Information
This policy setting allows you to control how ActiveX controls in UserForms should be initialized based upon whether they are Safe For Initialization (SFI) or Unsafefor Initialization (UFI). The recommended state for this setting is: Disabled. ActiveX controls are Component Object Model (COM) objects and have unrestricted access to users' computers. ActiveX controls can access the local file system and change the registry settings of the operating system. If a malicious user repurposes an ActiveX control to take over a user's computer, the effect could be significant. To help improve security, ActiveX developers can mark controls as Safe For Initialization (SFI), which means that the developer states that the controls are safe to open and run and not capable of causing harm to any computers. If a control is not marked SFI, the control could adversely affect a computer#x2014;or it's possible the developers did not test the control in all situations and are not sure whether their control might be compromised at some future date. SFI controls run in safe mode, which limits their access to the computer. For example, a worksheet control can both read and write files when it is in unsafe mode, but perhaps only read from files when it is in safe mode. This functionality allows the control to be used in very powerful ways when safety wasn't important, but the control would still be safe for use in a Web page. If a control is not marked as SFI, it is marked Unsafe For Initialization (UFI), which means that it is capable of affecting a user's computer. If UFI ActiveX controls are loaded, they are always loaded in unsafe mode. This setting allows administrators to control how ActiveX controls in UserForms should be initialized based upon whether they are SFI or UFI.
Solution
To implement the recommended configuration state, set the following Group Policy setting to Disabled. User Configuration\Administrative Templates\Microsoft Office 2016\Security Settings\Load Controls in Forms3 Impact: Enabling this setting and selecting '2' enforces the default configuration and is therefore unlikely to cause usability issues for most users.