Mafiaboy – DDos attack

A 15-year-old called Michael Calce carried out a distributed denial-of-service (DDoS) assault on many high-profile websites around the turn of the century. Michael Calce (also known as MafiaBoy) is a security expert and former computer hacker from Île Bizard, Quebec, who launched a series of highly publicized denial-of-service attacks against large commercial websites in February 2000, including Yahoo!, Fifa.com, Amazon.com, Dell, Inc., E*TRADE, eBay, and CNN. He also tried and failed to target nine of the thirteen root name servers at the same time. Calce, who went by the online handle Mafiaboy, exploited a series of university networks to flood these sites with data, costing corporations $1 billion (£801 million) to becoming one of the most expensive cyber attacks at that time.

"Government and commercial computer systems are so inadequately safeguarded today that they may virtually be regarded vulnerable - an Electronic Pearl Harbor waiting to happen," computer specialist Winn Schwartau said during a hearing before members of the US Congress. The notion that a 15-year-old could make the world's largest website unavailable caused significant worry. The internet had already become an important element of the North American economy at this point. Consumers lost faith in internet commerce, and the American economy took a hit as a result. Craig Guent, a former CIA operative, attributes the major gain in online security over the last decade to Mafiaboy.

Cost: £801 million