One of the more interesting things in recent history is that there has so far not been a really serious cyber-terrorism attack. I am unsure whether there have been real attempts that have been foiled, or whether there has been a lack of imagination.
The fact remains however that in our interconnected world, and really low online security, it can only be a matter of time before someone sees how easy it is to attack major infrastructure causing real-life damage to a country you have a grudge against.
This film from 2008 looks at the dangers that are ever present in our connected world, and some of the people involved in securing the systems, and others in trying to hack them, either for good, as with white hat hackers, or for bad with black hat hackers.
The film does expose some of the viruses and worms that have been written and unleashed on unprepared companies and individuals, and tries to link the East Coast (of the US) blackout in 2007 to the Blaster virus, but it is not sure it really was connected.
The fact is the way the internet is built and used it is not resistant to malicious actors, be they terrorists who could disrupt infrastructure, corporations who take our data, governments who surveil their populations, or cyber-bullying by peers.
A redesign of essential features, especially at the protocol level, is really needed, now we know the sorts of problems that occur. But there will be resistance from those who benefit from the present lack of privacy and security.