How to Restrict File Types Recognized as Possible Crypto Threats with Group Policy

Step #

Task

Screenshot

1

Log in to a PC that has The Application That File Extension Uses and Domain Administrative Tools installed.

2

From the Server Manager Screen: 

Select Tools > Group Policy Management

3

Right-click on Group Policy Projects and select New.

4

Name the new GPO Disallowed File Extensions and then, click OK.

5

In the right pane of the GPO management console, find the policy: "Disallowed File Extensions" and select Edit.

6

Navigate to Computer Configuration > Preferences > Control Panel Settings > Folder Options.

Right-click on it and choose New > File Type from the context menu.

7

From there, click the Actions drop-down menu and choose the Create option.

File extension: Enter the file extension block

Associated class: Select the application that uses this file.

Click OK to Save.

Repeat Steps 5 and 6 for each extension that needs to be entered.

Note: application must be installed on the device you are creating the GPO on or else it will not be available in the list.

8

Apply the rule to the top of the domain infrastructure so it will apply to every device on the domain.