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

• 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:
  
  322756 How to back up and restore the registry in Windows

Behavior changes after installation

• 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
  
  
  
  
  

• 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