So I'd be safe in assuming that this malware isn't something new then, just a variation of something that has been before, if it's been blacklisted?

I'm worried that it's still on my machine. It's the annoying thing with OS X, at least with windows you know where you stand ( if you know how to look for malware on a machine). Two scans have given me the all clear.

How is this going to be prevented?