(Reuters) – International law enforcement agencies said on Wednesday they had dismantled a criminal hacking scheme used to steal billions of dollars from businesses and private citizens worldwide.

Police in six European countries, as well as Canada and the United States, completed a joint operation to take control of Internet servers used to run and control a malware network known as “Emotet,” authorities said in a statement.

“Emotet is currently seen as the most dangerous malware globally,” Germany’s BKA federal police agency said in a statement. “The smashing of the Emotet infrastructure is a significant blow against international organized Internet crime.”

Emotet is used by cyber criminals to first gain access to a victim’s computer before then downloading additional malicious software, such as trojans designed to steal banking passwords or ransomware which can lock a computer until an extortion fee is paid.

Security experts say Emotet’s operators often sell access to victims’ computers to other hackers, using a “malware-as-a-service” business model that has made them one of the world’s most prolific and damaging cybercrime groups.

German police said infections with Emotet had caused at least 14.5 million euros ($17.56 million) of damage in their country. Globally, Emotet-linked damages cost about $2.5 billion, Ukrainian authorities said.

Ukraine’s General Prosecutor said police had carried out raids in the eastern city of Kharkiv to seize computers used by the hackers. Authorities released photos showing piles of bank cards, cash and a room festooned with tangled computer equipment, but did not say if any arrests were made.

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(Reporting by Zuzanna Szymanska in Gdansk, Pavel Polityuk in Kyiv and Jack Stubbs in London; Writing by Jack Stubbs; Editing by Bernadette Baum)