These so-called rogue antivirus products can sometimes lower security settings on a victim's computer. At best, they offer a false sense of security because the products never protect computers from the latest security threats.

Rogue antivirus has been a major headache for users over the past year. It is often installed via annoying pop-up ads that try to convince the victim that something is wrong with their PC. Symantec tracked 43 million rogue AV installation attempts between July 2008 and July 2009.