Modus operandi: Harry the Hacker installs malware -- a type of software that damages or infiltrates a computer or network -- onto a legitimate website with low security. The malware instantly downloads onto your computer when you visit the site and allows Harry to access your information. In another scenario, Harry puts malware on public computers and gathers the information you share with that computer, says Urban. Harry also infiltrates the computer system of banks, retailers and other businesses and extracts personal account information, Noonan says.

Phishing Phil uses malware to go after your laptop. He sends emails with attachments that promise dancing kittens or some other bait. When the user opens the attachment, malware instantly downloads onto the computer and leaves confidential information vulnerable. Phil also sends emails from a familiar sender with a link to a contaminated website that installs malware onto your computer. Some malware, called spyware, allows Phil to capture every keystroke including passwords to your financial accounts.