MS16-077: Description of the 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.

Behavior changes after installation

After you install this security update, the following changes are applied:
  • 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 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: AutoProxyAutoLogonIfChallenged
    Type: DWORD
    Value: 1
    Default value of the flag: 0
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

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
File Information

File hash information

File nameSHA1 hashSHA256 hash
Windows8.1-KB3161949-x86.msuA15B1E6C4E2D8C061C13AD6697340030D11300F9684F04EC92FDB71A0587910F5223F29B1B1126E69B049EA4E6C1AB3E32BCD103
Windows8.1-KB3161949-x64.msu303F894A71FAD84F147E1EE715F8C60DDFC752D739F78CC8472AA4ACB6AF6BD18CC13BDEFB9728ED71FCEE2001E063683FED2B50
Windows8-RT-KB3161949-x64.msuFD0D730F70653946886E358E989636481693750086967AF0963599C4E49835B35EF3A8A6BFA39FCBCB3C6DA378D02E70F34A023C
Windows6.0-KB3161949-x64.msuE60F107F4F893C19885931B3C6121FDDF1150E52D2F0E848E7D45C428324DD6833CE1F6B9E36F4EC0C27FA33993B482C20A870E0
Windows6.0-KB3161949-x86.msu45C230D3302716D81E413BD233F953BD6F6F1F09B45C8FB5F7E96CE551E752F67E45AAB6657B9E204C603F23AA7284BB39FA3E8D
Windows6.1-KB3161949-x86.msu0055D0D1E103D374E042F31EBDD26931853B882BF968AB471633DB7EBAF2619902CBB6246D14B14AF6E29CCA6C2981EB898DE0B7
Windows6.1-KB3161949-ia64.msu9136B0FC403D6CDCD8CF94B061953CC11723CADB7A2FFB83D4CE22325768FF94C71A9FFE839C653D1B8EA2C3BA73DDF89B2555C8
Windows6.1-KB3161949-x64.msuE2372FB5746E9474CEC6EF1710F8D58EC5C6C0007CFC5DCDDD7A72E1CB143E41A98D5EAF23CE554104F05311EFD8B317BCE8E847
Windows6.0-KB3161949-ia64.msu2F913DA164CBAD6FD4331A9D06BA3F457EC6887F540668B9660A8CD03240B7DCF84A9DFAEBCCBE3C4661340389FB0A049F317825

File information

The English (United States) version of this software update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). Be aware that dates and times for these files on your local computer are displayed in your local time and with your current daylight saving time bias. The dates and times may also change when you perform certain operations on the files.

Windows 8.1 and Windows Server 2012 R2 file information

Notes
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    VersionProductMilestoneService branch
    6.3.960 0.16 xxxWindows RT 8.1, Windows 8.1, and Windows Server 2012 R2RTMGDR
    6.3.960 0.17 xxxWindows RT 8.1, Windows 8.1, and Windows Server 2012 R2RTMGDR
    6.3.960 0.18 xxxWindows RT 8.1, Windows 8.1, and Windows Server 2012 R2RTMGDR
  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
  • The MANIFEST files (.manifest) and MUM files (.mum) that are installed are not listed.
For all supported x86-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.3.9600.18340213,50413-May-201622:22x86NoneNot applicable
Mswsock.dll6.3.9600.18340286,20813-May-201621:35x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.3.9600.18340320,72014-May-201620:01x86NoneNot applicable
Winhttp.dll6.3.9600.18340631,80813-May-201621:26x86NoneNot applicable
For all supported x64-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.3.9600.18340281,08813-May-201623:07x64NoneNot applicable
Mswsock.dll6.3.9600.18340339,45613-May-201621:58x64SP_AMD64_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.3.9600.18340363,10414-May-201620:01x64NoneNot applicable
Winhttp.dll6.3.9600.18340802,81613-May-201621:45x64NoneNot applicable
Winhttp.dll6.3.9600.18340631,80813-May-201621:26x86NoneNot applicable
Mswsock.dll6.3.9600.18340286,20813-May-201621:35x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.3.9600.18340320,72014-May-201620:01x86NoneNot applicable

