About $75 million has been stolen from bank accounts in a massive cyber bank heist after fraudsters raided dozens of financial institutions around the world.

According to a joint report by software security firm McAfee and Guardian Analytics, more than 60 firms have suffered from what it has called an “insider level of understanding.”

“The fraudsters’ objective in these attacks is to siphon large amounts from high balance accounts, hence the name chosen for this research — Operation High Roller,” the report said.

“The total attempted fraud could be as high as $2.5 billion,” it added.

The automated malicious software program was discovered to have used servers to process thousands of attempted thefts from both commercial firms and private individuals.