Microsoft Security Advisory (2755801)

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 where the user is using Internet Explorer 10 for the desktop, an attacker could host a website that contains a webpage that is used to exploit any of these vulnerabilities. In addition, compromised websites and websites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit any of these vulnerabilities. In all cases, however, an attacker would have no way to force users to visit these websites. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes users to the attacker's website.
• Internet Explorer 10 in the Windows 8-style UI will only play Flash content from sites listed on the Compatibility View (CV) list. This restriction requires an attacker to first compromise a website already listed in the CV list. An attacker could then host specially crafted Flash content designed to exploit any of these vulnerabilities through Internet Explorer and then convince a user to view the website. An attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by clicking a link in an email message or in an Instant Messenger message that takes users to the attacker's website, or by opening an attachment sent through email.
• By default, all supported versions of Microsoft Outlook and Windows Live Mail open HTML email messages in the Restricted sites zone. The Restricted sites zone, which disables script and ActiveX controls, helps reduce the risk of an attacker being able to use any of these vulnerabilities to execute malicious code. If a user clicks a link in an email message, the user could still be vulnerable to exploitation of any of these vulnerabilities through the web-based attack scenario.
• By default, Internet Explorer on Windows Server 2012 runs in a restricted mode that is known as Enhanced Security Configuration. This mode can help reduce the likelihood of exploitation by these vulnerabilities in Adobe Flash Player in Internet Explorer 10.

Workaround refers to a setting or configuration change that would help block known attack vectors before you apply the update.

• Prevent Adobe Flash Player from running

  You can disable attempts to instantiate Adobe Flash Player in Internet Explorer and other applications that honor the kill bit feature, such as Office 2007 and Office 2010, 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.

  To set the kill bit for the control in the registry, perform the following steps:

  1. Paste the following into a text file and save it with the .reg file extension.

     Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D27CDB6E-AE6D-11CF-96B8-444553540000}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\ActiveX Compatibility\{D27CDB6E-AE6D-11CF-96B8-444553540000}]
"Compatibility Flags"=dword:00000400


  2. Double-click the .reg file to apply it to an individual system.
     
     You can also apply it across domains by using Group Policy. For more information about Group Policy, see the TechNet article, Group Policy collection.

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

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

  How to undo the workaround. Delete the registry keys that were added in implementing this workaround.

   

• Prevent Adobe Flash Player from running on Internet Explorer 10 through Group Policy on Windows 8 and Windows Server 2012

  Note The Group Policy MMC snap-in can be used to set policy for a machine, for an organizational unit, or for an entire domain. For more information about Group Policy, visit the following Microsoft Web sites:

  Group Policy Overview

  What is Group Policy Object Editor?

  Core Group Policy tools and settings

  To disable Adobe Flash Player in Internet Explorer 10 through Group Policy on Windows 8 and Windows Server 2012, perform the following steps:

  Note This workaround does not prevent Flash from being invoked from other applications, such as Microsoft Office 2007 or Microsoft Office 2010.

  1. Open the Group Policy Management Console and configure the console to work with the appropriate Group Policy object, such as local machine, OU, or domain GPO.
  2. Navigate to the following node:
     
     Administrative Templates - Windows Components - Internet Explorer - Security Features - Add-on Management
  3. Double-click Turn off Adobe Flash in Internet Explorer and prevent applications from using Internet Explorer technology to instantiate Flash objects.
  4. Change the setting to Enabled.
  5. Click Apply and then click OK to return to the Group Policy Management Console.
  6. Refresh Group Policy on all systems or wait for the next scheduled Group Policy refresh interval for the settings to take effect.

   

• Prevent Adobe Flash Player from running in Office 2010 on Windows 8 and Windows Server 2012

  Note This workaround does not prevent Adobe Flash Player from running in Internet Explorer.

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

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

  To disable Adobe Flash Player in Office 2010 only, set the kill bit for the ActiveX control for Adobe Flash Player in the registry using the following steps:

  1. Create a text file named Disable_Flash.reg with the following contents:

     Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Common\COM\Compatibility\{D27CDB6E-AE6D-11CF-96B8-444553540000}]
"Compatibility Flags"=dword:00000400


  2. Double-click the .reg file to apply it to an individual system.
     Note You must restart Internet Explorer for your changes to take effect.

