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Computerworld - You'd think it was the end of the world.

The fact that Mac users have fallen victim to "scareware" scams -- the kind that have long plagued Windows users -- shouldn't come as a surprise. After all, fake antivirus software schemes like MacDefender don't have to rely on exploitable vulnerabilities, but instead typically depend on tricking users into visiting malicious sites and duping them into installing the software.

And Mac users, for all their pretensions otherwise, are as fallible as the next person.

But from the news accounts this month about MacDefender, and the posts not only on Mac-specific blogs but also on ones usually devoted to Windows, you could be forgiven for thinking that Macs are suddenly the victims of choice.

They're not. Windows machines remain the most common target because, well, globally Windows PCs outnumber Mac OS by more than 16-to-1.

What is true is that Mac users now face the same scareware scams that Windows owners have had to deal with for years.

So what's the deal? Macpocalypse or not? And what should you watch for, and what can you do to keep safe?

Those are the questions we try to answer.

Is MacDefender a worm? Nope. Although MacDefender and its ilk fall under the general term "malware" -- as in, it's malicious in some way -- it's not a virus, not a worm, not a true Trojan horse.

Instead, its one of a long line of "scareware" or "rogueware," terms that apply to fake -- hence "rogue" -- software that tries to spook you -- that's the "scare" -- into paying for a worthless program.

The labels are usually slapped on phony security software that claims a computer is heavily infected with worms, viruses and other malware. Such software nags users with pervasive pop-ups and fake alerts until they fork over the "registration" fee, which in MacDefender's case ranges between $60 and $80.

The criminals monetize their work by collecting these fees. And it's a profitable trade, at least where Windows scareware's concerned. Back in 2008, SecureWorks, now owned by Dell, said that some bad guys were making as much as $5 million a year shilling scareware.

So MacDefender isn't hacking my Mac? No. Although scareware targeting Windows has been known to silently plant itself on PCs after other malware first exploits a security vulnerability in the OS or other software, MacDefender doesn't.

That's a possible future move, of course, assuming attackers spend the time digging up an unpatched vulnerability in, say, Mac OS X or a browser like Safari or Firefox, and then write an exploit.

So how do Macs get infected with things like MacDefender? Easy, they dupe users into doing the job for them.