Your uncle’s frozen Mac says it’s infected after viewing a Google ad. Now what?

Researchers say they recently found Google ads delivering a sophisticated tech support scam that freezes the screens of both Windows and Mac devices and displays messages urgently instructing them to phone a bogus call center. The ads were displayed all over the web, including on high-traffic maps, weather, real-estate, document-hosting, and sports sites. Users who called the number were then urged to pay hefty fees, grant remote access to their devices, or divulge personal information.