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Summary

This security update for the Microsoft .NET Framework resolves a security feature bypass vulnerability in which the .NET Framework (and the .NET Core) components do not completely validate certificates. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2017-0248.

This update also contains security-enhancing fixes to the Windows Presentation Framework PackageDigitalSignatureManager component's ability to sign packages with the SHA256 hash algorithm.

Important

  • 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.

Additional information about this security update

Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

  • Enhanced Key Usage (EKU) is described in RFC 5280 in section 4.2.1.12: This extension indicates one or more purposes for which the certified public key may be used, in addition to or in place of the basic purposes that are indicated in the key usage extension. For example, a certificate that’s used for the authentication of a client to a server must be configured for Client Authentication. Similarly, a certificate that’s used for the authentication of a server must be configured for Server Authentication.

    When certificates are used for authentication, the authenticator examines the client certificate and seeks the correct purpose object identifier in Application Policies extensions. For example, the object identifier for Client Authentication is 1.3.6.1.5.5.7.3.2. When a certificate is used for client authentication, this object identifier must be present in the EKU extensions of the certificate or authentication fails. Certificates that have no EKU extension continue to authenticate correctly.

    If you can’t access correctly reissued certificates temporarily, you can choose to opt in or out of the security change across all computer operations to avoid any connectivity effects. To do this, specify the following registry key settings, depending on which .NET Framework version your application is targeting.

    Method 1: Updating registry key (available for all versions)

    Note This registry entry must be a DWORD entry.

    • For 32-bit process on 32-bit system and 64-bit process on 64-bit system:

      HKEY_LOCAL_MACHINE\Software\Microsoft\.NETFramework\v2.0.50727@RequireCertificateEKUs=0

    • For 32-bit process on 64-bit system:

      HKEY_LOCAL_MACHINE \Software\Wow6432Node\Microsoft\.NETFramework\v2.0.50727@RequireCertificateEKUs=0

    You can also opt out on a per-application basis. The following options are available for disabling this change to make sure that application compatibility is maintained.

    Method 2: Disable the policy for individual applications

    Note This registry entry must be a DWORD entry. The only valid value is 0. Any other value is ignored.

    • For 32-bit process on 32-bit system and 64-bit process on 64-bit system:

      HKEY_LOCAL_MACHINE\Software\Microsoft\.NETFramework\v2.0.50727@System.Net.ServicePointManager.RequireCertificateEKUs
      S:\Prj\console_pg\console_pg45\bin\Release\console_pg45.exe=0
      C:\MyApp\MyApp.exe=0

    • For 32-bit process on 64-bit system:

      HKEY_LOCAL_MACHINE \Software\Wow6432Node\Microsoft\.NETFramework\v2.0.50727@System.Net.ServicePointManager.RequireCertificateEKUs
      S:\Prj\console_pg\console_pg45\bin\Release\console_pg45.exe=0
      C:\MyApp\MyApp.exe=0

    Method 3: Using configuration API (available for the .NET Framework 4.6 and later versions)

    Starting in the .NET Framework 4.6, you can change the configuration at an application level through code, an application configuration, or registry changes.

    Configuring the switch in the .NET Framework 4.6

    Note The following examples disable the security feature.

    • Programmatically

      The first thing that the application should do is run the following code. This is because Service Point Manager initializes only one time.
        private const string DisableCachingName = @"TestSwitch.LocalAppContext.DisableCaching"; private const string DontCheckCertificateEKUsName= @"Switch.System.Net.DontCheckCertificateEKUs"; AppContext.SetSwitch(DisableCachingName, true); AppContext.SetSwitch(DontCheckCertificateEKUsName, true);

    • Application configuration

      To change the application configuration, add the following entry:
        <runtime> <AppContextSwitchOverrides value="Switch.System.Net.DontCheckCertificateEKUsName=true"/> </runtime>

    • Registry key (machine global):

      Registry location: HKEY_LOCAL_MACHINE\Software\[Wow6432Node\]Microsoft\.NETFramework\AppContext\Switch.System.Net.DontCheckCertificateEKUsName

      Type: String
      Value: "true"

    Note By default, Switch.System.Net.DontCheckCertificateEKUsName = True for all .NET Framework 4.x applications that are running on the .NET Framework 4.6 and later versions.

  • For more information about this security update as it relates to Windows 7 Service Pack 1 and Windows Server 2008 R2 Service Pack 1, see the following article in the Microsoft Knowledge Base:

    4019108 Security Only update for the .NET Framework 3.5.1, 4.5.2, 4.6, 4.6.1, and 4.6.2 updates for Windows 7 Service Pack 1 and Windows Server 2008 R2 Service Pack 1: May 9, 2017

How to obtain and install the update

Method 1: Microsoft Update Catalog

To get the stand-alone package for this update, go to the Microsoft Update Catalog.
 

