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Description of the Security and Quality Rollup for the .NET Framework 4.6.2 for Windows 8.1 and Windows Server 2012 R2: May 9, 2017

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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.

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Important

  • All security and nonsecurity 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 updates in the future.
  • 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.

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Additional information about this security update

  • 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 temporarily can’t access correctly reissued certificates, 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\v4.0.30319@RequireCertificateEKUs=0
    • For 32-bit process on 64-bit system:
       
      HKEY_LOCAL_MACHINE \Software\Wow6432Node\Microsoft\.NETFramework\v4.0.30319@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\v4.0.30319@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\v4.0.30319@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 to 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 8.1 and Windows Server 2012 R2, see the following article in the Microsoft Knowledge Base:

    4019114 Security and Quality Rollup for the .NET Framework 3.5 Service Pack 1, 4.5.2, 4.6, 4.6.1, and 4.6.2 updates for Windows 8.1 and Windows Server 2012 R2: May 9, 2017

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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 get security updates automatically, see Windows Update: FAQ.

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 4019114 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.

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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.

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File information

File hash
Package Name Package Hash SHA 1 Package Hash SHA 2
Windows8.1-KB4014507-arm.msu CC0CCB62CA31D9F9BD29B7C3908B03C6295E226B B271FB9647E413E514DB1172406471FD080FD29A05D6C7941EE2C7C09602AD72
Windows8.1-KB4014507-x64.msu EBBBED9223AC18FBFD2C2665A9B81C17D17EC409 E5CE3C8DA7A29760E556975F7C63A4E85AF810295B2A753EAEDA804D93499324
Windows8.1-KB4014507-x86.msu 3CFA48238702BE191831633DB286845A30BFD31F 02E9EC76E8C6AD0B21CE0033055DE1DB396A9727494BDC2597074EA7656FB903

 

 

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How to obtain help and support for this security update

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Applies to

This article applies to the following:
 
  • Microsoft .NET Framework 4.6.2 when used with:
    • Windows Server 2012 R2
    • Windows 8.1

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Keywords: kbsurveynew, kbsecvulnerability, kbsecurity, kbsecreview, kbsecbulletin, kbbug, kblangall, kbfix, kbexpertiseinter, kb, atdownload, kbmustloc

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Article Info
Article ID : 4014507
Revision : 19
Created on : 5/12/2017
Published on : 5/13/2017
Exists online : False
Views : 250