Malicious attacks are part of doing business online. But a new report released by Symantec warns that hackers are no longer content to use email attachments. Instead, a new breed of cyber criminals are exploiting security holes in search engines, social networks and browsers. According to Symantec, the threat could undercut user confidence in the entire internet, including many trusted websites.

In 2006, Symantec found 125,243 threats that used holes in legitimate websites to trap unsuspecting users. That number mushroomed to 711,912 for 2007.

One such attack takes advantage of a weakness in Google's search engine. According to Symantec, a Google search for some terms redirects users to what appears to be a bona fide site. Instead, the site infects users' computers with malware. Google said it is working to fix the problem. 

"Rather than set a bear trap -- a porn or get-rich-quick site loaded with malicious code -- to entice users, hackers are actively hunting by injecting their bad stuff on trustworthy sites," Billy Hoffman, manager of Hewlett-Packard Security Labs, told USA Today.

The new wave of attacks are also focused on social networks like Facebook, MySpace and Orkut. According to Symantec, hackers are taking advantage of open developer platforms to load malicious widgets and other applications into the social networks.

Earlier this year, security firm Fortinet discovered a malicious widget on Facebook that attempted to lure users by revealing who had a secret crush on them. That widget was neutralized, but the sheer number of new widgets launched on Facebook means the threat remains high.

Perhaps more alarming, officials at Symantec believe the number of "compromised" sites is slowly outpacing the number of malicious sites created specifically by the criminals.