Cybercriminals are redoubling efforts to steal payment card details from retailers before new defenses are put in place. More than a dozen types of malware were found last year that target point-of-sale systems. Major retailers affected by card breaches in the last few years, including Target, have upgraded their systems. But the cost and long delays in getting new systems certified have delayed the transition, leaving a window for cybercriminals to steal card details to sell on the black market. In response, card issuers and banks have improved their ability to block potentially fraudulent transactions.”]