“When people think about security, they are thinking about the really big super-computers, firewalls, a lot of security systems,” said Yoohwan Kim, a computer science professor at the University of Nevada, Las Vegas, whose expertise includes network security. The security attacks that triggered an FBI probe shatter a public perception that casino security requires an “Oceans 11”-level effort to defeat it. The casino giant said its casino and hotel computer operations weren’t disrupted but couldn’t say with certainty that personal information about tens of millions of its customers was secure following the data breach.

By Thursday, Caesars Entertainment - the largest casino owner in the world - confirmed it, too, had been hit by a cybersecurity attack.