U.S. retail giant Target, whose stores were hit in a cyber attack in December, now says that the malicious software used for the theft of millions of credit card data was copying it from the company's sale registers.
Target Chairman and Chief Executive Officer, Gregg Steinhafel, said in a recent interview that officials detected the presence of malicious software on Sunday, December 15, and by six o'clock that evening, the company's system was safe and secure.
Before the malware was eliminated, though, between 70 and 110 million cards were compromised.
According to the Reuters News Agency, hackers gained access to the retailer's computer network, where they installed software that read the data from customers' credit cards as it was moving through the electronic payment process.
The data recorded on a card's magnetic strip is encrypted but, in order to authorize the transaction, the system must decipher it. The hackers' malware intervened in that process and stole the information.
Other popular U.S. retailers like Neiman Marcus, Barnes and Noble and Michael's also reported attacks at the point-of-sale terminals.