The seizure of the website was carried out by authorities in Bulgaria acting in co-ordination with the FBI, a statement from the US Department of Justice said.
Named as Sebastien Vachon-Desjardins of Gatineau, the man was charged in Florida over having allegedly obtained st least US$27.6 million (A$36 million) by using the NetWalker ransomware to extort companies.
About US$454,530 in cryptocurrency was seized on 10 January, the statement said, adding that this allegedly was paid by three victims of the ransomware.
The NetWalker site on the dark web now has an image saying it has been seized.
“Ransomware victims should know that coming forward to law enforcement as soon as possible after an attack can lead to significant results like those achieved in today’s multi-faceted operation.”
US Attorney Maria Chapa Lopez for the Middle District of Florida said: “This action reflects the resolve of the US Attorney’s Office for the Middle District of Florida to target and disrupt sophisticated, international cyber crime schemes.
“While these individuals believe they operate anonymously in the digital space, we have the skill and tenacity to identify and prosecute these actors to the full extent of the law and seize their criminal proceeds.”