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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 improperly process XML documents. 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 Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 require that update KB 2919355 be installed. We recommend that you install update KB 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.

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. With this change, besides requiring the appropriate client/server EKU on certificates, if the root certificate is disabled, the certificate chain validation will fail.

    When certificates are used for authentication, the authenticator examines the certificate that is provided by the remote endpoint and seeks the correct purpose object identifier in Application Policies extensions. When 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.

    First, 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 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 8.1, Windows RT 8.1, and Windows Server 2012 R2, see the following article in the Microsoft Knowledge Base:

4055271 Security Only update for .NET Framework 3.5 SP1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, and 4.7.1 updates for Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2 (KB 4055271)

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. Select Start, select Administrative Tools, and then select Microsoft Windows Server Update Services 3.0.

  2. Expand ComputerName, and then select Action.

  3. Select Import Updates.

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

  5. Once the control is installed, you will see the Microsoft Update Catalog screen. Enter 4055271 in the Search box, and then select Search.

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

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

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

  9. Select 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:

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 update KB 3122654.

File information

File hash

Package name

PackageHashSHA1

PackageHashSHA2

Windows8.1-KB4054170-x64.msu

AE77555A1AFF3DA0C4D09C9C4E10D9D97CFD0897

19B732E703AD70B33BA048CC7F7100D27F9CBD604C84B7B1C789D3215BCDB37E

Windows8.1-KB4054170-x86.msu

AA799B20BD1D5798708EB64D02A0DCB5DD4EBF58

AA8D71B9A4767451453DFB57EB587C1A333B372B9AB35955331590291A397E7B


File attributes

The English (United States) version of this hotfix 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). The dates and 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 times may change when you perform certain operations on the files.

For all x86-based systems

File name

File version

File size

Date

Time

system.xml.dll

4.0.30319.36427

2,705,040

12-Dec-2017

13:10

For all x64-based systems

File name

File version

File size

Date

Time

system.servicemodel.dll

4.0.30319.36427

6,386,368

12-Dec-2017

13:10

How to obtain help and support for this security update

Applies to

This article applies to the following:

 

  • Microsoft .NET Framework 4.5.2 when used with:

    • Windows Server 2012 R2

    • Windows 8.1

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