Do Macs need antivirus software?

Macs don't get viruses. You'll hear the phrase repeated over and over again from all corners of the Web, well-meaning Mac-using friends, and even Apple itself; the impervious nature of Macintosh computers is practically common knowledge by now. But what if that common knowledge is wrong? The past year saw several high-profile Mac attacks make headlines. As Mac sales skyrocket and Apple computers lose their "security through obscurity," it's time to reexamine the issue: do Macs need antivirus software?

Macs ARE built more securely than Windows PCs

There's no denying that Macs are a tough nut to crack. They include several security-minded features you won't find on Windows PCs: built-in antivirus and anti-phishing technology, sandboxing features that limit what stand-alone programs can do to your computer, encryption for your hard drive, administrative passwords and much more. Sounds great, right?

But ...

Despite all those protections, malware still manages to find its way into Macintosh computers, highlighted by the May 2011 "MacDefender" scare. MacDefender, a variant of the well-known "adware" or "scareware" type of attack, used pop-ups and infection warnings to try and trick users into buying fake antivirus software. According to reports from ArsTechnica.com and ZDNet.com, the malware was fairly widespread and responsible for large spikes in help requests at Apple stores and the AppleCare call center.

The way Apple handled the outbreak highlights another problem with putting all of your security eggs into the Apple basket; although the company eventually released documents and updates that helped squash the scareware, ZDNet.com reports that Apple initially told its call center reps to avoid helping users remove MacDefender in any way. In fact, the reps couldn't even direct callers to online discussions about the topic. On the other hand, MacDefender's existence was first reported by Intego, which offers antivirus and security software for Macs.

How common is Mac malware?

Security company F-Secure's recently released 2011 Mac malware summary claims that 58 new Apple-specific threats reared their ugly heads between April and December. "That's nothing when compared to Windows malware -- but it's definitely something when compared to the number of Mac threats seen prior to 2011," the research team writes. And it's true: in a 2010 security summary, Intego reported that no major Mac viruses had been found "in the wild" that year.

By comparison, G Data reports that over 1,000,000 new Windows-focused malware threats are discovered each year. Don't let that number fool you, though: ZDNet.com's Ed Bott did some digging and discovered that only about 1 percent of Windows computers worldwide are infected with malware.

So do Macs need additional malware protection?

Experts say you should install Mac-specific antivirus software -- and at one point, Apple agreed -- but they suggest that most users will be fine with free programs given Macs' strong inherent security and lower threat level. If you want extra security features and don't mind paying for the privilege, most companies that offer Windows security software also offer Mac versions, while Intego is a well-regarded security software firm that focuses solely on Apple computers. And if you run Windows on your Mac, you'll need to install Windows security software to ward off those widespread Windows-targeted infections.

For more info about specific Mac security options -- including free programs -- read our recently updated reports on antivirus software and Internet security software.