App of the Week: ClamXav

I am a fan of open-source, no doubt about it.  Part of it is certainly that open-source stuff tends to be free (LibreOffice, Firefox, just to name a couple), but it also helps bring people together.  Open-source is almost inherently a community activity.  It also means anyone who knows any code can generally take open source software and change it to their needs, so long as they give at least some reference to the original code.  And open-source also tends to lead to innovation.  I see all of these things and plenty of security in ClamXav.

ClamXav is an open source antivirus for Mac.  ClamXav is based on the popular Clamav, a commonly used, open source antivirus on Linux, as well as Windows.  ClamXav takes that engine and lets it run on OSX (hence the X in ClamXav).  But Clamav has traditionally been run as a command line program, simply meaning there’s no easy buttons to push.  ClamXav not only adds an easy user interface, but also has a sentry feature that actively watches your files for any suspicious activity.  The interface is

ClamXav's main screen

really simple, with big buttons labeled for starting and stopping scans, updating the definitions, and preferences.  There’s also a list of quick folders to scan, though you can always set up other scans, even your whole hard drive.  The preferences are also fairly easy to go through and set up, setting up simple tasks like what to do if the app detects a virus, email alerts, scheduling scans, etc.  The app also allows more advanced users to perform tasks like running other command line utilities, install their own antivirus engine, etc.

Performing a scan tells you in real-time any malware it finds, gives them to you in a list, and can be immediately moved to quarantine for review or deleted.  One confusing thing about the scan is that it tells you how many types of viruses the app can detect, but at first glance this almost looks like how many viruses you have on the system, which is simply not true.

One of the big things I like about ClamXav is the fact that it can not only detect Mac malware, but also Windows malware.  You might wonder why this a big deal; Windows code won’t run on Mac, so Windows viruses won’t affect that Mac OS.  The main reason having an antivirus that scans for Mac and Windows malware on the Mac is to prevent what is called the “downstream effect”.  If a Mac gets a Windows virus, the virus can’t do anything because neither the Mac nor Windows understands what the other is (it’s like two people having a conversation in two different languages, or trying to build something when you can’t read the instructions).  However, the virus could be transferred accidentally from Mac to a Windows computer via an email, a bad link, a flash drive, etc.  And if you have friends and family that use Windows…i think you get the idea.  While this means that ClamXav takes longer to scan your hard drive than if it only searched for Mac malware, I think it’s a worthy trade.

All this being said, there are a couple of things to note.  First, the version in the Mac App Store is different from that being offered on ClamXav’s website.  The main differences are that the Mac App Store version does not allow for user virus engines, but more importantly it does not come bundled with Sentry.  Sentry basically is the active scanner that comes with the normal version of ClamXav, and scans your files as they come in, much like any other antivirus would.  There are other problems however; ClamXav tends to be especially heavy when scanning your hard drive, and tends to noticeably take a few hours.  If you run this scan, it’s generally easier just to let the scan run while you leave your Mac to do something else.  Another problem is ClamXav tends to have a few false positives when scanning.  Almost anytime when I scan, a scholarship website email that I use is constantly flagged as a trojan horse.  This seems like something that needs to be fixed.  The only other problem is that when app is done scanning, it tells you the viruses found, and the number of viruses it can scan for.  These are both good, but when you are doing a quick look over, seeing the “viruses scanned” and a number in the tens of thousands is a little disconcerting until you read the fine print.  It would be better if the program could make this a little more clear.

All in all, ClamXav is still a good antivirus, especially for those who are diehard open-source fans.  I would recommend getting ClamXav from the official site, rather than the Mac App Store.  It is available for free either way, though a donation is requested.  If you have any questions, comments, or suggestions about this or any other topic, leave a comment below or email me at  You can also check me out on Facebook, Twitter, and YouTube by hitting the buttons on the top of your screen.  You can also check out my Google Plus Page.  Thanks!

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