Install the update

To resolve the security vulnerability, install the Windows updates and enable Enforce mode by following these steps:

Deploy the January 12, 2021 update to all client and server devices.

After all client and server devices have been updated, full protection can be enabled by setting the registry value to 1.

Step 1: Install Windows Update

Install the Windows update from January 12, 2021 or a later Windows update for all client and server devices. January 12, 2021 updates

Step 2: Enable enforce mode

Important This section, method, or task contains steps that describe how to modify the Registry. However, serious problems may occur if you modify the Registry incorrectly. Therefore, follow these steps carefully. For added protection, back up the Registry before modifying it. That way, you can restore the Registry if a problem occurs. For more information about backing up and restoring the Registry, see How to back up and restore the Registry in Windows.

After all client and server devices have been updated, you can activate full protection by deploying Enforce mode. To do this, follow these steps: Right-click Start, click Run, type cmd in the Run box and press Ctrl+Shift+Enter. At the Administrator command prompt, type regedit and press Enter. Locate the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print

Right-click Print, select New and then click DWORD (32-bit) Value.

Type:

and press Enter.

Right-click RpcAuthnLevelPrivacyEnabled and click Modify.

In the Value data box, type 1 and click OK.

Note: This update introduces support for the Registry value RpcAuthnLevelPrivacyEnabled to increase the authentication level for the printer IRemoteWinspool.

Registry subkey

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Print

Value

RpcAuthnLevelPrivacyEnabled

Data type

REG_DWORD

Data

• 1: enables Enforce mode. Before enabling server-side Enforce mode, ensure that all client devices have installed the Windows update released on January 12, 2021 or a later Windows update. This fix increases the authentication level for the printer IRemoteWinspool RPC interface and adds a new policy and registry value on the server side to force the client to use the new authentication level if Enforce mode is applied. If the client device does not have the January 12, 2021 security update or a later Windows update applied, the printing experience will break when the client connects to the server via the IRemoteWinspool interface.

• 0: not recommended. Disables the increased authentication level for the printer IRemoteWinspool and your devices are not protected.

Is a restart required? Yes, a device restart or a spooler service restart is required.

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