Method 2: Windows Software Update Services (WSUS)

On your WSUS server, follow these steps:

  1. Click Start, click Administrative Tools, and then click Microsoft Windows Server Update Services 3.0.

  2. Expand ComputerName, and then click Action.

  3. Click Import Updates.

  4. WSUS will open a browser window in which you may be prompted to install an ActiveX control. You must install the ActiveX control to continue.

  5. Once the control is installed, you will see the Microsoft Update Catalog screen. Enter 4019108 in the Search box, and then click Search.

  6. Locate the .NET Framework packages that match the operating systems, languages, and processors in your environment. Click Add to add them to your basket.

  7. When you have selected all the packages that you need, click View Basket.

  8. Click Import to import the packages to your WSUS server.

  9. Click Close once the packages have been imported to return to WSUS.

The updates are now available for installation through WSUS.

Update deployment information

For deployment details for this security update, go to the following article in the Microsoft Knowledge Base:

20170509 Security update deployment information: May 9, 2017

Update removal information

Note We do not recommend that you remove any security update.

To remove this update, use the Programs and Features item in Control Panel.

Update restart information

This update does not require a system restart after you apply it unless files that are being updated are locked or are being used.

Update replacement information

This update does not replace any previously released update.

File information

Package Name

Package Hash SHA 1

Package Hash SHA 2

Windows6.1-KB4014579-x64.msu

897DDA33BA1EAB4FF67D8FF52FFF9982EE12694D

CFAAA6F614A249CA926127F63DBF2C63CCA279750F76F46C3FD8729647FD5EEB

Windows6.1-KB4014579-x86.msu

0D5BB46A5F5E0C00330E0EE14590AE20565051B9

418C9AC8E610515E3CFBDD37F4558E460A856D37861C82C9F04F82BC008665BB


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

For all x86-based systems

File name

File version

File size

Date

Time

presentationframework.dll

3.0.6920.8773

5,283,840

29-Mar-2017

13:05

reachframework.dll

3.0.6920.8773

532,480

29-Mar-2017

13:05

system.security.dll

2.0.50727.8759

270,336

28-Mar-2017

13:05

system.dll

2.0.50727.8759

3,203,072

28-Mar-2017

13:05

windowsbase.dll

3.0.6920.8773

1,257,472

29-Mar-2017

13:05

big5.nlp

66,728

23-Mar-2016

22:39

bopomofo.nlp

82,172

23-Mar-2016

22:39

ksc.nlp

116,756

23-Mar-2016

22:39

mscorlib.dll

2.0.50727.8669

4,554,752

23-Mar-2016

22:39

normidna.nlp

59,342

23-Mar-2016

22:39

normnfc.nlp

45,794

23-Mar-2016

22:39

normnfd.nlp

39,284

23-Mar-2016

22:39

normnfkc.nlp

66,384

23-Mar-2016

22:39

normnfkd.nlp

60,294

23-Mar-2016

22:39

prc.nlp

83,748

23-Mar-2016

22:39

prcp.nlp

83,748

23-Mar-2016

22:39

sortkey.nlp

262,148

23-Mar-2016

22:39

sorttbls.nlp

20,320

23-Mar-2016

22:39

xjis.nlp

28,288

23-Mar-2016

22:39

mscordacwks.dll

2.0.50727.8669

990,360

23-Mar-2016

22:39

mscorwks.dll

2.0.50727.8669

5,947,440

23-Mar-2016

22:39

sos.dll

2.0.50727.8669

391,208

23-Mar-2016

22:39

presentationcore.dll

3.0.6920.8773

4,222,976

29-Mar-2017

13:05

presentationfontcache.exe.config

161

23-Mar-2016

22:38

wpfgfx_v0300.dll

3.0.6920.8773

1,737,888

29-Mar-2017

13:05

system.printing.dll

3.0.6920.8773

372,736

29-Mar-2017

13:05

penimc.dll

3.0.6920.8773

68,752

29-Mar-2017

13:05

presentationframework.dll

3.0.6920.8773

5,283,840

29-Mar-2017

13:05

presentationhostdll.dll

3.0.6920.8773

131,248

29-Mar-2017

