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MS16-077: Security update for WPAD: June 14, 2016

Summary
This security update resolves vulnerabilities in Microsoft Windows. The vulnerabilities could allow elevation of privilege if the Web Proxy Auto Discovery (WPAD) protocol falls back to a vulnerable proxy discovery process on a target system.

To learn more about the vulnerability, see Microsoft Security Bulletin MS16-077.
More information
Important
  • All future security and non-security updates for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 require update 2919355 to be installed. We recommend that you install update 2919355 on your Windows RT 8.1-based, Windows 8.1-based, or Windows Server 2012 R2-based computer so that you receive future updates.
  • If you install a language pack after you install this update, you must reinstall this update. Therefore, we recommend that you install any language packs that you need before you install this update. For more information, see Add language packs to Windows.
  • This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
    322756How to back up and restore the registry in Windows

Note You must restart the computer after you make any of the registry changes described in the following section in order for the changes to take effect.

Behavior changes after installation

After you install this security update, the following changes are applied:
  • The computer does not respond to NetBIOS name resolution requests from IP addresses that are not on the same subnet.
  • The computer does not respond to nbtstat -a or nbtstat -A requests from IP addresses that are not on the same subnet.
  • NETBIOS communication outside of the local subnet is hardened. Therefore, by default, some features that depend on NETBIOS (such as SMB over NETBIOS) will not work outside the local subnet. To change this new default behavior, create the following registry entry:
    SUBKEY: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetBT\Parameters
    Value Name: AllowNBToInternet
    Type: Dword
    Value: 1
    Default value of the flag: 0
  • By default, WPAD resolution for auto proxy detection will not use NETBIOS. Therefore, if proxy detection depends on NETBIOS alone for WPAD resolution, it may fail. We recommend that you use the DHCP option or DNS for WPAD resolution instead of NETBIOS. To change this new default behavior, create the following registry entry.

    Note This registry entry only applies for Windows 8.1 and earlier versions of Windows.
    SUBKEY: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp
    Value Name: AllowOnlyDNSQueryForWPAD
    Type: DWORD
    Value: 0
    Default value of the flag: 1
  • The default behavior of PAC file download is changed so that the client's domain credentials are not automatically sent in response to an NTLM or Negotiate Authentication challenge when WinHTTP requests the PAC file. This occurs regardless of the value of the fAutoLogonIfChallenged flag that is specified in WINHTTP_AUTOPROXY_OPTIONS. To change this new default behavior, create both of the following registry entries: 

    SUBKEY: HKEY_LOCAL_MACHINE\SOFTWARE\WoW6432Node\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp
    Value Name: AutoProxyAutoLogonIfChallenged
    Type: DWORD
    Value: 1
    Default value of the flag: 0

    SUBKEY: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp
    Value Name: AutoProxyAutoLogonIfChallenged
    Type: DWORD
    Value: 1
    Default value of the flag: 0
Additional information about this security update
The following articles contain additional information about this security update as it relates to individual product versions. The articles may contain known issue information.
  • 3161949 MS16-077: Description of the security update for WPAD: June 14, 2016
  • 3163017 Cumulative update for Windows 10: June 14, 2016
  • 3163018 Cumulative update for Windows 10 Version 1511 and Windows Server 2016 Technical Preview 4: June 14, 2016
How to obtain and install the update

Method 1: Windows Update

This update is available through Windows Update. When you turn on automatic updating, this update will be downloaded and installed automatically. For more information about how to turn on automatic updating, seeGet security updates automatically.

Note For Windows RT 8.1, this update is available through Windows Update only.

Method 2: Microsoft Download Center

You can obtain the stand-alone update package through the Microsoft Download Center. Follow the installation instructions on the download page to install the update.

Click the download link in Microsoft Security Bulletin MS16-077 that corresponds to the version of Windows that you are running.
More information

Security update deployment information

Windows Vista (all editions)

Reference Table

The following table contains the security update information for this software.

Security update file namesFor all supported 32-bit editions of Windows Vista:
Windows6.0-KB3161949-x86.msu
For all supported x64-based editions of Windows Vista:
Windows6.0-KB3161949-x64.msu
Installation switchesSee Microsoft Knowledge Base article 934307
Restart requirementYou must restart the system after you apply this security update.
Removal informationTo uninstall an update that is installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, click Installed updates under See also, and then select from the list of updates.
File informationSee Microsoft Knowledge Base article 3161949
Registry key verificationNote There is no registry key to validate the presence of this update.

Windows Server 2008 (all editions)

Reference Table

The following table contains the security update information for this software.
Security update file namesFor all supported 32-bit editions of Windows Server 2008:
Windows6.0-KB3161949-x86.msu
For all supported x64-based editions of Windows Server 2008:
Windows6.0-KB3161949-x64.msu
For all supported Itanium-based editions of Windows Server 2008:
Windows6.0-KB3161949-ia64.msu
Installation switchesSee Microsoft Knowledge Base article 934307
Restart requirementYou must restart the system after you apply this security update.
Removal informationTo uninstall an update that is installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, click Installed updates under See also, and then select from the list of updates.
File informationSee Microsoft Knowledge Base article 3161949
Registry key verificationNote There is no registry key to validate the presence of this update.

