The FBI has discovered about 20 cyberattacks against retailers in the past year similar to the one against Target and has warned companies to prepare for more attempts to breach their systems.
The attack on Target used "memory-parsing" malware that infects point-of-sale (POS) systems such as cash registers and credit-card swiping machines to steal information from tens of millions of cards.
"The accessibility of the malware on underground forums, the affordability of the software and the huge potential profits to be made from retail POS systems in the United States make this type of financially motivated cyber crime attractive to a wide range of actors," the FBI said.
"Everybody we work with in the retail space is scared to death," says a cyber-security consultant. "They don't have a lot of defenses to prepare against these types of attacks."