The hack has affected 700 computer systems at Micros and is thought to have begun with infiltration on a single machine at the company, said Brian Krebs on his Krebs on Security blog on Monday.
The incident is worrying for the potential size of the hack and the systems affected. Oracle acquired Micros in 2014, when it said Micros systems are used in more than 330,000 sites in 180 countries.
