7 December 2012 Last updated at 05:29 ET

Student Christopher Weatherhead guilty of cyber attacks

Victims of the cyber attacks found their websites suddenly crashed

A student has been convicted for his part in cyber attacks launched by computer hacking group Anonymous.

Christopher Weatherhead, 22, from Northampton, took part in distributed denial of service (DDoS) attacks, one of which cost website PayPal £3.5m.

The attacks paralysed firms' computer systems by flooding them with an intolerable number of online requests.

A jury of six men and five women found Weatherhead guilty after two hours of deliberations.

So-called "hacktivist" Weatherhead was a student at Northampton University when he joined the cyber campaign.

Sites including MasterCard, Visa, Ministry of Sound, the British Recorded Music Industry (BPI) and the International Federation of the Phonographic Industry (IFPI) also came under attack.

What is a DDoS attack?

• Attackers commonly use networks of compromised computers - called a botnet - that they control to launch the attacks
• Hacking group Anonymous has recruited volunteers to download a tool to create a "virtual" botnet
• By overwhelming the target site with requests, the attackers can ensure that genuine visitors cannot reach the site
• These requests look like genuine web traffic so can be hard to filter out
• Typically, such attacks have been aimed at high-profile websites, such as those belonging to government departments, banks and political organisations
• They are illegal in most countries

Victims found their websites suddenly crashed, and visitors would be directed to a page displaying the message: "You've tried to bite the Anonymous hand. You angered the hive and now you are being stung."

Southwark Crown Court heard that PayPal was attacked after it decided not to process payments on behalf of the Wau Holland Foundation, an organisation involved in raising funds for Wikileaks.

The court was told between 8 and 17 December 2010, PayPal was the victim of a series of attacks "which caused considerable damage to its reputation and loss of trade".

Weatherhead had pleaded not guilty to a charge of conspiring to impair the operation of computers between 1 August 2010 and 22 January 2011.