Yet tens of millions of Target and Neiman Marcus customers whove never shopped at those stores websites are being told their credit-card information might be in the hands of cybercriminals. When were talking about data breaches, usually the customer did nothing wrong, said Bogdan Botezatu, senior e-threat analyst at Bitdefender, an anti-malware company based in Bucharest, Romania. Most credit and debit cards issued in the United States store data on a magnetic stripe on the back.