Microsoft Security Bulletin MS15-008 - Important

Vulnerability in Windows Kernel-Mode Driver Could Allow Elevation of Privilege (3019215)

Published: January 13, 2015

Version: 1.0

This security update resolves one privately reported vulnerability in Microsoft Windows. The vulnerability could allow elevation of privilege if an attacker runs a specially crafted application on an affected system. An attacker must have valid logon credentials and be able to log on locally to exploit the vulnerability.

This security update is rated Important for all supported editions of Windows Server 2003, Windows Vista, Windows Server 2008 (excluding Itanium editions), Windows 7, Windows Server 2008 R2 (excluding Itanium editions), 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 impersonation levels are validated and enforced. For more information about the vulnerability, see the Vulnerability Information section.

For more information about this update, see Microsoft Knowledge Base Article 3019215.

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.

Operating System

Maximum Security Impact

Aggregate Severity Rating

Updates Replaced

Windows Server 2003

Windows Server 2003 Service Pack 2
(3019215)

Elevation of Privilege

Important

946026 in MS08-007

Windows Server 2003 x64 Edition Service Pack 2
(3019215)

Elevation of Privilege

Important

946026 in MS08-007

Windows Server 2003 with SP2 for Itanium-based Systems
(3019215)

Elevation of Privilege

Important

946026 in MS08-007

Windows Vista

Windows Vista Service Pack 2
(3019215)

Elevation of Privilege

Important

None

Windows Vista x64 Edition Service Pack 2
(3019215)

Elevation of Privilege

Important

None

Windows Server 2008

Windows Server 2008 for 32-bit Systems Service Pack 2 [1]
(3019215)

Elevation of Privilege

Important

None

Windows Server 2008 for x64-based Systems Service Pack 2 [1]
(3019215)

Elevation of Privilege

Important

None

Windows 7

Windows 7 for 32-bit Systems Service Pack 1
(3019215)

Elevation of Privilege

Important

None

Windows 7 for x64-based Systems Service Pack 1
(3019215)

Elevation of Privilege

Important

None

Windows Server 2008 R2

Windows Server 2008 R2 for x64-based Systems Service Pack 1 [1]
(3019215)

Elevation of Privilege

Important

None

Windows 8 and Windows 8.1

Windows 8 for 32-bit Systems
(3019215)

Elevation of Privilege

Important

None

Windows 8 for x64-based Systems
(3019215)

Elevation of Privilege

Important

None

Windows 8.1 for 32-bit Systems
(3019215)

Elevation of Privilege

Important

None

Windows 8.1 for x64-based Systems
(3019215)

Elevation of Privilege

Important

None

Windows Server 2012 and Windows Server 2012 R2

Windows Server 2012 [1]
(3019215)

Elevation of Privilege

Important

None

Windows Server 2012 R2 [1]
(3019215)

Elevation of Privilege

Important

None

Windows RT and Windows RT 8.1

Windows RT[2]
(3019215)

Elevation of Privilege

Important

None

Windows RT 8.1[2]
(3019215)

Elevation of Privilege

Important

None

[1]Systems running Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, or Windows Server 2012 R2 are affected only if the Desktop Experience feature is installed. These systems will not be offered the update if the Desktop Experience feature is not installed.

[2]This update is available via Windows Update only.

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 January bulletin summary.

Vulnerability Severity Rating and Maximum Security Impact by Affected Software

Affected Software

WebDAV Elevation of Privilege Vulnerability - CVE-2015-0011

Aggregate Severity Rating

Windows Server 2003

Windows Server 2003 Service Pack 2
(3019215)

Important 
Elevation of Privilege

Important 

Windows Server 2003 x64 Edition Service Pack 2
(3019215)

Important 
Elevation of Privilege

Important

Windows Server 2003 with SP2 for Itanium-based Systems
(3019215)

Important 
Elevation of Privilege

Important

Windows Vista

Windows Vista Service Pack 2
(3019215)

Important 
Elevation of Privilege

Important

Windows Vista x64 Edition Service Pack 2
(3019215)

Important 
Elevation of Privilege

Important

Windows Server 2008

Windows Server 2008 for 32-bit Systems Service Pack 2
(3019215)

