Michaels Stores

Arts and crafts retailer Michaels Stores confirmed a breach of its payment systems in April that also included its subsidiary Aaron Brothers. The Irving, Texas-based comapany said investigators suspect that up to 3 million credit and debit cards may have been stolen. The attack took place between May 8, 2013 and Jan. 27, 2014, according to the retailer. The attackers targeted payment systems using memory scraping malware.

Two independent security firms conducted an assessment of the company's systems and determined that incident responders fully removed the malware and identified the full scope of the breach, the company said.