How to find out if your Mac is infected with malware

One of the favorite Mac vs. PC myths is “PCs are slow, they always crash, and get viruses!” The corollary to that would be “Macs never get viruses.” That’s getting harder to say with a straight face.

In April, research firm Sophos released a study that found one in five Macs was infected with malware. The study comes from a survey of 100,000 Macs that downloaded Sophos’s free Mac antivirus software, so it was a decent sample size.

(It’s important to note that these malware programs are Windows programs, so they aren’t able to do anything unless the Mac runs Windows software. They are mostly harmless.)

No matter what software is affected though, this increasing trend demonstrates that hackers are able to sneak unwanted software payload onto Apple  computers. Currently, 2.7 percent of infected Macs are infected with Mac OS-compatible malware.

Malware such as the Flashfake Mac OS X botnet have been reported to have infected 500,000 Macs. It disguises itself as an Adobe Flash installer and hijacks the search engine results that appear in a browser.

How to find out if your Mac is infected

There are several free applications to help you find out if your Mac is infected:

• Download the free Sophos antivirus software
• Download the free Dr. Web Light from the Apple App Store
• Download a couple AppleScripts hosted on CloudApp
• CNET’s MacFixIt has a good list of trusted antivirus apps.

The word “trusted” on the last item is important because the list is part of a post on a new malware which specifically targets Macs. Fake security applications like “Mac Defender,” “Mac Security,” and “Mac Protector” have tricked unsuspecting users into installing malware instead of antivirus software. Luckily this one is fairly obvious to find (read the post for very good instructions.)

To avoid future malicious downloads, the post recommends turning off any option that automatically opens or installs downloaded files, as well as restricting downloads to specific folders.

The only guaranteed way to avoid malware is to not connect your Mac to the Internet. Being careful while using the Internet helps, but even the most computer-savvy users can get infected with malware without knowing it. In lieu of completely disconnecting your computer from the Internet, the most effective deterrent seems to be keeping up with the latest Apple security updates.