Microsoft Security Bulletin MS15-083 - Important

Vulnerability in Server Message Block Could Allow Remote Code Execution (3073921)

Published: August 11, 2015 | Updated: September 8, 2015

Version: 2.0

This security update resolves a vulnerability in Microsoft Windows. The vulnerability could allow remote code execution if an attacker sends a specially crafted string to the SMB server error logging.

This security update is rated Important for all supported editions of Windows Vista and Windows Server 2008. For more information, see the Affected Software section.

The security update addresses the vulnerability by correcting certain logging activities to preclude memory corruption. For more information about the vulnerability, see the Vulnerability Information section.

For more information about this update, see Microsoft Knowledge Base Article 3073921.

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 Vista

Windows Vista Service Pack 2
(3073921)

Remote Code Execution

Important

971468 in MS10-012

Windows Vista x64 Edition Service Pack 2
(3073921)

Remote Code Execution

Important

971468 in MS10-012

Windows Server 2008

Windows Server 2008 for 32-bit Systems Service Pack 2
(3073921)

Remote Code Execution

Important

971468 in MS10-012

Windows Server 2008 for x64-based Systems Service Pack 2
(3073921)

Remote Code Execution

Important

971468 in MS10-012

Windows Server 2008 for Itanium-based Systems Service Pack 2
(3073921)

Remote Code Execution

Important

971468 in MS10-012

Server Core installation option

Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
(3073921)

Remote Code Execution

Important

971468 in MS10-012

Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
(3073921)

Remote Code Execution

Important

971468 in MS10-012

*The Updates Replaced column shows only the latest update in any chain of superseded updates. For a comprehensive list of updates replaced, go to the Microsoft Update Catalog, search for the update KB number, and then view update details (updates replaced information is provided on the Package Details tab).

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 August bulletin summary.

Vulnerability Severity Rating and Maximum Security Impact by Affected Software

Affected Software

Server Message Block Memory Corruption Vulnerability - CVE-2015-2474

Aggregate Severity Rating

Windows Vista

Windows Vista Service Pack 2
(3073921)

Important 
Remote Code Execution

Important 

Windows Vista x64 Edition Service Pack 2
(3073921)

Important 
Remote Code Execution

Important 

Windows Server 2008

Windows Server 2008 for 32-bit Systems Service Pack 2
(3073921)

Important 
Remote Code Execution

Important 

Windows Server 2008 for x64-based Systems Service Pack 2
(3073921)

Important 
Remote Code Execution

Important 

Windows Server 2008 for Itanium-based Systems Service Pack 2
(3073921)

Important 
Remote Code Execution

Important 

Server Core installation option

Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
(3073921)

Important 
Remote Code Execution

Important 

Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
(3073921)

Important 
Remote Code Execution

Important 

Server Message Block Memory Corruption Vulnerability - CVE-2015-2474

An authenticated remote code execution vulnerability exists in Windows that is caused when Server Message Block (SMB) improperly handles certain logging activities, resulting in memory corruption. An attacker who successfully exploited this vulnerability could 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.

In an attack scenario, an attacker would possess a valid credential and send a specially crafted string to the SMB server error logging.

The update addresses the vulnerability by correcting certain logging activities to preclude memory corruption. Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was 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.

Workarounds

The following workarounds may be helpful in your situation:

  • Disable SMBv1

    Method 1 (using PowerShell):

    1. On Windows Vista and Windows Server 2008 with PowerShell 2.0 or newer, you can execute the following PowerShell command:
      Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" SMB1 -Type DWORD -Value 0 –Force.
      
    2. Restart the system.

     

    Method 2 (use a managed deployment script):

    1. Create a text file named SMBv1-disable.reg that contains the following text:
      [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters]
      "SMB1"=dword:00000000
      
    2. Run regedit.exe.
    3. In Registry Editor, click the File menu and then click Import.
    4. Navigate to and select the SMBv1-disable.reg file that you created in the first step.
      (Note If your file is not listed where you expect it to be, ensure that it has not been automatically given a .txt file extension, or change the dialog’s file extension parameters to All Files).
    5. Click Open and then click OK to close Registry Editor.
    6. Restart the system.

     

    Impact of workaround. SMB may not work properly.

    How to undo the workaround. 

    Method 1 (using PowerShell):

    1. On Windows Vista and Windows Server 2008 with PowerShell 2.0 or newer, you can execute the following PowerShell command:
      Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" SMB1 -Type DWORD -Value 1 –Force.
      
    2. Restart the system.

     

    Method 2 (use a managed deployment script):

    1. Create a text file named SMBv1-enable.reg that contains the following text:
      [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters]
      "SMB1"=dword:00000001
      
    2. Run regedit.exe.
    3. In Registry Editor, click the File menu and then click Import.
    4. Navigate to and select the SMBv1-enable.reg file that you created in the first step.
      (Note If your file is not listed where you expect it to be, ensure that it has not been automatically given a .txt file extension, or change the dialog’s file extension parameters to All Files).
    5. Click Open and then click OK to close Registry Editor.
    6. Restart the system.

       

  • Disable Extended Protection for Authentication in SMB

    Note Before you set any hardening modes, refer to the following MSDN article: Extended Protection for Authentication Overview

    1. Click Start, click Run, type Regedit in the Open box, and then click OK.
    2. Navigate to the following registry location:
      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
      
    3. On the Edit menu, select New, and then click DWORD Value.
    4. Type "SmbServerNameHardeningLevel", and then press Enter.
    5. On the Edit menu, click Modify.
    6. Set the value of SmbServerNameHardeningLevel to 0, and then click OK.
    7. Close Registry Editor and restart the system.

       

    Impact of workaround. SMB may not work properly.

    How to undo the workaround

    1. Click Start, click Run, type Regedit in the Open box, and then click OK.
    2. Navigate to the following registry location:
      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
      
    3. Select "SmbServerNameHardeningLevel", and then press Enter.
    4. On the Edit menu, click Delete, and then click Yes.
    5. Close Registry Editor and restart the system.

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 (August 11, 2015): Bulletin published.
  • V2.0 (September 8, 2015): To comprehensively address CVE-2015-2472, Microsoft re-released security update 3073921 for affected editions of Windows Vista and Windows Server 2008. Customers running Windows Vista or Windows Server 2008 who previously installed the update should reinstall the update to be fully protected from the vulnerability. See Microsoft Knowledge Base Article 3073921 for more information.

Page generated 2015-09-08 09:23-07:00.
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