Microsoft Security Bulletin MS15-054 - Important

Vulnerability in Microsoft Management Console File Format Could Allow Denial of Service (3051768)

Published: May 12, 2015

Version: 1.0

Executive Summary

This security update resolves a vulnerability in Microsoft Windows. The vulnerability could allow denial of service if a remote, unauthenticated attacker convinces a user to open a share containing a specially crafted .msc file. However, an attacker would have no way of forcing a user to visit the share or view the file.

This security update is rated Important for all supported editions of Microsoft Windows Vista, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows 8, Windows Server 2012, Windows RT, Windows 8.1, Windows Server 2012 R2, and Windows RT 8.1. For more information, see the Affected Software section.

The security update addresses the vulnerability by correcting how Windows validates the destination buffers in certain scenarios. For more information about the vulnerability, see the Vulnerability Information section.

For more information about this update, see Microsoft Knowledge Base Article 3051768.

Affected Software

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.

Note The update is available for Windows Technical Preview and Windows Server Technical Preview. Customers running these operating systems are encouraged to apply the update, which is available via Windows Update.

^[1]This update is available via Windows Update only.

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 May bulletin summary.

Vulnerability Information

Microsoft Management Console File Format Denial of Service Vulnerability - CVE-2015-1681

A denial of service vulnerability exists when Windows attempts to access a specially crafted .msc file to retrieve the icon information, and then fails to properly validate a destination buffer, resulting in a denial of service. An unauthenticated attacker could exploit this vulnerability by convincing a user to open a share containing a specially crafted .msc file. However, the attacker has no means to force a user to visit the share or view the file.

Servers and workstations are most at risk from this vulnerability. The update addresses the vulnerability by correcting how Windows validates the destination buffers in certain scenarios.

Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workaround

The following workaround may be helpful in your situation:

• Turn off metafile processing by modifying 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.

  1. Click Start, click Run, type Regedit in the Open box, and then click OK.

  2. Locate and then click the following registry subkey:

         HKEY_CLASSES_ROOT\lnkfile\shellex\mscfile
     

  3. Click the File menu and then click Export.

  4. In the Export Registry File dialog box, type MSC_Icon_Backup.reg and then click Save.

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

  5. In the right pane of the Registry Editor, select the value (Default). Press Enter to edit the value of the key. Delete the value, so that the value is blank, and then press Enter.

  6. Log all users off and on again, or then restart the computer.

  Impact of workaround. Disabling icons from displaying for the Microsoft Management Console Snap-in Control (.msc) files prevents the issue from being exploited on affected systems. When this workaround is implemented, the system may display some icons as a "white" default objects.

  How to undo the workaround.

  1. Click Start, click Run, type Regedit in the Open box, and then click OK.
  2. Click the File menu and then click Import.
  3. In the Import Registry File dialog box, select MSC_Icon_Backup.reg, and then click Open.
  4. Exit the Registry Editor.
  5. Restart the computer.

Security Update Deployment

For Security Update Deployment information, see the Microsoft Knowledge Base article referenced 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 12, 2015): Bulletin published.

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