There are a number of solutions on the market for scanning a Mac for files that have become infected with a virus or macro-virus. Many of these have a negative return on investment. So customers can instead go the open source route to scan files and quarantine them. And customers can use Jamf Pro to enable doing so. This page is meant to provide a quick and dirty guide to doing so, along with how this might be packaged and potentially tracked with Jamf Pro. First, we’ll install and configure a free tool called clamav.

There are a number of ways to install clam. For this example, just to get it done quickly, we’ll use homebrew which is simply brew with the install verb and clamav as the recipe to be brewed:

brew install clamav

This is going to place your configuration files in /usr/local/etc/clamav and these cannot be used as those supplied by default are simply sample configurations. Because the .sample files have a line that indicates they are an “Example” they cannot be used. So we’ll copy the sample configuration files for freshclam.conf and clamd.conf (the demonized version) and then remove the Example line using the following two lines:

cp /usr/local/etc/clamav/freshclam.conf.sample /usr/local/etc/clamav/freshclam.conf; sed -ie 's/^Example/#Example/g' /usr/local/etc/clamav/freshclam.conf
cp /usr/local/etc/clamav/clamd.conf.sample /usr/local/etc/clamav/clamd.conf; sed -ie 's/^Example/#Example/g' /usr/local/etc/clamav/clamd.conf

Next, we’ll need to update the virus definitions for clamav. This can be run without the fully qualified file path but we are going to go ahead and include it as some computers might have another version installed (e.g. via macOS Server):

freshclam -v

The initial scan should cover the full hard drive and can be run as clamscan

sudo /usr/local/bin/clamscan -r — bell -i /

Your routinely run jobs should be setup to a quarantine location. Because all users should be able to see their data that was quarantined we would write this to /Users/Shared/Quarantine. We can then use a standard clamscan to scan the system and then “move” quarantined items to that location and log those transactions to /Users/Shared/Quarantine/Quarantine.txt.

sudo mkdir /Users/Shared/Quarantine
sudo clamscan -r — scan-pdf=yes -l /Users/Shared/Quarantine/Quarantine.txt — move=/Users/Shared/Quarantine/ /

You can then use an Extension Attribute to read the Quarantine.txt file:

#!/bin/bash
 
#Read Quarantine
 
result = `cat /Users/Shared/Quarantine/Quarantine.txt`
 
#Echo Quarantine into EA
 
echo "<result>$result</result>"

Every environment is different. When combined with standard mrt scans using the built-in malware removal tool for macOS, clamAV can provide a routine added protection to isolate and help you remediate infections. 

Finally, it seems like I have yet to discuss antivirus and malware without getting into the conversation about whether you need it or not. In this post I am in no way taking a side on that argument, and it’s worth mentioning that I’m also not using “antivirus” to exclusively reference viruses but instead including all forms of malware. Rather, I’m exploring options for scanning systems routinely.You can easily run this nightly and parse the quarantine.txt file prior to picking it up with the Extension Attribute routinely in order to provided an additional layer of defense against potential threats to the Mac. Putting all of this into a software package would be rudimentary, and could benefit many organizations without putting our coworkers through the performance hit that many a commercial antivirus solution brings with it.

Here’s a new extension attribute at https://github.com/krypted/ituneshash/blob/master/ituneshash.sh for grabbing the hash ID used for iTunes Store accounts, useful with VPP: #!/bin/sh # # # #Jamf Pro Extension Attribute to return the App Store Account Hash for iTunes #Note that the return is null if one is not found # # result=`/usr/libexec/mdmclient QueryAppInstallation | grep iTunesStoreAccountHash | sed '/.*\"\(.*\)\".*/ s//\1/g'` echo "<result>$result</result>" The output is something like:
<result>oBSmAAAa0nUAAACBHe5AaALlNBg=</result>
Which would bring the string into Jamf Pro

Built a quick extension attribute for Jamf Pro environments to check if TouchID is enabled and report back a string in $result – this could easily be modified and so I commented a few pointers for environments that might need to modify it (e.g. to check for user-level as it’s currently system-level). To see/have the code, check https://github.com/krypted/TouchID_check.