Windows 7 (all editions)

Reference Table

The following table contains the security update information for this software.
Security update file nameFor all supported 32-bit editions of Windows 7:
Windows6.1-KB3161949-x86.msu
For all supported x64-based editions of Windows 7:
Windows6.1-KB3161949-x64.msu
Installation switchesSee Microsoft Knowledge Base article 934307
Restart requirementYou must restart the system after you apply this security update.
Removal informationTo uninstall an update that is installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, click Installed updates under See also, and then select from the list of updates.
File informationSee Microsoft Knowledge Base article 3161949
Registry key verificationNote There is no registry key to validate the presence of this update.

Windows Server 2008 R2 (all editions)

Reference Table

The following table contains the security update information for this software.
Security update file nameFor all supported x64-based editions of Windows Server 2008 R2:
Windows6.1-KB3161949-x64.msu
For all supported Itanium-based editions of Windows Server 2008 R2:
Windows6.1-KB3161949-ia64.msu
Installation switchesSee Microsoft Knowledge Base article 934307
Restart requirementYou must restart the system after you apply this security update.
Removal informationTo uninstall an update that is installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, click Installed updates under See also, and then select from the list of updates.
File informationSee Microsoft Knowledge Base article 3161949
Registry key verificationNote There is no registry key to validate the presence of this update.

Windows 8.1 (all editions)

Reference Table

The following table contains the security update information for this software.

Security update file nameFor all supported 32-bit editions of Windows 8.1:
Windows8.1-KB3161949-x86.msu
For all supported x64-based editions of Windows 8.1:
Windows8.1-KB3161949-x64.msu
Installation switchesSee Microsoft Knowledge Base article 934307
Restart requirementYou must restart the system after you apply this security update.
Removal informationTo uninstall an update that is installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, click Installed updates under See also, and then select from the list of updates.
File informationSee Microsoft Knowledge Base article 3161949
Registry key verificationNote There is no registry key to validate the presence of this update.

Windows Server 2012 and Windows Server 2012 R2 (all editions)

Reference Table

The following table contains the security update information for this software.

Security update file nameFor all supported editions of Windows Server 2012:
Windows8-RT-KB3161949-x64.msu
For all supported editions of Windows Server 2012 R2:
Windows8.1-KB3161949-x64.msu
Installation switchesSee Microsoft Knowledge Base article 934307
Restart requirementYou must restart the system after you apply this security update.
Removal informationTo uninstall an update that is installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, click Installed updates under See also, and then select from the list of updates.
File informationSee Microsoft Knowledge Base article 3161949
Registry key verificationNote There is no registry key to validate the presence of this update.

Windows RT 8.1 (all editions)

Reference Table

The following table contains the security update information for this software.

DeploymentThese updates are available via Windows Update only.
Restart RequirementYou must restart the system after you apply this security update.
Removal InformationClick Control Panel, click System and Security, click Windows Update, click Installed updates under See also, and then select from the list of updates.
File InformationSee Microsoft Knowledge Base article 3161949

Windows 10 (all editions)

Reference Table

The following table contains the security update information for this software.

Security update file nameFor all supported 32-bit editions of Windows 10:
Windows10.0-KB3163017-x86.msu
For all supported x64-based editions of Windows 10:
Windows10.0-KB3163017-x64.msu
For all supported 32-bit editions of Windows 10 Version 1511:
Windows10.0-KB3163018-x86.msu
For all supported x64-based editions of Windows 10 Version 1511:
Windows10.0-KB3163018-x64.msu
Installation switchesSee Microsoft Knowledge Base article 934307
Restart requirementYou must restart the system after you apply this security update.
Removal informationTo uninstall an update that is installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, click Installed updates under See also, and then select from the list of updates.
File informationSee Microsoft Knowledge Base article 3163017
See Microsoft Knowledge Base article 3163018
Registry key verificationNote There is no registry key to validate the presence of this update.

How to obtain help and support for this security update

Help for installing updates: Support for Microsoft Update

Security solutions for IT professionals: TechNet Security Troubleshooting and Support

Help for protecting your Windows-based computer from viruses and malware: Virus Solution and Security Center

Local support according to your country: International Support
malicious attacker exploit

for scenarios where AllowNBToInternet=1 will help: Samba NTLM
Properties

Article ID: 3165191 - Last Review: 09/22/2016 20:12:00 - Revision: 4.0

Windows 10, Windows 10 Version 1511, Windows Server 2012 R2 Datacenter, Windows Server 2012 R2 Standard, Windows Server 2012 R2 Essentials, Windows Server 2012 R2 Foundation, Windows 8.1 Enterprise, Windows 8.1 Pro, Windows 8.1, Windows RT 8.1, Windows Server 2012 Datacenter, Windows Server 2012 Standard, Windows Server 2012 Essentials, Windows Server 2012 Foundation, Windows Server 2008 R2 Service Pack 1, Windows 7 Service Pack 1, Windows Server 2008 Service Pack 2, Windows Vista Service Pack 2

  • atdownload kbbug kbexpertiseinter kbfix kbsecbulletin kbsecurity kbsecvulnerability kbregistry KB3165191
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