Cyber criminals have struck again, only this time, they've decided to go through the gut: Domino's Pizza. Hackers in Europe made off with more than 650,000 customer accounts Friday and threatened to release the data if their demands were not met.

Hacker group Rex Mundi demanded that Domino's Pizza pay 30,000 euros, or $40,800, by 8 p.m. CET Monday. If not, Rex Mundi said it would release all of the information on the Internet. The Domino's locations affected are in France and Belgium.

Rex Mundi wrote the following ransom letter Friday:

"Earlier this week, we hacked our way into the servers of Domino's Pizza France and Belgium, who happen to share the same vulnerable database. And boy, did we find some juicy stuff in there! We downloaded over 592,000 customer records (including passwords) from French customers and over 58,000 records from Belgian ones. That's over 600,000 records, which include the customers' full names, addresses, phone numbers, email addresses, passwords and delivery instructions. (Oh, and their favorite pizza topping as well because why not)."

Domino's has stated that it will not be paying the ransom, and at the time of this report, past 8 p.m. CET, there is no sign of a payment by Domino's or the stolen information appearing online.

"There are clear indications that something is broken on our server. The information contained in them is protected," Domino's Pizza chief executive Andre ten Wold told Dutch news outlet De Standaard. "Financial data, such as credit cards, has not been stolen."

While the threat might not be immediately financial, many people use the same passwords for many accounts, making the information from the Domino's breach sensitive.

Rex Mundi has a history of exploiting companies for financial gain. The group broke into hosting firm Alfa Hosting and posted the information of 12,000 customers this year and, in 2012, posted loan applicant information from AmeriCash advance on the Internet.

In other Domino's news, the pizza chain added a Siri-like feature to its mobile app Monday. Dubbed "Dom," the app is touted to bring a "human-like, conversational" experience to ordering pizza via the company's iPhone or Android app.

"It is not perfect," Domino's CEO Patrick Doyle said in an interview. "This is the sort of thing, like any other really new technology launch, you're going to learn, you're going to get better."

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