On suspicion of running deer.io, a massive platform for buying and selling stolen account credentials for thousands of popular online services and shops, FBI officials arrested a Russian computer security researcher last week.

Kirill V. Firsov was arrested on Mar. 7 following his arrival at
John F. Kennedy Airport in New York, unsealed Monday according to court documents. Prosecutors and U.S. District Court for California’s Southern District claimed Firsov was the administrator of deer.io, an online platform that housed more than 24,000 stolen and/or compromised usernames and passwords for a number of top online destinations to sell.

“From on or about a date unknown through March 4, 2020, in the Southern District of California and elsewhere, defendant Kirill Victorovich Firsov, without the authorization of the issuer of access devices belonging to customers of Company A, to wit account Names and passwords used to obtain money, goods, services or any other thing of value, knowingly and with intent to defraud, did aid and abet soliciting buyers through the DEER.IO platform with the purpose of offering and selling information regarding said access devices,” the criminal complaint said.

Deer.io as a Russian-based web marketplace that ‘ allows criminals to purchase on – the-platform access to cyber storefronts to market their illegal products or services. ‘ The online platform has been operating since at least October 2013 and gained more than $17 million in sales as of early March, the court document said.