By day I work in IT Security and see many "Drive By" attacks (visit a legitimate website that is infected) with attacks workstations with vulnerable software using Windows leading to the download and installation of Trojans and Fake AV etc all without user intervention.

But recently this has been happening to Macs due to Apple lagging behind with the Java 6 Update 31 distribution to machines prior to Lion where they controlled Java this has lead to the same "Drive By" attacks installing Backdoors on Mac OSX.

Apple have released the patched version, so if you use your Mac to browse as well as edit, update your Java (if installed) and run a free virus scan on the machine.

More details here.

http://www.bbc.co.uk/news/science-environment-17623422

Dean

A page to check if your Mac is infected https://www.drweb.com/flashback/

Apparently Apple are working on a tool to remove any infections found as well as removing the command and control network http://support.apple.com/kb/HT5244

Dean