NEW YORK - The websites for Visa and MasterCard were inaccessible for parts of Wednesday, likely the result of attacks by WikiLeaks supporters who are angry that the credit card companies had stopped processing donations to the organization.
Both MasterCard and Visa said that cardholders’ accounts were not at risk and that people could continue using their credit cards throughout the day.
Supporters of the WikiLeaks, which has released thousands of classified government documents in recent weeks, said they would attack companies and groups hostile to the site and its founder. An Internet group operating under the label “Operation Payback” claimed responsibility for the MasterCard and Visa problems in messages on Twitter and elsewhere. MasterCard’s troubles began in early morning Eastern time and by midafternoon, its website was once again operational. But the hacker group appeared to be preparing for its next target, Visa Inc., and later in the day the company’s corporate website was inaccessible. Spokesman Ted Carr said Visa’s processing network, which handles cardholder transactions, was working normally.
The hacking group Anonymous, known for previous attacks on the Church of Scientology and Kiss bassist Gene Simmons, is distributing software tools to allow anyone with a computer and an Internet connection to join in the attacks as part of “Operation Payback.” Such tools are widely available on the Internet and can easily launch a large number of attacks on targeted websites, said Dean Turner from the computer security firm Symantec.
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MasterCard acknowledged “a service disruption” involving its Secure Code system for verifying online payments, but spokesman James Issokson said consumers could still use their credit cards for secure transactions.