Microsoft Security Bulletin MS16-059 - Important

Security Update for Windows Media Center (3150220)

Published: May 10, 2016

Version: 1.0

Executive Summary

This security update resolves a vulnerability in Microsoft Windows. The vulnerability could allow remote code execution if Windows Media Center opens a specially crafted Media Center link (.mcl) file that references malicious code. An attacker who successfully exploited this vulnerability could gain the same user rights as the current user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

This security update is rated Important for all supported editions of Windows Media Center when installed on Windows Vista, Windows 7, or Windows 8.1. For more information, see the Affected Software section.

The security update addresses the vulnerability by correcting how Windows Media Center handles certain resources in the .mcl file. For more information about the vulnerability, see the Vulnerability Information section.

For more information about this update, see Microsoft Knowledge Base Article 3150220.

Affected Software and Vulnerability Severity Ratings

The following software versions or editions are affected. Versions or editions that are not listed are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.

The severity ratings indicated for each affected software 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 May bulletin summary.

Vulnerability Information

Windows Media Center Remote Code Execution Vulnerability - CVE-2016-0185

A vulnerability exists in Windows Media Center that could allow remote code execution if Windows Media Center opens a specially crafted Media Center link (.mcl) file that references malicious code. An attacker who successfully exploited this vulnerability could take control of an affected system. Customers whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. Workstations are primarily at risk of this vulnerability.

To exploit the vulnerability, user interaction is required. In a web-browsing scenario, a user would have to navigate to a compromised website that an attacker is using to host a malicious .mcl file. In an email attack scenario, an attacker would have to convince a user who is logged on to a vulnerable workstation to click a specially crafted link in an email. The security update addresses the vulnerability by correcting how Windows Media Center handles certain resources in the .mcl file.

The following table contains links to the standard entry for each vulnerability in the Common Vulnerabilities and Exposures list:

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

The following workarounds may be helpful in your situation:

Remove the MCL file association

• To use the interactive method:
  Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys and Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

  1. Click Start, click Run, type regedit, and then click OK.

  2. Expand HKEY_CLASSES_ROOT, click .MCL, and then click the File menu and select Export.

  3. In the Export Registry File dialog box, type MCL HKCR file association registry backup.reg and click Save.

     This will create a backup of this registry key in the My Documents folder by default.

  4. Press the Delete key to delete the registry key. When prompted to delete the registry value, click Yes.

  5. Expand HKEY_CURRENT_USER, then Software, then Microsoft, then Windows, then CurrentVersion, then Explorer, and then FileExts.

  6. Click .MCL, and then click the File menu and select Export.

  7. In the Export Registry File dialog box, type MCL HKCU file association registry backup.reg and click Save.

     This will create a backup of this registry key in the My Documents folder by default.

  8. Press the Delete key to delete the registry key. When prompted to delete the registry value, click Yes.

• To use the managed deployment script method:

  1. Make a backup copy of the registry keys from a managed deployment script using the following commands:

     Regedit.exe /e MCL_HKCR_registry_backup.reg HKEY_CLASSES_ROOT\.MCL Regedit.exe /e MCL_HKCU_registry_backup.reg HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.MCL

  2. Save the following to a file with a .reg extension (for example, Delete_MCL_file_association.reg):

         Windows Registry Editor Version 5.00  
         [-HKEY_CLASSES_ROOT\.MCL]  
         [-HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\ 
         FileExts\.MCL]
     

  3. Run the registry script that you created in Step 2 on the target machine using the following command:
     Regedit.exe /s Delete_EXTENSION_file_association.reg

     How to undo the workaround.

     1. Restore the registry key by using Regedit to restore the settings saved in the .REG file.

Security Update Deployment

For Security Update Deployment information, see the Microsoft Knowledge Base article referenced here in the Executive Summary.

Acknowledgments

Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgments for more information.

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 (May 10, 2016): Bulletin published.

Page generated 2016-05-04 11:08-07:00.