Malware planted on Home Depot's payment-processing system compromised up to 56 million credit and debit payment cards used in self-checkout lanes at U.S. and Canadian stores between April and September of 2014. Fraudsters also stole separate files containing 53 million email addresses. Home Depot said in an earlier filing that the fraudsters used a vendor's user name and password "to enter the perimeter of the company's network" and eventually plant the malware.