While it's relatively unlikely you'll run into malware using the Mac, it's not impossible, and you may want to consider an antivirus tool to protect your Windows-using friends from any malware you might inadvertently send their way. We think that Sophos Anti-Virus for Mac is the best choice, and it's free.
Note: We've changed our previous app directory recommendation of nothing at all to reflect the growing pool of Mac malware. Even the safest browsing habits don't protect you completely. Sophos has an excellent breakdown of the history of malware for the Mac going all the way back to 1982. The fact that the article exists should remind Mac users that while they're not the primary target for malware authors (owing to the smaller base of Mac users), they're by no means invulnerable.
Platform: Mac OS X (10.4+) Price: Free
- Compact, easy-to-use interface that can be used for custom on-demand scans of files, folders and drives, or scheduled, periodic full scans of your Mac.
- Also scans files on your Mac for known Windows malware, trojans and viruses, and deletes or quarantines them so you don't risk spreading them to someone else via network share, USB drive or email.
- Deletes or quarantines known threats, gives you the option to quarantine anything suspicious that may be a new threat or dangerous file.
- Runs quietly in the background, scanning emails, downloads and any other files on access, stopping you from opening them before they can do any harm.
- Light on system resources while running in the background.
- Installs like any other Mac application and uninstalls just as easily -- no complicated packages or components to manage or configure.
- Sophos' "Live Antivirus" feature updates your app the moment new threats are detected or found in the wild. The feature also performs real-time lookups to see if files accessed are in the SophosLabs database, even if they're unfamiliar to the app.
- Supports OS X up to 10.8 and back to 10.4, and is completely free for all versions.
Where It Excels
Sophos Anti-Virus for Mac stands out in a somewhat crowded field of Mac antivirus apps because it doesn't just scan your Mac's files and folders on demand, but it does it quietly in the background without tapping your already precious system resources in the process. The utility also keeps its own constantly updating database of Windows viruses, trojans and other threats, so if you inadvertently download a Windows virus or trojan that won't harm you, you don't run the risk of sending it off to someone else by forwarding the message, or you won't infect other computers on your network via shared drives. Sophos is smart enough to tell you "Hey, this won't hurt you, but we're going to quarantine/delete it so you don't accidentally email this attachment to someone else." That's a huge benefit -- and it keeps you from being that guy no one likes.
Another banner feature Sophos offers that its competition doesn't is its live, real-time access to SophosLabs. "Live Antivirus", as it's called in the app, gives you an added layer of protection. The app automatically identifies and quarantines suspicious files, installers and other packages that may not be well known threats yet but definitely exhibit behaviour suspicious enough that Sophos is looking into them.
Best of all though, in our testing, Sophos was one of the most resource-light antivirus apps on the Mac, which is impressive considering the features it offers.
Where It Falls Short
Sophos Anti-Virus for Mac isn't perfect. Even though it's fairly resource light, it wasn't the lightest in our tests: it just hit the sweet spot between resources and features. Also, support for Mountain Lion support came a few months after its launch, so Sophos wasn't exactly right there with those people who upgraded on launch day.
ClamXav 2 uses the open source ClamAV virus scanning engine. It can also detect both WIndows and OS X malware, scan on demand or on a regular schedule, and it's probably a bit more lightweight and easy on system resources than Sophos. It's compatible with OS X 10.5 or higher. The main issue with ClamXav is that its definitions come a bit more sporadically than we'd like (daily, usually, sometimes, if they feel like it) and while performing scans is easy, tweaking all of the settings and getting the app scanning proactively is a little more difficult than I'd ideally like. Still, it's an excellent alternative, and one of the first you should check out if Sophos isn't cutting it for you.
Avast! Free Antivirus for Mac is the Mac version of our current favourite for Windows. The researchers at AV Comparitives found that Avast detected 100 per cent of the Mac malware that went through it, an honour that few other utilities won (they didn't test Sophos, unfortunately). It's free, it works, it's lightweight, but the only catch is that it only scans for Mac-specific malware. That won't matter to you if you're in an all-Mac ecosystem, but if you, like most of us, share the world with Windows users, thinking of them doesn't hurt.
Avira is another free utility worth a look. It also picked up 100 per cent of the Mac malware that passed through it with no false positives. Avira's UI and options are perfect for non-technical users, and it offers strong protection against known Mac threats. Again, there's no Windows protection in the app, and both the scheduling and custom scan options are a bit anaemic, so power users may want to shy away from it. If you're installing it on your non-technical friend or family-member's Mac however, it's a great option.
For more suggestions, be sure to check out AV Comparitives' full 2012 report on Mac antivirus tools -- there are more in there we didn't list here.
Lifehacker's App Directory recommends the best applications and tools across multiple platforms.