Google Online Security Blog: The Rise of Fake Anti-Virus

One increasingly prevalent threat is the spread of Fake Anti-Virus (Fake AV) products. This malicious software takes advantage of users.One increasingly prevalent threat is the spread of Fake Anti-Virus (Fake AV) products. This malicious software takes advantage of users’ fear that their computer is vulnerable, as well as their desire to take the proper corrective action. Visiting a malicious or compromised web site — or sometimes even viewing a malicious ad — can produce a screen looking something like the following:

For example, a recent Symantec report showed a 71% increase in malicious software and also noted a rise in fake anti virus problems. Google Researchers have warned of this high rise of fake antivirus software, which can trick users into paying for a useless software suite. Fake anti-virus attacks spread easily without requiring any vulnerability on a victim's computer system. Using data from 2009 the team saw a rise in fake anti-virus software from three per cent of infected domains to 15 per cent. In January 2009 there were 93 domains hosting fake anti-virus software but by the end of the year this had risen to 587.
Google Online Security Blog: The Rise of Fake Anti-Virus