scareware
n.— «Researchers are also warning of new forms of scareware that are coming up on paid search results. Scareware is a term for fake antivirus software sites that appear to come from well-known vendors such as Microsoft.» —“Spammers Are Gaming Google’s Adwords” by Richard Adhikari InternetNews Jan. 22, 2009. (source: Double-Tongued Dictionary)