Windows Server 2012 file information

Notes
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    Version Product Milestone Service branch
    6.2.920 0.17xxxWindows 8, Windows RT, or Windows Server 2012RTMGDR
    6.2.920 0.21xxxWindows 8, Windows RT, or Windows Server 2012RTMLDR
  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
  • The MANIFEST files (.manifest) and MUM files (.mum) that are installed are not listed.
For all supported x64-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.2.9200.21859318,97609-May-201613:19x64NoneNot applicable
Mswsock.dll6.2.9200.21858355,32809-May-201615:41x64SP_AMD64_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.2.9200.21858343,55209-May-201615:41x64NoneNot applicable
Winhttp.dll6.2.9200.21858711,68009-May-201615:41x64NoneNot applicable
Winhttp.dll6.2.9200.21797516,09608-Mar-201616:04x86NoneNot applicable
Mswsock.dll6.2.9200.21858288,76809-May-201616:38x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.2.9200.21858307,71209-May-201616:39x86NoneNot applicable

Windows Vista and Windows Server 2008 file information

Notes
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    Version Product Milestone Service branch
    6.0.600 2.19xxxWindows Vista or Windows Server 2008SP2GDR
    6.0.600 2.23xxxWindows Vista or Windows Server 2008SP2LDR
  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
  • The MANIFEST files (.manifest) and MUM files (.mum) that are installed are not listed.
For all supported x64-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.0.6002.19655248,32010-May-201614:55x64NoneNot applicable
Netbtugc.exe6.0.6002.1965524,06410-May-201614:55x64NoneNot applicable
Netbt.sys6.0.6002.23970248,32010-May-201614:53x64NoneNot applicable
Netbtugc.exe6.0.6002.2397024,06410-May-201614:53x64NoneNot applicable
Mswsock.dll6.0.6002.19655304,12810-May-201615:54x64SP_AMD64_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Mswsock.dll6.0.6002.23970303,61610-May-201615:34x64SP_AMD64_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.0.6002.19655264,70410-May-201615:55x64NoneNot applicable
Ws2_32.dll6.0.6002.23970264,70410-May-201615:35x64NoneNot applicable
Winhttp.dll6.0.6002.19655442,88010-May-201615:54x64NoneNot applicable
Winhttp.dll6.0.6002.23970442,88010-May-201615:35x64NoneNot applicable
Netbtugc.exe6.0.6002.1965521,50410-May-201614:28x86NoneNot applicable
Netbtugc.exe6.0.6002.2397021,50410-May-201614:28x86NoneNot applicable
Winhttp.dll6.0.6002.19655377,34410-May-201615:31x86NoneNot applicable
Winhttp.dll6.0.6002.23970377,34410-May-201615:14x86NoneNot applicable
Mswsock.dll6.0.6002.19655223,23210-May-201615:31x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Mswsock.dll6.0.6002.23970223,23210-May-201615:14x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.0.6002.19655179,20010-May-201615:31x86NoneNot applicable
Ws2_32.dll6.0.6002.23970179,20010-May-201615:14x86NoneNot applicable
For all supported x86-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.0.6002.19655185,85610-May-201614:28x86NoneNot applicable
Netbtugc.exe6.0.6002.1965521,50410-May-201614:28x86NoneNot applicable
Netbt.sys6.0.6002.23970186,36810-May-201614:28x86NoneNot applicable
Netbtugc.exe6.0.6002.2397021,50410-May-201614:28x86NoneNot applicable
Mswsock.dll6.0.6002.19655223,23210-May-201615:31x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Mswsock.dll6.0.6002.23970223,23210-May-201615:14x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.0.6002.19655179,20010-May-201615:31x86NoneNot applicable
Ws2_32.dll6.0.6002.23970179,20010-May-201615:14x86NoneNot applicable
Winhttp.dll6.0.6002.19655377,34410-May-201615:31x86NoneNot applicable
Winhttp.dll6.0.6002.23970377,34410-May-201615:14x86NoneNot applicable
For all supported ia64-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.0.6002.19655632,83210-May-201614:37IA-64NoneNot applicable
Netbtugc.exe6.0.6002.1965552,22410-May-201614:36IA-64NoneNot applicable
Netbt.sys6.0.6002.23970632,83210-May-201614:38IA-64NoneNot applicable
Netbtugc.exe6.0.6002.2397052,22410-May-201614:37IA-64NoneNot applicable
Mswsock.dll6.0.6002.19655709,63210-May-201615:23IA-64SP_IA64_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Mswsock.dll6.0.6002.23970709,12010-May-201615:12IA-64SP_IA64_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.0.6002.19655519,16810-May-201615:23IA-64NoneNot applicable
Ws2_32.dll6.0.6002.23970519,16810-May-201615:13IA-64NoneNot applicable
Winhttp.dll6.0.6002.19655962,04810-May-201615:23IA-64NoneNot applicable
Winhttp.dll6.0.6002.23970962,04810-May-201615:13IA-64NoneNot applicable
Netbtugc.exe6.0.6002.1965521,50410-May-201614:28x86NoneNot applicable
Netbtugc.exe6.0.6002.2397021,50410-May-201614:28x86NoneNot applicable
Winhttp.dll6.0.6002.19655377,34410-May-201615:31x86NoneNot applicable
Winhttp.dll6.0.6002.23970377,34410-May-201615:14x86NoneNot applicable
Mswsock.dll6.0.6002.19655223,23210-May-201615:31x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Mswsock.dll6.0.6002.23970223,23210-May-201615:14x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.0.6002.19655179,20010-May-201615:31x86NoneNot applicable
Ws2_32.dll6.0.6002.23970179,20010-May-201615:14x86NoneNot applicable

