Over 500,000 credit card numbers in Australia were discovered compromised today, stolen through a hack on a business’ point of sale system.

Law enforcement suspects a group of Romanian hackers is behind the attack.

According to SC Magazine, law enforcement was alerted to the scheme when banks started noticing fraudulent activity on the credit cards. It is expected that the 500,000 credit cards will be sold on the black market. The banks have already shut down access to those credit card numbers.

The hack was allegedly executed by the same Romanian hacker ring that stole credit card information from point of sale terminals in Subway restaurants across the United States. Reports say the hackers were able to access the point of sale systems using Microsoft Remote Desktop Protocol, which was left open and unprotected so that the company could “monitor stocks.” From there they installed a program to grab credit card information when a card is swiped.

Australian law enforcement has otherwise not disclosed the name of the business due to the ongoing investigation.

In March, a similar hack occurred on Global Payments’ point of sale system. Over 1.5 million credit card numbers were stolen from systems installed in New York City parking garages. The attack was uncovered when Visa and Mastercard suddenly began warning banks about a large number of compromised credit cards. By the time the story surfaced in April, law enforcement said the issue was “contained.”

hat tip Wired, via SC Magazine; Photoshop via Meghan Kelly, Australian Flag and POS images via Shutterstock