May 7, 2015

Security Monitoring / SIEM Use-Cases

Filed under: Log Analysis,Security Information Management,Visualization — @ 7th of May 2015, 15:40

As it happens, I do a lot of consulting for companies that have some kind of log management or SIEM solution deployed. Unfortunately, or maybe not really for me, most companies have a hard time figuring out what to do with their expensive toys. [It is a completely different topic what I think about the security monitoring / SIEM space in general – it’s quite broken.] But here are some tips that I share with companies that are trying to get more out of their SIEMs:

  • First and foremost, start with use-cases. Time and time again, I am on calls with companies and they are telling me that they have been onboarding data sources for the last 4 months. When I ask them what they are trying to do with them, it gets really quiet. Turns out that’s what they expected me to tell them. Well, that’s not how it works. You have to come up with the use-cases you want/need to implement yourself. I don’t know your specific environment, your security policy, or your threat profile. These are the factors that should drive your use-cases.
  • Second, focus on your assets / machines. Identify your most valuable assets – the high business impact (HBI) machines and network segments. Even just identifying them can be quite challenging. I can guarantee you though; the time is well spent. After all, you need to know what you are protecting.
  • Model a set of use-cases around your HBIs. Learn as much as you can about them: What software is running on them? What processes are running? What ports are open? And from a network point of view, what other machines are they communicating with? What internal machines have access to talk to them? Do they talk to the outside world? What machines? How may different ones? When? Use your imagination to come up with more use-cases. Monitor the machines for a week and start defining some policies / metrics that you can monitor. Keep adopting them over time.
  • Based on your use-cases, determine what data you need. You will be surprised what you learn. Your IDS logs might suddenly loose a lot of importance. But your authentication logs and network flows might come in pretty handy. Note how we turned things around; instead of having the data dictate our use-cases, we have the use-cases dictate what data we collect.
  • Next up, figure out how to actually implement your use-cases. Your SIEM is probably going to be the central point for most of the use-case implementations. However, it won’t be able to solve all of your use-cases. You might need some pretty specific tools to model user behavior, machine communications, etc. But also don’t give up too quickly. Your SIEM can do a lot; even initial machine profiling. Try to work with what you have.

Ideally you go through this process before you buy any products. To come up with a set of use-cases, involve your risk management people too. They can help you prioritize your efforts and probably have a number of use-cases they would like to see addressed as well. What I often do is organize a brainstorming session with many different stakeholders across different departments.

Here are some additional resources that might come in handy in your use-case development efforts:

  • Popular SIEM Starter Use Cases – This is a short list of use-cases you can work with. You will need to determine how exactly to collect the data that Anton is talking about in this blog post and how to actually implement the use-case, but the list is a great starting point.
  • AlienVault SIEM Use-Cases – Scroll down just a bit and you will see a list of SIEM use-cases. If you click on them, they will open up and show you some more details around how to implement them. Great list to get started.
  • SANS Critical Security Controls – While this is not specifically a list of SIEM use-cases, I like to use this list as a guide to explore SIEM use-cases. Go through the controls and identify which ones you care about and how you could map them to your SIEM.
  • NIST 800-53 – This is NIST’s control framework. Again, not directly a list of SIEM use-cases, but similar to the SANS list, a great place for inspiration, but also a nice framework to follow in order to make sure you cover the important use-cases. [When I was running the solution team at ArcSight, we implemented an entire solution (app) around the NIST framework.]

Interestingly enough, on most of my recent consulting calls and engagements around SIEM use-cases, I got asked about how to visualize the data in the SIEM to make it more tangible and actionable. Unfortunately, there is no tool out there that would let you do that out of the box. Not yet. Here are a couple of resources you can have a look at to get going though:

  • secviz.org is the community portal for security visualization
  • I sometimes use Gephi for network graph visualizations. The problem is that it is limited to only network graphs. Very quickly you will realize that it would be nice to have other, linked visualizations too. You are off in ‘do it yourself’ land.
  • There is also DAVIX which is a Linux distro for security visualization with a ton of visualization tools readily installed.
  • And – shameless plug – I teach log analysis and visualization workshops where we discuss more of these topics and tools.

Do you have SIEM use-cases that you find super useful? Add them in the comments!

1 Comment »

  1. Use Cases from the Secnology website:
    http://www.secnology.com/wp-content/uploads/2015/04/SECNOLOGY_100_UseCases_15D27.pdf

    Comment by Max — December 15, 2015 @ 2:01 am

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