CNN has reported that a group of Nigerian hackers is trying to scam the biggest companies around the world off of billions of dollars.

The group, their name identified as “London Blue,” after an investigation by cybersecurity firm Agari, another company attacked by the group, are said to be sending emails that mainly targets the chief financial officers (CFO) of these companies.

The businesses targeted range from small businesses to the largest multinational corporations, more than half of them in the US.

FBI estimates that between October 2013 and May 2018, $12 billion has been lost to this kind of scam.

More than 50,000 finance executives have been targeted by London Blue, the group said to be large and carrying out its scam in several languages and with at least 17 collaborators in the United States, United Kingdom and other parts of Europe.

The group of Nigerian hackers “operates like a modern corporation,” with people working on business intelligence, sales, email marketing, financial operations, and human resources.