A researcher has documented almost 2,500 sites that are actively running cryptocurrency mining code in the browsers of unsuspecting visitors, a finding that suggests the unethical and possibly illegal practice has only picked up steam since it came to light a few weeks ago.
Willem de Groot, an independent security researcher who reported the findings Tuesday, told Ars that he believes all of the 2,496 sites he tracked are running out-of-date software with known security vulnerabilities that have been exploited to give attackers control. Attackers, he said, then used their access to add code that surreptitiously harnesses the CPUs and electricity of visitors to generate the digital currency known as Monero. About 80 percent of those sites, he added, also contain other types of malware that can steal visitors' payment card details.
"Apparently, cyberthieves are squeezing every penny out of their confiscated assets," he said.