The fashion retailer Forever 21 confirmed a breach involving unauthorized access to data from payment cards used at an undisclosed number of its stores due malfunctioning encryptions on POS devices.

The Los Angeles-based company said the probe focused on transactions made at its stores between March and October this year. Since the investigation continues, the company, which operates more than 815 stores in 57 countries, did not reveal the stores affected.

"With its endless POS endpoints, the retail industry has always been a desirable target for cybercriminals. They know that if they can introduce malware into POS networks, they can make a decent amount of cash by selling credit card numbers on the dark web," Mark Cline, a VP at Fort Lauderdale, Fla.-based Netsurion, a provider of managed security services for multi-location businesses, said. "With their millions of customers, large retailers, like Forever 21, have typically been the hardest hit. Companies must pay up to $172 per stolen record in clean-up costs. A major retailer just paid $18.5 million to address the impact of its 2013 hack, which resulted in 41 million stolen credit cards."