United States authorities say an international law enforcement operation has taken down the notorious "Qakbot" malware platform used extensively by cybercriminals in a variety of financial crimes.
First discovered more than a decade ago, Qakbot is commonly spread through malicious, boobytrapped emails sent to unsuspecting victims.
The US Department of Justice said the operation, nicknamed Duck Hunt, involved the Federal Bureau of Investigation as well as France, Germany, the Netherlands, the United Kingdom, Romania and Latvia.
US attorney Martin Estrada said the move against Qakbot was the most significant technological and financial operation ever led by the department against a botnet.
The term botnet is used to refer to an interconnected network of infected computers that hackers use to spread viruses.
"Together we have taken down Qakbot and saved countless victims from future attacks," he told a news conference.
Security researchers say they believe Qakbot originates from Russia and has attacked organisations around the world, from Germany to Argentina.
Estrada said Qakbot malware had infected more than 700,000 victim computers, facilitated ransomware deployments and caused hundreds of millions of dollars in damage to businesses, healthcare providers and government agencies.
As part of the operation, agencies seized 52 servers in the United States and abroad.
Investigators found evidence that between October 2021 and April 2023, Qakbot administrators received fees corresponding to approximately $US58 million ($A89 million) in ransoms paid by victims.
In order to cripple the cybercrime network, the FBI said it had redirected Qakbot internet traffic to bureau-controlled servers that effectively uninstalled the corresponding malware from victim computers.
In doing so, the FBI said it had actively removed malicious files from private systems while not viewing or collecting any personal information.
In a statement, FBI director Christopher Wray said victims ranged from financial institutions on the US east coast to a critical infrastructure government contractor in the midwest to a medical device manufacturer on the west coast.
"The FBI neutralised this far-reaching criminal supply chain, cutting it off at the knees," he said.
have announced an international law enforcement operation to disrupt the notorious "Qakbot" malware platform used extensively used by cybercriminals involved in financial crime.
"Qakbot malware infected more than 700,000 victim computers, facilitated ransomware deployments and caused hundreds of millions of dollars in damage to businesses, healthcare providers, and government agencies all over the world," the US Department of Justice said in a statement.