Two Romanian men have admitted to participating in an international conspiracy that hacked into credit-card payment terminals at more than 150 Subway restaurant franchises and stole data for more than 146,000 accounts. The heist, which spanned the years 2009 to 2011, racked up more than $10 million in losses, federal prosecutors said.

Iulian Dolan, 28, of Craiova, Romania, pleaded guilty to one count of conspiracy to commit computer fraud and two counts of conspiracy to commit credit card fraud, documents filed on Monday in US District Court in New Hampshire showed. Dolan admitted he helped alleged ring leader Adrian-Tiberiu Oprea scan the Internet for point-of-sale systems. "These were typically password-protected, so Dolan would attempt to crack the passwords, where necessary," Monday's plea agreement, which was signed by the defendant, stated. "Next, once he cracked the password and gained administrative access, Dolan remotely installed software programs called 'keystroke loggers' (or 'sniffers') onto the POS systems. These programs would record, and then store, all of the data that was keyed into or swiped through the merchants' POS systems, including customers' payment card data."

Dolan hacked into "several hundred US merchants'" systems and stole payment data belonging to about 6,000 cardholders, according to the document. He has agreed to spend seven years in prison. Ars reported on the online heist last last year.

Cezar Iulian Butu, 27, of Ploiesti, Romania, pleaded guilty to one count of conspiracy to commit credit card fraud. In a separate plea agreement that was also signed, he admitted repeatedly asking Oprea to provide him with payment card data stolen through the conspiracy. He obtained data belonging to about 140 cardholders. Butu has agreed to be sentenced to 21 months in prison.

Oprea remains in US custody and is awaiting trial in the District of New Hampshire.

This article was updated to correct the misspelling of Oprea's name.