KB5021751 targets versions of Office "including" 2007 and 2010, which have been out of service for several years but remain popular on torrent sites. Office 2013 is mentioned because it will lose support in April.

"This update will run one time silently without installing anything on the user's device," Vole said

There is no explanation of how the update will gather info on Office installations, whether it is collecting any other system information or what exactly will be transmitted and stored by Microsoft.

Vole failed to mention if traces of the update may be left behind, but whatever it is doing it will phone home the results to the Microsoft mothership and Vole will know you're running an old Office.

Microsoft also should have mentioned what it intends to do with the data it collects from the update, though it is not difficult to guess.