The vast majority of time viruses come from infected websites. These viruses exploit a security vulnerability in in your web browser, whether it’s Internet Explorer, Firefox, or another. The owner of the website from which your computer contracted the virus may or may not be aware that it contains malicious code. It’s been estimate that over 90% of the infected websites on the World Wide Web are legitimate, meaning that the people who own or manage the website are not aware that their website is infected and were not the ones who infected it in the first place. To give an example, a while back we had four different customers who came to us with infected computers who swore that the last website they visited was that of a major airline. This was too coincidental not to be true.

Your best protection against these threats is to be careful what websites you visit, what links you click on, and keep your antivirus software up to date.