It is known that a "Follina exploit" RTF maldoc can lead to code execution by being viewed in Explorer's preview pane:

Word will then launch msdt.exe which will ultimately lead to calc being executed in this example:

When Word is not running, an instance is launched by the DCOM Server Process Launcher service, so that it can do the rendering of the document to be displayed in Explorer's preview pane:

During this rendering, msdt.exe is launched.

Didier Stevens
Senior handler
Microsoft MVP
blog.DidierStevens.com