Terrorism includes attacks on infrastructure, not just bodily harm. Firebombing an empty building still counts. In this case, it would fall specifically within cyber terrorism.

>the premeditated use of disruptive activities, or the threat thereof, against computers and/or networks, with the intention to cause harm or further social, ideological, religious, political or similar objectives. Or to intimidate any person in furtherance of such objectives

https://en.wikipedia.org/wiki/Cyberterrorism#Defining_cybert...