Mac Musings

A Few Good Reasons to Have Antivirus Software on Your Mac

Daniel Knight - 2005.04.07

There are two camps when it comes to antivirus software for the Mac - "better safe than sorry" and "wake me up if it ever happens."

Under the classic Mac OS, there was a grand total of 68 viruses. For Mac OS X, not a single one in four years on the market.

That's not to say that Macs are impervious to viruses, only that not one single insidious virus creator has managed to create and release a Mac OS X virus thus far. Whether that's because none of them are trying (unlikely) or that the Mac is much harder to hack (my vote), we're safe so far.

Typhoid Mary and Virus Mac

Since there are no OS X viruses yet, I haven't recommended buying antivirus software. Until a virus exists, it's only going to expend CPU cycles and find Windows viruses attached to your email. It can't protect the Mac OS from something that doesn't yet exist.

But there are arguments in favor of antivirus software on the Mac. Someday someone somewhere will probably create and release an OS X virus. When that happens, if you have antivirus software that's set to scan your computer daily and check for updated virus definitions daily, you'll be well protected.

A second argument in favor of running antivirus software on your Mac is Windows. Whether you use it (Virtual PC), someone using Windows accesses files on your Mac, or you run a mail server under OS X, there's always the danger of spreading a Windows virus to a Windows user.

This is the "Typhoid Mary" argument - Macs can't be infected, but they can be virus carriers.

In my opinion that's just one more argument for going Mac, but in the real world there are a lot of Windows users out there, and some consider it poor netiquette not to clear Windows viruses from your Mac.

Don't Waste Your Money

There are several free antivirus and anti-spyware programs for Windows computers. (Beware - a lot of them masquerade as useful software while installing malware. Only install wares recommended by reputable sources.)

And now there's a free antivirus programs for Macs. It's called clamXav, a Mac interface for the Unix clamav program. H Wayne Anderson recommended it after reading Symantec's Self-Serving Ravings Spread Fear, Uncertainty, Doubt about OS X Security. He recommends it primarily because he believes Macs should be good network and Internet citizens, which means not allowing your Mac to spread Windows malware.

I can't fault his logic. If your Mac exists on a mixed network, might be accessed from a Windows PC over the Internet, or runs Virtual PC, you owe it to yourself and everyone who may connect to your computer to run a clean machine.

Imagine the bad PR Macs would get if it was discovered that they were somehow being used to spread Windows viruses. We'd become pariahs, the Typhoid Mary's of the Internet and workplace. The already-low Mac market share would plummet, perhaps resulting in the death of the platform.

iPods and Flash Drives

One more reason to become socially responsible is shared drives. What if you use your iPod or USB flash drive on a Windows PC, pick up a virus, and then transfer that virus to the next Windows PC you connect it to? You don't even have to be on a network for a "sneakernet" virus to spread, and having antivirus software on your Mac would let you scan the iPod or flash drive before you use it on another Window PC.

How Macs Will Become Infected

Anderson contends that learned behavior is the most likely way for malware to make its way onto the Mac. A lot of Windows malware comes packaged with a nifty utility program, a menu bar for Internet Explorer, a hack that changes the Windows cursor, etc. People run the installers, get the neat program, and don't realize that they've just infected their PCs.

The same could happen on the Mac, and it's more likely to happen that way than via email or visiting a Web page. You'll hear about a great new freeware program, install it, enter your password when it asks (c'mon, you know you would), get your utility, and find your Mac infected with some type of virus, spyware program, or mail robot that spammers can use to hijack your computer.

With antivirus software on your Mac set to run during your lunch break, after you leave the office for the day, before you get to work, or at some other time when it won't greatly inconvenience you, you'll know pretty quickly if you've been infected.

I'm running clamXav right now. First on my iPod, then on my user folder. Next, my Downloads folder, and then my Applications.

It's not an especially fast program, but you can run it in the background. And you can set the Preferences so it will check for updates to the program or the virus definitions each time it's launched. You can set it to run one day a week or every day, on any day you choose, and at a time of day that's convenient for you.

I honestly don't expect to find any viruses on my eMac, mostly because I get rid of my junk mail in a hurry. And even if I did find something, I know it's not going to infect anyone - the lone Windows PC isn't ever logged into the eMac.

I still think it's the primary responsibility of Windows users to maker sure their systems are secure - and that until an OS X virus exists, Mac antivirus software won't do a thing to protect our Apple computers. But the fact remains that we live in a connected world, so the only responsible thing to do if your Mac interacts with Windows PCs is make sure it doesn't turn into "Virus Mac".

Thanks to clamXav, you can even do it for free.