Trellix said it observed more than 450,000 infected machines in examining the marketplace. A specialized browser it offered customers made “account takeover child’s play for criminals,” their report says.

“While underground marketplaces that sell stolen credentials aren’t a new thing, Genesis Market was one of the first that focused on fingerprints and browser cookies to enable account takeovers despite growing MFA adoption,” the Trellix researchers said. The market, a “one-stop shop for account takeovers,” was advertised on several predominantly Russian-speaking underground forums, the cybersecurity firm Trellix, which assisted in the investigation, said in a research report. Criminal users of Genesis Market could purchase software scripts from it, including browser cookies and fingerprints that track a user's online activity.

“Cookie” refers to the web browser cookies that let people log onto websites without the need for multifactor authentication.

“Operation Cookie Monster,” the effort by law enforcement agencies in 17 countries, disrupted the largest marketplace of its kind, officials said.

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