The breach has now definitely been confirmed, and the impact is huge: approximately 3 million payment cards were potentially compromised.
Since the January announcement, Michaels has retained two independent security firms to investigate the breach and has worked closely with law enforcement authorities.
"After weeks of analysis, the company discovered evidence confirming that systems of Michaels stores in the United States and its subsidiary, Aaron Brothers, were attacked by criminals using highly sophisticated malware that had not been encountered previously by either of the security firms," the company stated in the press release.
The affected systems contained payment card numbers and expiration dates, but it seems that the customers' name, address or PIN weren't compromised.
"Regarding Michaels stores, the attack targeted a limited portion of the point-of-sale systems at a varying number of stores between May 8, 2013 and January 27, 2014. The analysis conducted by the security firms and the company shows that approximately 2.6 million cards may have been impacted, which represents about 7% of payment cards used at Michaels stores in the US during the relevant time period," they stated, and offered a list of stores that were affected.
A similar list has been compiled of the Aaron Brothers stores affected by the malware between 26, 2013 and February 27, 2014, when some 400,000 cards are thought to have been impacted.
"The company has provided data about potentially affected payment cards to the relevant card brands so they can take appropriate action," the press release says. "While the company has received limited reports of fraud, it is offering identity protection, credit monitoring and fraud assistance services to affected Michaels and Aaron Brothers customers in the U.S. for 12 months at no cost to them."