13:05

reachframework.dll

3.0.6920.8773

532,480

29-Mar-2017

13:05

windowsbase.dll

3.0.6920.8773

1,257,472

29-Mar-2017

13:05

For all x64-based systems

File name

File version

File size

Date

Time

big5.nlp

66,728

23-Mar-2016

22:39

bopomofo.nlp

82,172

23-Mar-2016

22:39

ksc.nlp

116,756

23-Mar-2016

22:39

mscorlib.dll

2.0.50727.8669

4,571,136

23-Mar-2016

22:39

normidna.nlp

59,342

23-Mar-2016

22:40

normnfc.nlp

45,794

23-Mar-2016

22:40

normnfd.nlp

39,284

23-Mar-2016

22:40

normnfkc.nlp

66,384

23-Mar-2016

22:40

normnfkd.nlp

60,294

23-Mar-2016

22:40

prc.nlp

83,748

23-Mar-2016

22:40

prcp.nlp

83,748

23-Mar-2016

22:40

sortkey.nlp

262,148

23-Mar-2016

22:40

sorttbls.nlp

20,320

23-Mar-2016

22:40

xjis.nlp

28,288

23-Mar-2016

22:40

mscordacwks.dll

2.0.50727.8669

1,757,336

23-Mar-2016

22:39

mscorwks.dll

2.0.50727.8669

10,008,624

23-Mar-2016

22:39

sos.dll

2.0.50727.8669

486,024

23-Mar-2016

22:40

system.security.dll

2.0.50727.8759

270,336

28-Mar-2017

13:05

system.dll

2.0.50727.8759

3,203,072

28-Mar-2017

13:05

presentationcore.dll

3.0.6920.8773

4,006,400

29-Mar-2017

13:05

presentationfontcache.exe.config

161

23-Mar-2016

22:39

wpfgfx_v0300.dll

3.0.6920.8773

2,256,032

29-Mar-2017

13:05

system.printing.dll

3.0.6920.8773

358,400

29-Mar-2017

13:05

penimc.dll

3.0.6920.8773

85,648

29-Mar-2017

13:05

presentationframework.dll

3.0.6920.8773

4,640,768

29-Mar-2017

13:05

presentationhostdll.dll

3.0.6920.8773

172,208

29-Mar-2017

13:05

reachframework.dll

3.0.6920.8773

532,480

29-Mar-2017

13:05

windowsbase.dll

3.0.6920.8773

1,118,208

29-Mar-2017

13:05

presentationframework.dll

3.0.6920.8773

5,283,840

29-Mar-2017

13:05

reachframework.dll

3.0.6920.8773

532,480

29-Mar-2017

13:05

system.security.dll

2.0.50727.8759

270,336

28-Mar-2017

13:05

system.dll

2.0.50727.8759

3,203,072

28-Mar-2017

13:05

windowsbase.dll

3.0.6920.8773

1,257,472

29-Mar-2017

13:05

big5.nlp

66,728

23-Mar-2016

22:39

bopomofo.nlp

82,172

23-Mar-2016

22:39

ksc.nlp

116,756

23-Mar-2016

22:39

mscorlib.dll

2.0.50727.8669

4,554,752

23-Mar-2016

22:39

normidna.nlp

59,342

23-Mar-2016

22:39

normnfc.nlp

45,794

23-Mar-2016

22:39

normnfd.nlp

39,284

23-Mar-2016

22:39

normnfkc.nlp

66,384

23-Mar-2016

22:39

normnfkd.nlp

60,294

23-Mar-2016

22:39

prc.nlp

83,748

23-Mar-2016

22:39

prcp.nlp

83,748

23-Mar-2016

22:39

sortkey.nlp

262,148

23-Mar-2016

22:39

sorttbls.nlp

20,320

23-Mar-2016

22:39

xjis.nlp

28,288

23-Mar-2016

22:39

mscordacwks.dll

2.0.50727.8669

990,360

23-Mar-2016

22:39

mscorwks.dll

2.0.50727.8669

5,947,440

23-Mar-2016

22:39

sos.dll

2.0.50727.8669

391,208

23-Mar-2016

22:39

presentationcore.dll

3.0.6920.8773

4,222,976

29-Mar-2017

13:05

presentationfontcache.exe.config

161

23-Mar-2016

22:38

wpfgfx_v0300.dll

3.0.6920.8773

1,737,888

29-Mar-2017

13:05

system.printing.dll

3.0.6920.8773

372,736

29-Mar-2017

13:05

penimc.dll

3.0.6920.8773

68,752

29-Mar-2017

13:05

presentationframework.dll

3.0.6920.8773

5,283,840

29-Mar-2017

13:05

presentationhostdll.dll

3.0.6920.8773

131,248

29-Mar-2017

13:05

reachframework.dll

3.0.6920.8773

532,480

29-Mar-2017

13:05

windowsbase.dll

3.0.6920.8773

1,257,472

29-Mar-2017

13:05

 

How to obtain help and support for this security update

Applies to

This article applies to the following:

 

  • Microsoft .NET Framework 3.5.1 when used with:

    • Windows Server 2008 R2 Service Pack 1

    • Windows 7 Service Pack 1

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