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Credit:
The information has been provided by Microsoft Product Security.
The original article can be found at: http://www.microsoft.com/technet/security/bulletin/ms06-067.mspx
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Affected Software:
* Microsoft Windows 2000 Service Pack 4
* Microsoft Windows XP Service Pack 2
* Microsoft Windows XP Professional x64 Edition
* Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1
* Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based Systems
* Microsoft Windows Server 2003 x64 Edition
Non-Affected Software:
* Windows Vista
Affected Components:
Microsoft Internet Explorer 5.01 Service Pack 4 on Windows 2000 Service Pack 4 - Download the update
Microsoft Internet Explorer 6 Service Pack 1 on Windows 2000 Service Pack 4 - Download the update
Microsoft Internet Explorer 6 for Windows XP Service Pack 2 - Download the update
Microsoft Internet Explorer 6 for Windows XP Professional x64 Edition - Download the update
Microsoft Internet Explorer 6 for Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1 - Download the update
Microsoft Internet Explorer 6 for Windows Server 2003 for Itanium-based Systems and Windows Server 2003 with SP1 for Itanium-based Systems - Download the update
Microsoft Internet Explorer 6 for Windows Server 2003 x64 Edition - Download the update
Non-Affected Components:
* Windows Internet Explorer 7 for Windows XP Service Pack 2
* Windows Internet Explorer 7 for Windows XP Professional x64 Edition
* Windows Internet Explorer 7 for Windows Server 2003 Service Pack 1
* Windows Internet Explorer 7 for Windows Server 2003 with SP1 for Itanium-based Systems
* Windows Internet Explorer 7 for Windows Server 2003 x64 Edition
* Windows Internet Explorer 7 in Windows Vista
DirectAnimation ActiveX Controls Memory Corruption Vulnerabilities - CVE-2006-4446 and CVE-2006-4777:
Remote code execution vulnerabilities exist in DirectAnimation ActiveX controls that could be exploited if the ActiveX controls are passed unexpected data. An attacker could exploit these vulnerabilities by constructing a specially crafted Web page that could potentially allow remote code execution if a user visited the specially crafted Web page. An attacker who successfully exploited these vulnerabilities could take complete control of an affected system.
Mitigating Factors for DirectAnimation ActiveX Controls Memory Corruption Vulnerabilities - CVE-2006-4446 and CVE-2006-4777:
* In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit these vulnerabilities. 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 these vulnerabilities. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to persuade users to visit the Web site, typically by getting them to click a link in an e-mail message or instant messenger message that takes users to the attacker's Web site.
* An attacker who successfully exploited these vulnerabilities could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
* The Restricted sites zone helps reduce attacks that could try to exploit these vulnerabilities by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail. However, if a user clicks on a link within an e-mail they could still be vulnerable to this issue through the Web-based attack scenario.
* By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.
* By default, Internet Explorer on Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. This mode sets the security level for the Internet zone to High. This is a mitigating factor for Web sites that have not been added to Internet Explorer Trusted sites zone. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration
Workarounds for DirectAnimation ActiveX Controls Memory Corruption Vulnerability - CVE-2006-4446 and CVE-2006-4777:
Microsoft has tested the following workarounds. Although these workarounds will not correct the underlying vulnerability, they help block known attack vectors. When a workaround reduces functionality, it is identified in the following section.
* Prevent the Microsoft DirectAnimation Path ActiveX control from running in Internet Explorer
You can help prevent attempts to instantiate this ActiveX control in Internet Explorer by setting the kill bit for the control in the registry.
Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.
For detailed steps that you can use to prevent a control from running in Internet Explorer, see Microsoft Knowledge Base Article 240797. Follow these steps in this article to create a Compatibility Flags value in the registry to prevent a COM object from being instantiated in Internet Explorer.
To set the kill bit for a CLSID with a value of {D7A7D7C3-D47F-11D0-89D3-00A0C90833E6}, paste the following text in a text editor such as Notepad. Then, save the file by using the .reg file name extension.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D7A7D7C3-D47F-11D0-89D3-00A0C90833E6}]
"Compatibility Flags"=dword:00000400
You can apply this .reg file to individual systems by double-clicking it. You can also apply it across domains by using Group Policy. For more information about Group Policy, visit the following Microsoft Web sites:
Group Policy collection
What is Group Policy Object Editor?
Core Group Policy tools and settings
Note You must restart Internet Explorer for your changes to take effect.
Impact of Workaround: Web sites that use the DirectAnimation Path ActiveX Controls may no longer display or function correctly.
