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)