A warning message that pops up from a website that claims the user's computer is currently contaminated or not running properly. Also called "fake antivirus" and "rogue antivirus," scareware is a dishonest attempt to cause a user to purchase antivirus, registry cleaner or some other software that repairs problems or enhances performance.
Worse yet, scareware may be used to entice the user to install phony software that implants a real virus or some other malware. In either case, the dire warning frightens people into taking action. See ransomware