This workaround can also be used for all other CLSIDs for which kill bits are being set in this security update.
* Configure Internet Explorer to prompt before running ActiveX Controls or disable ActiveX Controls in the Internet and Local intranet security zone
You can help protect against these vulnerabilities by changing your Internet Explorer settings to prompt before running ActiveX controls. To do this, follow these steps:
1. In Internet Explorer, click Internet Options on the Tools menu.
2. Click the Security tab.
3. Click Internet, and then click Custom Level.
4. Under Settings, in the ActiveX controls and plug-ins section, under Run ActiveX controls and plug-ins, click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the ActiveX controls and plug-ins section, under Run ActiveX controls and plug-ins, click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.
Impact of Workaround: There are side effects to prompting before running ActiveX controls. Many Web sites that are on the Internet or on an intranet use ActiveX to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX controls is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX controls. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to 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 computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.
* Set Internet and Local intranet security zone settings to High to prompt before running ActiveX Controls and Active Scripting in these zones
You can help protect against these vulnerabilities by changing your settings for the Internet security zone to prompt before running ActiveX controls. You can do this by setting your browser security to High.
To raise the browsing security level in Microsoft Internet Explorer, follow these steps:
1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.
Note If no slider is visible, click Default Level, and then move the slider to High.
Note Setting the level to High may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.
Impact of Workaround: There are side effects to prompting before running ActiveX controls. Many Web sites that are on the Internet or on an intranet use ActiveX to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX controls is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX controls. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to 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 computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.
FAQ for DirectAnimation ActiveX Controls Memory Corruption Vulnerabilities - CVE-2006-4446 and CVE-2006-4777:
What is the scope of the vulnerability?
These are remote code execution vulnerabilities. An attacker who successfully exploited these vulnerabilities could remotely take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.
What causes the vulnerability?
Remote code execution vulnerabilities exist in DirectAnimation ActiveX controls that could be exploited if the ActiveX controls are passed unexpected data. This could cause Internet Explorer to fail in a way that could allow code execution.
What is DirectAnimation?
DirectAnimation as a whole is a deprecated suite of development functionality. Microsoft recommends using more recent functions in Microsoft DirectX when developing Web applications and other software that needs advanced animation. After this security update is installed, Web applications and software that use DirectAnimation will not function as expected. One way of accessing the functionality that was exposed in the DirectAnimation suite was by using HTML+TIME 1.0.
What is HTML+TIME?
HTML+TIME (Timed Interactive Multimedia Extensions) adds timing and media synchronization support to HTML pages. HTML+TIME 1.0, which is a wrapper for DirectAnimation, is deprecated functionality and has been replaced by HTML+TIME 2.0. Customers who use HTML+TIME 1.0 are encouraged to use the Microsoft implementation of HTML+TIME 2.0 instead. After this security update is installed, Web applications and software that use HTML+TIME 1.0 will not function as expected.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited these vulnerabilities could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web site that is designed to exploit these vulnerabilities through Internet Explorer and then persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain specially crafted content that could exploit these vulnerabilities. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to persuade users to visit the Web site, typically by getting them to click a link in an e-mail message or in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.
What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and visits a Web site for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from these vulnerabilities.
I am running Internet Explorer on Windows Server 2003. Does this mitigate these vulnerabilities?
Yes. By default, Internet Explorer on Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. This mode sets the security level for the Internet zone to High. This is a mitigating factor for Web sites that have not been added to Internet Explorer Trusted sites zone.
What is the Internet Explorer Enhanced Security Configuration?
Internet Explorer Enhanced Security Configuration is a group of preconfigured Internet Explorer settings that reduce the likelihood of a user or of an administrator downloading and running specially crafted Web content on a server. Internet Explorer Enhanced Security Configuration reduces this risk by modifying many security-related settings. This includes the settings on the Security tab and the Advanced tab in the Internet Options dialog box. Some of the important modifications include the following:
* Security level for the Internet zone is set to High. This setting disables scripts, ActiveX controls, Microsoft Java Virtual Machine (MSJVM), and file downloads.
* Automatic detection of intranet sites is disabled. This setting assigns all intranet Web sites and all Universal Naming Convention (UNC) paths that are not explicitly listed in the Local intranet zone to the Internet zone.
* Install On Demand and non-Microsoft browser extensions are disabled. This setting prevents Web pages from automatically installing components and prevents non-Microsoft extensions from running.
* Multimedia content is disabled. This setting prevents music, animations, and video clips from running.
