Critical infrastructure is the physical and digital shared systems on which citizens depend. This includes government and healthcare, energy and water networks, manufacturing and telecoms, transportation systems and financial networks. While these are disparate industries that function in very different ways, they all share a common factor: they are increasingly reliant on the internet, making them vulnerable to cyber attacks.
In the pre-internet age, a physical attack on critical infrastructure may have been considered an act of terrorism or war, and justice would be sought against the perpetrators. Yet today, organisations in these sectors face thousands of potentially devastating cyber attacks every single day and may not even be able to identify the attackers, which could include rogue nations lured by the chance to paralyse industries, terrorise the public or engage in clandestine surveillance. An advanced persistent threat (APT) can lurk undetected within computer networks for extended periods, waiting to strike. The societal importance of critical infrastructure also makes it a prime target for non-state gangs of cyber criminals using ransomware for extortion. In a period of political unrest, cyber attacks on state facilities or large organisations could also be a tactic of activist groups seeking publicity.