Trend Micro said in a month it had identified 990 compromised websites which had a malicious script that diverted a visitor to a second site related to the tech support scam. The campaign began in January.
The addition of the cryptocurrency miner was a recent twist. "Of late, though, the campaign has added the Coinhive JS miner into ongoing attacks, turning the victim’s computer into a monero cryptocurrency miner," the researchers said.
Country distribution of EITest’s tech support scam.
Most of the victims have been in Japan but a small number have been affected in Australia as well.
On visiting a compromised website, the browser being used if identified. Then a phishing script is injected directly into the web page if the user’s browser is Chrome. Initial tests show that Firefox is not affected.
"The phishing script is coded to notify the user to download the Hoefler Text font to properly display the page, but it actually downloads a malicious executable file," the researchers said.
"EITest takes this up a notch: If the user’s browser is Internet Explorer, he/she is redirected to a tech support phishing page containing the Coinhive monero-mining JS script."
Screenshot of the tech support scam web page.
The website hosting the tech support scam masquerades as a legitimate Windows notification, alerting victims that the system has been infected with malware.
"It will prod the user to call their 'technical department' to resolve the issue," Trend Micro said. "Behind the scenes, however, the web page will load script from Coinhive’s server and launch a JS cryptocurrency miner. Users won’t notice that their system has been affected apart from system lags or performance issues."
But there was a simple way to stop the miner from running: one could just close the web page as the script in question had no persistence mechanism.
Graphics: courtesy Trend Micro