Good point! I have to believe that many of the "I got a virus on my Mac..." stories are pure fantasy or misunderstanding or (in rare cases) someone who's just trying to cause panic among Mac users. It's always "a friend" or "a friend of a friend" or very few details on exactly what happened.
Most of the time a new Mac user cries "Virus!", it's because something is happening they don't understand and they're unfamiliar with the differences between Windows and Mac OS X. If you read the dozens of threads in these forums with "virus" or "adware" or "trojan" or "malware" in the subject line, probably 90% of the time it's just someone who doesn't understand how to use their new Mac and they came from the Windows environment where viruses are rampant.
OK, I have been a mac user since the LC, programing computers for 25 years, and now develop for the mac, and own shares in the company. I'm no noob!
I was as amazed as you.
He has the latest version of leopard.
He almost definitely caught it downloading porn or from warez sites.
I think he might actually be infected by a second one that is causing native instruments Traktor to behave strange then every now and then cause a popup to buy anti virus software(he showed me this months ago, I put it down to coincidence and a software glitch and sent him on his way).
The one we encountered last night sends him to a domain such as 'googleadware.com' (i forget the exact name) after clicking on adwords in google. A search around the net revealed it was the iadware 'proof of concept'.
So yeah, how damn annoying, I dont want this crap to exist as much as the next person, but unfortunately it does exist.
I trashed a unix executable file in "internet plugins" called internet.prefs (or similar) and he told me he was cured but it could have been a fob off so he could go to bed as I had been trying to kill it for two hours.