Re: Possibly, but...
Hacking critical infrastructure could lead to multiple loss-of-life events. If they manage to hack the control system for a dam, nuclear plant, chemical plant (etc)...
The key thing is to keep these controls as isolated as you can, and also have local staff with local abilities to over-ride the remote stuff, and also design safeguards around problems. Take a dam - emergency spillway that means the dam won't breach, a simple physical channel that cannot be opened or closed, it simply is. The tops of your spillway gates also allow water to safely overflow should a slip close the emergency spillway and for some reason you cannot open the normal gates. Turbines that can have the maximum imaginable flow of water directed to them and still be safe, not relying on brakes that may fail to keep things in control.
So what can I do? If I shut down all systems at the dam so no spillway gates work, all the turbines etc are closed, and I blow up a chunk of hillside blocking the emergency spillway, the damn still survives.
Also have physical and automatic cutouts on your switch gear. I start trying to pull too much power through them, the contacts get open. That silly Bruce Willis movie where someone remotely sends all the natural gas in a region towards one main hub to blow it up? That should never be able to happen; flow restrictors and cut-offs or vents should be able to make sure the pipes cannot be asked to carry more gas than the weakest link can survive.
Nuke plants are much the same. Have means to start shutting them down and open up emergency cooling systems in the event of a loss of normal coolant ability. Even extra control rods that can automatically drop into place without electricity if certain parameters are exceeded (assuming I have enough understanding of how nuclear reactions are controlled - there is a very good chance that I may not :) )
There should be no way to remotely mess with things and cause problems, and very little chance even directly, short of liberal applications of C4...