Microsoft has recently stated that it saved millions of computers from being victimized by one the world’s biggest cybercrime rings earlier this month. The company confirmed that a virus had infected 2 million PCs, and used to steal $500 million from bank accounts across the world. The Citadel Botnets targeted firms varying from tiny credit unions to big global banks such as BOA, HSBC, Credit Suisse and the Royal Bank of Canada.

“We definitely have liberated at least 2 million PCs globally. That is a conservative estimate,” Richard Domingues Boscovich, assistant general counsel with Microsoft’s Digital Crimes Unit, said in an interview on Tuesday.

“We feel confident that we really got most of the ones that we were after,” he said. “It was a very, very successful disruptive action.” He also said that the vast majority of the machines were infected in the United States, Hong Kong and Europe.

Microsoft had worked with the FBI, supported by authorities from more than 80 countries across the globe. The attack was stopped on June 5 by removing the access from 1,400 malicious computer networks known as the Citadel Botnets. Microsoft’s Digital Crimes Unit in collaboration with its partners is still working to find how many of these Citadel botnets are still functioning. The citadels ringleader, known as Aquabox as well as dozens of botnet operators are still at large and the company is working on uncovering their identities.