You may have accidentally installed a browser extension or a small program that is "injecting" these popups into your browsing experience. How to Prevent Future Alerts
This is the "virus popup" scam, a classic piece of "scareware" designed to trick you into giving away your money or personal data. Here is how to handle these digital ambushes like a pro. What Exactly is a Virus Popup? virus popup
Press Option + Command + Esc , select your browser, and click Force Quit . You may have accidentally installed a browser extension
Go into your browser settings and clear your browsing history and cache to remove any lingering scripts. Why Am I Seeing These? select your browser