomization (ASLR). On Windows XP, attackers could make the bypass techniques more reliable.

What does the update do?
The update modifies the way that Internet Explorer handles objects in memory.

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-2010-0249.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
Yes. Microsoft is aware of limited attacks attempting to exploit the vulnerability.

Other Information
Acknowledgments

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


David Lindsay "thornmaker" and Eduardo A. Vela Nava "sirdarckcat" for reporting the XSS Filter Script Handling Vulnerability (CVE-2009-4074)


Lostmon Lords for reporting the URL Validation Vulnerability (CVE-2010-0027)


Brett Moore, working with TippingPoint and the Zero Day Initiative, for reporting the URL Validation Vulnerability (CVE-2010-0027)


Wushi of team509, working with TippingPoint and the Zero Day Initiative, for reporting the Uninitialized Memory Corruption Vulnerability (CVE-2010-0244)


Sam Thomas of eshu.co.uk, working with TippingPoint and the Zero Day Initiative, for reporting the Uninitialized Memory Corruption Vulnerability (CVE-2010-0245)


Sam Thomas of eshu.co.uk, working with TippingPoint and the Zero Day Initiative, for reporting the Uninitialized Memory Corruption Vulnerability (CVE-2010-0246)


Haifei Li of Fortinet’s FortiGuard Labs for reporting the Uninitialized Memory Corruption Vulnerability (CVE-2010-0247)


Peter Vreugdenhil, working with TippingPoint and the Zero Day Initiative, for reporting the HTML Object Memory Corruption Vulnerability (CVE-2010-0248)


Meron Sellem of BugSec for reporting the HTML Object Memory Corruption Vulnerability (CVE-2010-0249)

Microsoft thanks the following companies for working with us and for providing details of limited, targeted attacks against customers of Internet Explorer 6:


Google Inc. and MANDIANT


Adobe


McAfee


French government CSIRT (CERTA)
Top of sectionTop of section
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 (January 21, 2010): Bulletin published.

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