     You can also apply it across domains by using Group Policy. For more information about Group Policy, see the TechNet article, Group Policy collection.

   

• Prevent ActiveX controls from running in Office 2007 and Office 2010

  To disable all ActiveX controls in Microsoft Office 2007 and Microsoft Office 2010, including Adobe Flash Player in Internet Explorer 10, perform the following steps:

  1. Click File, click Options, click Trust Center, and then click Trust Center Settings.
  2. Click ActiveX Settings in the left-hand pane, and then select Disable all controls without notifications.
  3. Click OK to save your settings.

  Impact of workaround. Office documents that use embedded ActiveX controls may not display as intended.

  How to undo the workaround.

  To re-enable ActiveX controls in Microsoft Office 2007 and Microsoft Office 2010, perform the following steps:

  1. Click File, click Options, click Trust Center, and then click Trust Center Settings.
  2. Click ActiveX Settings in the left-hand pane, and then deselect Disable all controls without notifications.
  3. Click OK to save your settings.

   

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

  You can help protect against exploitation of these vulnerabilities by changing your settings for the Internet security zone to block ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

  To raise the browsing security level in Internet Explorer, perform the following 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 Internet.
  3. Under Security level for this zone, move the slider to High. This sets the security level for all websites you visit to High.
  4. Click Local intranet.
  5. Under Security level for this zone, move the slider to High. This sets the security level for all websites you visit to High.
  6. Click OK to accept the changes and return to Internet Explorer.

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

  Impact of workaround. There are side effects to blocking ActiveX Controls and Active Scripting. Many websites that are on the Internet or on an intranet use ActiveX or Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such sites, use the steps outlined in "Add sites that you trust to the Internet Explorer Trusted sites zone".

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

  After you set Internet Explorer to block ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to the Internet Explorer Trusted sites zone. This will allow you to continue to use trusted websites exactly as you do today, while helping to protect yourself from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

  To do this, perform the following 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 website 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 these vulnerabilities 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, perform the following 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 websites to work incorrectly. If you have difficulty using a website 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 websites 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 websites 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, perform the following 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 website 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.

   

What is the scope of the advisory? 
The purpose of this advisory is to announce the availability of an update for Adobe Flash Player in Internet Explorer 10 on Windows 8, Windows Server 2012, and Windows RT, and for Adobe Flash Player in Internet Explorer 11 on Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2.

How could an attacker exploit these vulnerabilities? 
In a web-based attack scenario where the user is using Internet Explorer 10 for the desktop, an attacker could host a specially crafted website that is designed to exploit any of these vulnerabilities through Internet Explorer and then convince a user to view the website. An attacker could also embed an ActiveX control marked "safe for initialization" in an application or Microsoft Office document that hosts the IE rendering engine. The attacker could also take advantage of compromised websites and websites that accept or host user-provided content or advertisements. These websites could contain specially crafted content that could exploit any of these vulnerabilities. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by clicking a link in an email message or in an Instant Messenger message that takes users to the attacker's website, or by opening an attachment sent through email.

In a web-based attack scenario where the user is using Internet Explorer 10 in the Windows 8-style UI, an attacker would first need to compromise a website already listed in the Compatibility View (CV) list. An attacker could then host a website that contains specially crafted Flash content designed to exploit any of these vulnerabilities through Internet Explorer and then convince a user to view the website. An attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by clicking a link in an email message or in an Instant Messenger message that takes users to the attacker's website, or by opening an attachment sent through email. For more information about Internet Explorer 10 and the CV List, please see the MSDN Article, Developer Guidance for websites with content for Adobe Flash Player in Windows 8.

If I don't use Internet Explorer, do I still need to apply the update? 
Yes, other applications, such as Microsoft Office 2007 and Microsoft Office 2010, can invoke Adobe Flash Player in Internet Explorer. Microsoft recommends that customers apply the update immediately.

What does the update do? 
The update addresses the vulnerabilities by updating the Adobe Flash libraries contained within Internet Explorer 10. The update is cumulative; customers need only install the current update.