Four people have been arrested and more than 100 internet servers taken down or disrupted in an internationally coordinated operation targeting the cyber infrastructure used for malware, Europol said on Thursday.
Carried out between May 27 and 29, the European Union's law enforcement agency called it "the largest ever operation against botnets, which play a major role in the deployment of ransomware".
Dismantled botnets included botnets IcedID, Smokeloader, SystemBC, Pikabot and Bumblebee, it added.
The sting, dubbed Operation Endgame, was initiated and led by France, Germany and the Netherlands. It involved several other countries, including Britain, the United States and Ukraine, Europol said in a statement.
"With the largest international cyber police operation to date, law enforcement authorities have dealt a significant blow to the cybercrime scene," Martina Link, vice president of Germany's federal criminal police office, said in a separate statement.
The arrests were made in Armenia and Ukraine, it said, adding that more than 2,000 domains were now under the control of law enforcement.
Malware allows cybercriminals to secretly connect to peoples' computers for malicious purposes.
One of the main suspects earned at least 69 million euros ($74.5 million) in cryptocurrency by renting out criminal infrastructure sites to deploy ransomware, according to investigators.