For more information regarding Internet Explorer Enhanced Security Configuration, see the guide, Managing Internet Explorer Enhanced Security Configuration, at the following Web site.
What does the update do?
The update removes support for the DirectAnimation Path ActiveX control in Internet Explorer by setting the kill bit for control. In addition, as a defense in depth measure, this update sets kill bits for DirectAnimation as a whole as it is a deprecated suite of development functionality. Microsoft recommends using Microsoft DirectX and HTML+TIME 2.0 when developing Web applications and other software.
The Class Identifiers and corresponding files where the DirectAnimation functionality is contained are as follows.
Class Identifier - File
{D17506C3-6B26-11D0-8914-00C04FC2A0CA} - Danim.dll
{C46C1BCE-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BDE-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BC1-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BE2-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BC6-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BF0-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BEC-3C52-11D0-9200-848C1D000000} - Danim.dll
{50B4791F-4731-11D0-8912-00C04FC2A0CA} - Danim.dll
{25B0F91C-D23D-11D0-9B85-00C04FC2F51D} - Danim.dll
{C46C1BE0-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BD4-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BEE-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BF2-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BD2-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BE6-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BD6-3C52-11D0-9200-848C1D000000} - Danim.dll
{9CDE7341-3C20-11D0-A330-00AA00B92C03} - Danim.dll
{C46C1BF4-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BD0-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BC8-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BD8-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BE4-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BC4-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BCC-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BDC-3C52-11D0-9200-848C1D000000} - Danim.dll
{AF868304-AB0B-11D0-876A-00C04FC29D46} - Danim.dll
{C46C1BCA-3C52-11D0-9200-848C1D000000} - Danim.dll
{C46C1BDA-3C52-11D0-9200-848C1D000000} - Danim.dll
{283807B5-2C60-11D0-A31D-00AA00B92C03} - Danim.dll
{B6FFC24C-7E13-11D0-9B47-00C04FC2F51D} - Danim.dll
{69AD90EF-1C20-11d1-8801-00C04FC29D46} - Danim.dll
{D7A7D7C3-D47F-11D0-89D3-00A0C90833E6} - DaxCtrle.ocx
{4F241DB1-EE9F-11D0-9824-006097C99E51} - DaxCtrle.ocx
{B0A6BAE2-AAF0-11D0-A152-00A0C908DB96} - DaxCtrle.ocx
{FD179533-D86E-11D0-89D6-00A0C90833E6} - DaxCtrle.ocx
{369303C2-D7AC-11D0-89D5-00A0C90833E6} - DaxCtrle.ocx
{BB339A46-7C49-11d2-9BF3-00C04FA34789} - Lmrt.dll
{B1549E58-3894-11D2-BB7F-00A0C999C4C1} - Lmrt.dll
When this security bulletin was issued, had these vulnerabilities been publicly disclosed?
Yes. These vulnerabilities have been publicly disclosed. They have been assigned Common Vulnerability and Exposure numbers CVE-2006-4446 and CVE-2006-4777. This security bulletin addresses the publicly disclosed vulnerabilities as well as additional issues discovered through internal investigations.
When this security bulletin was issued, had Microsoft received any reports that these vulnerabilities were being exploited?
Yes. When the security bulletin was released, Microsoft had received information that these vulnerabilities were being exploited.
Does applying this security update help protect customers from the code that has been published publicly that attempts to exploit these vulnerabilities?
Yes. This security update addresses the vulnerabilities that are currently being exploited. The vulnerabilities that have been addressed have been assigned the Common Vulnerability and Exposure number CVE-2006-4446 and CVE-2006-4777.
HTML Rendering Memory Corruption Vulnerability - CVE-2006-4687:
A remote code execution vulnerability exists in the way Internet Explorer interprets HTML with certain layout combinations. An attacker could exploit the vulnerability by constructing a specially crafted Web page that could potentially allow remote code execution if a user viewed the Web page. An attacker who successfully exploited this vulnerability could take complete control of an affected system.
Mitigating Factors for HTML Rendering Memory Corruption Vulnerability - CVE-2006-4687:
* In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to persuade users to visit the Web site, typically by getting them to click a link in an e-mail message or instant messenger message that takes users to the attacker's Web site.
* An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
* The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, the user could still be vulnerable to this issue through the Web-based attack scenario.
By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML e-mail messages in the Restricted sites zone. Additionally Outlook 2000 opens HTML e-mail messages in the Restricted sites zone if the Outlook E-mail Security Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the Restricted sites zone if Microsoft Security Bulletin MS04-018 has been installed.
