scareware
n.— «This Innovagest2000 domain has for at least four years now been associated with spyware and so-called “scareware,” surreptitiously installed software that bombards the victim with incessant and misleading warnings that their PC is infested with malicious software.» —“Following the Money: Rogue Anti-virus Software” by Brian Krebs Washington Post: Security Fix July 31, 2009. (source: Double-Tongued Dictionary)
Further reading
Katie in Everett, Washington, is curious about the expression If ifs and ands were pots and pans, there’d be no need for tinkers. What is a tinker? She heard this phrase on the television series The Gilded Age, in response to a character who...