Important 
Elevation of Privilege

Important

Windows Server 2008 for x64-based Systems Service Pack 2
(3019215)

Important 
Elevation of Privilege

Important

Windows 7

Windows 7 for 32-bit Systems Service Pack 1
(3019215)

Important 
Elevation of Privilege

Important

Windows 7 for x64-based Systems Service Pack 1
(3019215)

Important 
Elevation of Privilege

Important

Windows Server 2008 R2

Windows Server 2008 R2 for x64-based Systems Service Pack 1
(3019215)

Important 
Elevation of Privilege

Important

Windows 8 and Windows 8.1

Windows 8 for 32-bit Systems
(3019215)

Important 
Elevation of Privilege

Important

Windows 8 for x64-based Systems
(3019215)

Important 
Elevation of Privilege

Important

Windows 8.1 for 32-bit Systems
(3019215)

Important 
Elevation of Privilege

Important

Windows 8.1 for x64-based Systems
(3019215)

Important 
Elevation of Privilege

Important

Windows Server 2012 and Windows Server 2012 R2

Windows Server 2012
(3019215)

Important 
Elevation of Privilege

Important

Windows Server 2012 R2
(3019215)

Important 
Elevation of Privilege

Important

Windows RT and Windows RT 8.1

Windows RT[1]
(3019215)

Important 
Elevation of Privilege

Important

Windows RT 8.1[1]
(3019215)

Important 
Elevation of Privilege

Important

WebDAV Elevation of Privilege Vulnerability - CVE-2015-0011

An elevation of privilege vulnerability exists in the WebDAV kernel-mode driver (mrxdav.sys) when it fails to properly validate and enforce impersonation levels. An attacker who successfully exploited this vulnerability could bypass impersonation-level security and gain elevated privileges on a targeted system, which could allow them to intercept WebDAV requests for files from any server (including corporate SharePoint sites) and redirect those file requests to return any, potentially malicious, files of the attacker’s choosing.

To exploit this vulnerability, an attacker would first have to log on to the system and then run a specially crafted application. User interaction is required to exploit this vulnerability. The update addresses the vulnerability by correcting how the Windows kernel-mode driver validates impersonation levels.

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

The following mitigating factors may be helpful in your situation:

  • An attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.

Workarounds

The following workarounds may be helpful in your situation:

  • Disable WebDAV driver

     

    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.

     

    Interactive Method:

    1. Open Registry Editor.
    2. Locate and then click the following registry sub key:  
      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MRxDAV
      
    3. Click the File menu and then select Export.
    4. In the Export Registry File window type “MRxDAV_configuration_backup.reg” and then click Save.
    5. In Registry Editor, double-click the DWORD value named Start, change the Value data field to 4, and then click OK.
    6. Exit Registry Editor and then restart the system.

     

    Using Managed Deployment Script:

    1. Use the following managed deployment script command to make a backup copy of the WebDAV registry keys:
      regedit /e MRxDAV_configuration_backup.reg HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MRxDAV
      
    2. Save the following text to a file with a .REG extension (e.g., “Disable_MRxDAV.reg”):
      Windows Registry Editor Version 5.00
      
      HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MRxDAV]
      Start"=dword:00000004
      
    3. Use the following command on the target system to run the registry script created in the previous step:
      Regedit /s Disable_MRxDAV.reg
      
    4. Restart the system.

     

    Impact of workaround. This workaround prevents access to WebDAV shares (such as SharePoint sites) by applications that rely on Windows’ built-in support for WebDAV. Applications that provide their own WebDAV support (such as some versions of Microsoft Office applications) will be unaffected.

     

    How to undo the workaround. 

    Interactive Method:

    1. Open Registry Editor.
    2. Click the File menu and then select Import.
    3. In the Import Registry File window select “MRxDAV_configuration_backup.reg” and click Open.
    4. Restart the system.

     

    Using Managed Deployment Script:

    Run the following command at an elevated command prompt to restore the registry to its original state, then restart the system:

    Regedit /s MRxDAV_configuration_backup.reg
    

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

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

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.

  • V1.0 (January 13, 2015): Bulletin published.

Page generated 2015-02-24 11:45Z-08:00.
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