Reckz0r wrote on Twitter that he deleted a message containing the Visa number for Reid Hoffman, the founder of the social-networking site LinkedIn, for fear his Twitter account would be suspended.

The mix of international addresses indicates that the target could have been an international payment processor, said Dan Clements, who runs CloudeyeZ, a security consultancy that monitors underground forums for sensitive data and tries to match the data with its owner.

Those payment processors are a rich target for hackers. In April, the payment processor Global Payments said hackers stole details for 1.5 million credit and debit cards, including account numbers, card expiration dates but not names of consumers or Social Security numbers. Global Payments processes payments for about one million storefronts worldwide.