In December 2010, a group of nearly 3000 activists under the name "Operation Payback" launched online attacks against PayPal, MasterCard, and Visa, briefly knocking the three financial services' sites offline and preventing consumers from accessing ATMs or online banking services.
The activists retaliated against the three companies for severing ties with WikiLeaks, an online repository for whistleblower data that had recently included thousands of secret communications from the U.S. State Department and other world governmental agencies. Nine months later more than a dozen people--most between the ages of 19 and 24--were arrested in connection with these denial-of-service (DoS) attacks, even as new attacks were hitting corporate, military, and government sites worldwide.

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