Windows 7 and Windows Server 2008 R2 file information

Notes
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    Version Product Milestone Service branch
    6.1.760 1.18xxxWindows 7 or Windows Server 2008 R2 SP1GDR
    6.1.760 1.23 xxxWindows 7 or Windows Server 2008 R2 SP1 LDR
  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
  • The MANIFEST files (.manifest) and MUM files (.mum) that are installed are not listed.
For all supported x86-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.1.7601.23451188,92811-May-201614:52x86NoneNot applicable
Netbtugc.exe6.1.7601.2345126,62411-May-201615:01x86NoneNot applicable
Mswsock.dll6.1.7601.23451231,42411-May-201615:19x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.1.7601.23451206,33611-May-201615:19x86NoneNot applicable
Winhttp.dll6.1.7601.23451351,74411-May-201615:19x86NoneNot applicable
For all supported ia64-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.1.7601.23451616,96011-May-201614:44IA-64NoneNot applicable
Netbtugc.exe6.1.7601.2345153,76011-May-201614:58IA-64NoneNot applicable
Mswsock.dll6.1.7601.23451750,59211-May-201615:13IA-64SP_IA64_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.1.7601.23451546,30411-May-201615:13IA-64NoneNot applicable
Winhttp.dll6.1.7601.23451812,03211-May-201615:13IA-64NoneNot applicable
Netbtugc.exe6.1.7601.2345126,62411-May-201615:01x86NoneNot applicable
Winhttp.dll6.1.7601.23451351,74411-May-201615:19x86NoneNot applicable
Mswsock.dll6.1.7601.23451231,42411-May-201615:19x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.1.7601.23451206,33611-May-201615:19x86NoneNot applicable
For all supported x64-based versions
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Netbt.sys6.1.7601.23451262,14411-May-201614:58x64NoneNot applicable
Netbtugc.exe6.1.7601.2345125,08811-May-201615:11x64NoneNot applicable
Mswsock.dll6.1.7601.23451327,16811-May-201617:02x64SP_AMD64_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.1.7601.23451296,44811-May-201617:02x64NoneNot applicable
Winhttp.dll6.1.7601.23451444,92811-May-201617:02x64NoneNot applicable
Netbtugc.exe6.1.7601.2345126,62411-May-201615:01x86NoneNot applicable
Winhttp.dll6.1.7601.23451351,74411-May-201615:19x86NoneNot applicable
Mswsock.dll6.1.7601.23451231,42411-May-201615:19x86SP_X86_MICROSOFT-WINDOWS-W..-INFRASTRUCTURE-BSP
Ws2_32.dll6.1.7601.23451206,33611-May-201615:19x86NoneNot applicable
malicious attacker exploit
Properties

Article ID: 3161949 - Last Review: 06/14/2016 17:30:00 - Revision: 1.0

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

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