According to a recent article posted by Stu Sjouwerman over on the KnowBe4 blog, nine out of ten malware infection now originate from legitimate web sites that have been compromised. That means your system can be infected by visiting sites of major companies that you trust. Ouch!
Read more here:
http://blog.knowbe4.com/bid/311054/Avoiding-Dodgy-Web-Sites-No-Longer-Works-To-Stay-Safe