The prospect of “cyberwar” - the use of computers to carry out attacks on either government or commercial networks – is increasingly real.

There are two main threats: industrial espionage, where hackers based in foreign countries attempt to break into networks to steal company secrets, and attacks designed to cause widespread social disruption.

Terrorists using computer-hacking techniques are more likely to be intent on bringing down the networks that run essential services, including power, water and other utilities, as well as banking and telecommunications systems. All of these rely on interconnected computer networks, which, if not protected, are prone to being infiltrated by hackers.

The techniques used by exponents of cyber-war are constantly evolving. One common attack is known as a distributed denial of service attack, where hackers employ vast armies of “zombie” computers – many of them standard PCs whose owners are unaware that they have been coopted – to carry out attacks.

More sophisticated hackers try to carry out what is known as network intrusion, where a company’s computer system is infiltrated via a “port” that is connected to the internet. Once inside, hackers can begin downloading information or carry out more sophisticated attacks. They typically use a piece of software known as a trojan, which enables their computers to talk to the compromised network.

Techniques for guarding against cyber-attacks are improving, but hackers become more wily. “Attackers keep modifying their behaviour to try to counter security efforts,” Paul Vlissidis, from NCC Group, said. “While technology will defeat many of them, there are also a lot of poor software programmers out there. As long as there are poor programmers, these types of attacks will continue.”

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