Over the past two years a lot of articles, processes, techniques and tools have been published on how to do Threat Hunting. I have been following the trend with great interest whether it be which process works best, methods and procedures to follow and adapt to your environment, and finally logs or tools that can help the hunt.

I have taken a simplistic approach to Threat Hunting and for me it is: Proactively searching for threats missed by every defenses in the enterprise. We are Threat Hunting for the unknown! Assume something is already compromised.

That is a tall order, where do we start? There first step is to know the network I'm defending. In order to do this well, it means to have a pretty good knowledge what the network looks like (i.e. network diagrams, traffic flows, client → server relationship, etc) and the type of activity considered normal. Anything deviating from that "normal" need to be investigated.

The next step is to collect the logs that will help with the hunt; such as host and network logs to fuse traffic flow in a way that can help identify unusual pattern of activity.

Some of the logs that might be important to collect (not exhaustive) might be: proxy, web & application servers, DNS, host-based, antivirus, EndPoint Detection Response (EDR), firewall, etc. In the end, each organization is unique. Using the Mitre ATT&CK framework can help the hunt by identifying the tactics and techniques that will help capture the most promising logs to detect and identify unusual behavior happening in the network.

Over the years, several handlers have published various articles on Threat Hunting whether it be process, methods or tools like rita [1][2] or HELK [3] to help with the hunt.

If you are interested in learning how to conduct Threat Hunting in your network and missed Active Countermeasures' last course, they are conducting another free, one-day, Cyber Threat Hunting Training online course on the 4 April where you can see the course content and register here.

[1] https://isc.sans.edu/forums/diary/DeepBlueCLI+Powershell+Threat+Hunting/25730
[2] https://isc.sans.edu/forums/diary/Using+RITA+for+Threat+Analysis/23926
[3] https://isc.sans.edu/forums/diary/Threat+Hunting+Adversary+Emulation+The+HELK+vs+APTSimulator+Part+1/23525
[4] https://www.activecountermeasures.com/free-tools/rita/
[5] https://register.gotowebinar.com/register/6883873380989840395
[6] https://attack.mitre.org/

-----------
Guy Bruneau IPSS Inc.
My Handler Page
Twitter: GuyBruneau
gbruneau at isc dot sans dot edu