Apple does its part to prevent malware episodes from infecting OS X, but malware comes in many flavors, so a free utility which scans your Mac looking for the most recent and persistent malware scourge is handy and beneficial.
That’s KnockKnock (as in, “Who’s there?”), a free Mac malware scanner utility. The user interface is straightforward and displays items that may not seem necessary, but which are usually home to malware attempts.
You’ll see browser extensions, OS X kernel extensions, login and launch items, and more; plus details about each item and whether or not it’s a candidate for malware exposure.
KnockKnock detects known and recently deployed malware that could be lurking on the Mac. Click the Start Scan button and the action begins. If it finds a known virus (or, unknown, but something that looks like a known virus), worm, or other malware, you’ll be able to view the file in the Mac’s Finder.
The key to success with KnockKnock appears to be VirusTotal integration which helps to identify malware components, otherwise you might be troubled by how many different files the app can scan and flag. The real question here is simple. Does KnockKnock work? Do you need it?
I can’t answer the first question because, 1) it didn’t find any malware on my Mac, or, perhaps because of, 2) there is no malware on my Mac, or, worse, 3) there’s malware on my Mac that it could not find.
As to the second question, KnockKnock is free and it might work for you.