26-year-old Slovenian hacker known as Iserdo stands thought to have been behind the Mariposa botnet is on trial in Slovenia, charged with having masterminded an international cybercrime gang.

At its height, the Mariposa botnet infected up to 12.7 million PCs, with more than half of the Fortune 1,000 companies believed to have been compromised, including 40 major banks. Once a computer had been compromised and brought into the botnet, operators could steal information from innocent users - including credit card details and banking passwords.