"A hacker with a laptop watches a crowd of people from a distance, presses a button and 10 people grip their chests and drop dead."


At the Breakpoint security conference in Melbourne last month, Mr Jack demonstrated how he was able to deliver a deadly 830-volt jolt to a pacemaker by logging into it remotely after hacking it, but did not reveal which models were vulnerable, a standard practice for ethical hackers, known as "white hats".