For the first time, banks and internet companies were part of an exercise preparing EU institutions in case of a cyber attack.
Four hundred experts from across Europe faced more than 1,200 separate cyber attacks on Thursday.
The simulated threat came from a European security agency in Athens, but for those taking part, it meant coming up with coordinated reactions and defences to tackle the real danger of online attacks that can disrupt services, steal data and manipulate prices.
Krzysztof Socha from the EU Computer Emergency Response Team said: “The attacks that we have seen around the world so far were not really that big.
“We could imagine bigger attacks that would be more difficult to deal with and this is one of the reasons for the exercise: to train, to be able to deal with a really large scale DDos (Distributed Denied of Service) attacks.”
In 2011, web-based attacks increased by 36 percent, and 40 percent of them targeted financial institutions.
The final report on Thursday’s exercise will add to an EU Strategy on Cyber Security, being prepared by the European Commission and the High Representative For Foreign Affairs and Security Policy.
“It will be published by the end of this year and we will, of cause, also come with legislation in the field, and what is at stake it that it’s a common approach where we can prove that borders are not at stake,” said European Commissioner for Digital Agenda Neelie Kroes
Under current EU law, only electronic communications companies have to report security incidents and have risk management practices.
In the future, this will be extended to economic and social services like finance, energy, transport, health, e-commerce and social networking.