On a general note, using botnet, compromised systems are used to launch such attacks while the owners of these compromised systems possibly remain unaware of their involvement in the attacks.

Further, The Local also reported that till the evening of October 30, neither the police investigators nor the hosting firm exactly knew the reason and source of the attacks.

Technical manager at Basefarm, Stefan Månsby, stated that from the nature of the attack, it is clear that cyber criminals possess immense knowledge. The attack took place outside Europe in a well-planned manner and with a very serious approach, as reported by The Local on October 30, 2009.

Basefarm said that it did not receive any sort of threat or warning before the attack took place. An internal investigation by the firm into the attack is underway. Also, the firm is now preparing to report the matter to the police.

A separate series of attacks simultaneously hit other Swedish websites also, and among them was the Swedish police website. For a couple of hours, the attack knocked this website out of commission.

In both these attacks, the level of traffic remained same and the traffic was observed by the United States, though the attacker could be anywhere in the world.

The two attacks are closely linked with each other, believe the police IT experts. It is said that Swedish Civil Contingencies Agency (MSB) was completely alert following a 12-hr period during which news organizations and police websites have both been attacked.

To conclude, experts informed that as a form of cyber warfare and protest, these distributed denial-of-service attacks have increased in number and have gained popularity in recent years. Attackers use botnets and multiple systems to deliberately flood the websites with traffic, making the servers down and knocking sites offline for extended durations.