Note It cannot be ruled out that this vulnerability could be used in an exploit without Active Scripting. However, using Active Scripting significantly increases the chances of a successful exploit. As a result, this vulnerability has been given a severity rating of Critical on Windows Server 2003.
* By default, Internet Explorer on Windows Server 2003 runs in a restricted mode that is known as Enhanced Security Configuration. This mode mitigates this vulnerability in the e-mail vector because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.
Workarounds for HTML Rendering Memory Corruption Vulnerability - CVE-2006-4687:
Microsoft has tested the following workarounds. Although these workarounds will not correct the underlying vulnerability, they help block known attack vectors. When a workaround reduces functionality, it is identified in the following section.
Note It cannot be ruled out that this vulnerability could be used in an exploit without Active Scripting. However, using Active Scripting significantly increases the chances of a successful exploit. As a result, this vulnerability has been given a severity rating of Critical on Windows Server 2003.
* Configure Internet Explorer to prompt before running Active Scripting or to disable Active Scripting in the Internet and Local intranet security zone
You can help protect against this vulnerability by changing your settings to prompt before running Active Scripting or to disable Active Scripting in the Internet and Local intranet security zone. To do this, follow these steps:
1. In Internet Explorer, click Internet Options on the Tools menu.
2. Click the Security tab.
3. Click Internet, and then click Custom Level.
4. Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting, click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.
Note Disabling Active Scripting in the Internet and Local intranet security zones may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly.
Impact of Workaround: There are side effects to prompting before running Active Scripting. Many Web sites that are on the Internet or on an intranet use Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use Active Scripting to provide menus, ordering forms, or even account statements. Prompting before running Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to 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 computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.
* Set Internet and Local intranet security zone settings to High to prompt before running ActiveX Controls and Active Scripting in these zones
You can help protect against this vulnerability by changing your settings for the Internet security zone to prompt before running ActiveX controls and Active Scripting. You can do this by setting your browser security to High.
To raise the browsing security level in Microsoft Internet Explorer, follow these steps:
1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.
Note If no slider is visible, click Default Level, and then move the slider to High.
Note Setting the level to High may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.
Impact of Workaround: There are side effects to prompting before running ActiveX Controls and Active Scripting. Many Web sites that are on the Internet or on an intranet use ActiveX or Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX Controls or Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to 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 computer. Two in particular that you may want to add are "*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the quotation marks). These are the sites that will host the update, and it requires an ActiveX Control to install the update.
* Read e-mail messages in plain text format if you are using Outlook 2002 or a later version, or Outlook Express 6 SP1 or a later version, to help protect yourself from the HTML e-mail attack vector.
Microsoft Outlook 2002 users who have applied Office XP Service Pack 1 or a later version and Microsoft Outlook Express 6 users who have applied Internet Explorer 6 Service Pack 1 or a later version can enable this setting and view e-mail messages that are not digitally signed or e-mail messages that are not encrypted in plain text only.
Digitally signed e-mail messages or encrypted e-mail messages are not affected by the setting and may be read in their original formats. For more information about how to enable this setting in Outlook 2002, see Microsoft Knowledge Base Article 307594.
For information about this setting in Outlook Express 6, see Microsoft Knowledge Base Article 291387.
Impact of Workaround: E-mail messages that are viewed in plain text format will not contain pictures, specialized fonts, animations, or other rich content. Additionally:
* The changes are applied to the preview pane and to open messages.
* Pictures become attachments so that they are not lost.
* Because the message is still in Rich Text or HTML format in the store, the object model (custom code solutions) may behave unexpectedly.
FAQ for HTML Rendering Memory Corruption Vulnerability - CVE-2006-4687:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.
What causes the vulnerability?
When Internet Explorer handles specially crafted HTML with certain HTML layout combinations it may corrupt system memory in such a way that an attacker could execute arbitrary code.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web site or HTML e-mail message that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site or HTML e-mail message. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. These Web sites could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to persuade users to visit the Web site, typically by getting them to click a link in an e-mail message or in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.
What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading HTML e-mail messages or that a user is logged on and visits a Web site for any malicious action to occur. Therefore, any systems where HTML e-mail messages are read or where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.
Note It cannot be ruled out that this vulnerability could be used in an exploit without Active Scripting. However, using Active Scripting significantly increases the chances of a successful exploit. As a result, this vulnerability has been given a severity rating of Critical on Windows Server 2003.
What does the update do?
The update removes the vulnerability by modifying the way that Internet Explorer decodes certain layout combinations in HTML.
When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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