Antivirus firm Intego today noted the discovery of new malware known as "MACDefender" targeting Mac OS X users via Safari.



From MacRumors:

When a user clicks on a link after performing a search on a search engine such as Google, this takes them to a web site whose page contains JavaScript that automatically downloads a file. In this case, the file downloaded is a compressed ZIP archive, which, if a specific option in a web browser is checked (Open "safe" files after downloading in Safari, for example), will open.

  New 'MACDefender' Malware Threat for Mac OS X