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Application Whitelisting
Specifying which applications can execute, leaving everything else implicitly or explicitly denied

What Is It?

I consider a firewall to be a Yes / No device when you strip away all the “Next Generation” and Unified Threat Management (UTM) pieces. To some degree, Application Whitelisting works the same way by specifying which applications can execute (The Whitelist) leaving everything else implicitly or explicitly denied (The Blacklist). Granted, there will always be some that fall in the middle (The Greylist) but those should be reserved for administrative decision and not for the user to decide. By the way…. make sure the aforementioned firewall also has a default “deny all” rule in place! I have seen many installations where the final rule was an “Allow All” with millions of hits against it.

Where Do I Start?

The first place to start should be understanding your information systems and which applications are needed to perform your business functions. If you don’t have this list already, please create it and engage a security specialist to help if needed. This will essentially become your “Whitelist”. It’s worth noting not every team in your organisation will use the same list…. there may be a core list (such as office applications) for everyone but different lists for other roles (such as Payroll and HR). Getting a handle on what applications you need and which you don’t want is crucial otherwise you can find yourself preventing good and allowing bad like a lousy B-grade superhero movie.

How I do I Make It Work?

You probably already have the required hardware and software to make this a reality. Most modern endpoint protection applications, such as those from Symantec, Kaspersky, Sophos, and McAfee can perform application whitelisting. Modern UTM firewalls that offer application control are not really “Whitelisting” but can add another layer of defence if you choose.

It’s time to take stock and figure out what your business needs and what it doesn’t want. That comes down to what makes your business tick – the very applications you rely on.


Many, which is why I recommend getting the right people involved and this means more than just the IT team. Management also needs to support and sign off on this initiative. Having it as part of your information security / general IT policies is also recommended. You need to know exactly what applications are on your network and which ones are needed. It’s not an easy voyage, but one worth taking. At the heart of it, executing code is the cause of a lot of breaches. Also consider that it’s not always malware; sometimes your own tools and utilities can be used against you!

Ghosts in the Machine?

It’s us, plain and simple. At the end of the day, we just want to do our jobs, get paid, and go home to our families. Be ready to uncover shadow IT and related shadow data that often arise because of shortcuts (well-intended or otherwise) that we use to get the job done. Application Whitelisting can really help secure the environment but be prepared for some resistance from the masses.

Anything Missing?

Make sure you have the endpoint protection applied to every host that you can and think beyond just workstations…. locking down the ability of applications to execute on your servers – especially database servers and web servers – can be an invaluable tactic.

Disclaimer: The thoughts and opinions presented on this blog are my own and not those of any associated third party. The content is provided for general information, educational, and entertainment purposes and does not constitute legal advice or recommendations; it must not be relied upon as such. Appropriate legal advice should be obtained in actual situations. All images, unless otherwise credited, are licensed through ShutterStock