A group of “hacktivists” known as Anonymous spearheaded the attacks and dubbed them “Operation Payback”.
Automated barrages by WikiLeaks’ defenders also temporarily shut down web pages controlled by other companies that have cut connections with WikiLeaks, including credit card network Visa, whose public home page was down for less than an hour. In a statement, Visa said its regular payment processing was unaffected.
MasterCard initially blamed problems with its website on heavy traffic but later said some SecureCode services had been disrupted. It reassured customers that core processing capabilities have not been compromised and cardholder account data has not been placed at risk”.
Some technology experts said the disruption of core commerical services by a few thousand individuals could prompt calls for internet service providers to take a more active role in policing their networks and blocking connections from computers identitifed as participating in what are known as denial-of-service attacks.
The official blog at PayPal, which the internet payments processor had used to explain its decision to stop handling donations to WikiLeaks, was shut by denial-of-service attacks for more than eight hours.
WikiLeaks has seen its own site come under attack from hackers and has also been forced to shift its main website to a Swiss domain after Amazon threw it off its web host. Last week EveryDNS.net, the company administering its domain name system, terminated its services.