Description of the Security and Quality Rollup for .NET Framework 4.6 on Windows Server 2008 SP2 (KB 4055002)

Applies to: .NET Framework 4.6

Summary


This security update resolves a security feature bypass vulnerability that exists when Microsoft .NET Framework and .NET Core components do not completely validate certificates. This security update addresses the vulnerability by helping to make sure that .NET Framework and .NET Core components completely validate certificates. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-0786.

Additionally, this security update resolves a denial of service vulnerability that exists when .NET Framework and .NET Core components process XML documents incorrectly. This update addresses the vulnerability by correcting how .NET Framework and .NET Core component applications handle XML document processing. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-0764.

Important

  • All updates for .NET Framework 4.6 require that the d3dcompiler_47.dll update be installed. We recommend that you install the included d3dcompiler_47.dll update before you apply this update. For more information about the d3dcompiler_47.dll update, see KB 4019478 for Windows Server 2008 SP2.
  • 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


  • 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 instead of the basic purposes that are indicated in the key usage extension. For example, a certificate that is used for the authentication of a client to a server must be configured for Client Authentication. Similarly, a certificate that is used for the authentication of a server must be configured for Server Authentication. This update changes this process so that the certificate chain validation fails if the root certificate is disabled. This is in addition to requiring the appropriate client or server EKU on certificates.

    If certificates are used for authentication, the authenticator examines the certificate that is provided by the remote endpoint and looks for the correct purpose object identifier in Application Policies extensions. If a certificate is used for client authentication, the object identifier for Client Authentication must be present in the EKU extensions of the certificate, or authentication fails. The object identifier for Client Authentication is 1.3.6.1.5.5.7.3.2. Likewise, when a certificate is used for server authentication, the object identifier for Server Authentication must be present in the EKU extensions of the certificate, or authentication fails. The object identifier for Server Authentication is 1.3.6.1.5.5.7.3.1. Certificates that have no EKU extension continue to authenticate correctly.

    Consider making changes to your component’s certificates to make sure that they are using the correct EKU OID attributes and are secured correctly. If you temporarily cannot access correctly reissued certificates, you can choose to opt in or out of the security change to avoid any connectivity effects. To do this, specify the following appsetting value in the configuration file:
    <appSettings>    <add key="wcf:useLegacyCertificateUsagePolicy" value="true" /></appSettings>
    Note Setting the value to “true” will opt out of the security changes.
  • For more information about this security update as it relates to Windows Server 2008 SP2, see the following article in the Microsoft Knowledge Base:

4055267 Security and Quality Rollup for the .NET Framework 2.0 SP2, 3.0 SP2, 4.5.2, and 4.6 updates for Windows Server 2008 SP2 (KB 4055267)

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 opens a browser window in which you may be prompted to install an ActiveX control. You must install the ActiveX control to continue.
  5. The Microsoft Update Catalog screen opens. Enter 4055532 into 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. After you select all the packages that you require, click View Basket.
  8. Click Import to import the packages to your WSUS server.
  9. To return to WSUS, click Close after the packages are imported.

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:

20180109 Security update deployment information: January 9, 2018

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 replaces the following updates:

File information


 

How to obtain help and support for this security update