On "Advanced" Network Security Monitoring

My TaoSecurity News page says I taught 41 classes lasting a day or more, from 2002 to 2014. All of these involved some aspect of network security monitoring (NSM). Many times students would ask me when I would create the "advanced" version of the class, usually in the course feedback. I could never answer them, so I decided to do so in this blog post.

The short answer is this: at some point, advanced NSM is no longer NSM. If you consider my collection - analysis - escalation - response model, NSM extensions from any of those phases quickly have little or nothing to do with the network.

Here are a few questions I have received concerned "advanced NSM," paired with the answers I could have provided.

Q: "I used NSM to extract a binary from network traffic. What do I do with this binary?"

A: "Learn about reverse engineering and binary analysis."

Or:

Q: "I used NSM to extra Javascript from a malicious Web page. What do I do with this Javascript?"

A: "Learn about Javascript de-obfuscation and programming."

Or:

Q: "I used NSM to capture an exchange between a Windows client and a server. What does it mean?"

A: "Learn about Server Message Block (SMB) or Common Internet File System (CIFS)."

Or:

Q: "I used NSM to capture cryptographic material exchanged between a client and a server. How do I understand it?"

A: "Learn about cryptography."

Or:

Q: "I used NSM to grab shell code passed with an exploit against an Internet-exposed service. How do I tell what it does?"

A: "Learn about programming in assembly."

Or:

Q: "I want to design custom hardware for packet capture. How do I do that?"

A: "Learn about programming ASICs (application specific integrated circuits)."

I realized that I had the components of all of this "advanced NSM" material in my library. I had books on reverse engineering and binary analysis, Javascript, SMB/CIFS, cryptography, assembly programming, ASICs, etc.

The point is that eventually the NSM road takes you to other aspects of the cyber security landscape.

Are there *any* advanced area for NSM? One could argue that protocol analysis, as one finds in tools like Bro, Suricata, Snort, Wireshark, and so on constitute advanced NSM. However, you could just as easily argue that protocol analysis becomes more about understanding the programming and standards behind each of the protocols.

In brief, to learn advanced NSM, expand beyond NSM.

Comments

@infosec42 said…
Overall I agree with you. I'm surprised you don't mention learning about / understanding IDS signatures though? I feel like that is a more "advanced" part of analysis that analysts need to learn about that's hard to come by.
2:06 PM
Richard Bejtlich said…
That's a good point. I suppose writing good signatures is an advanced task.
2:07 PM
Unknown said…
I might add to that list: Security Automation and Orchestration. (Full disclosure, this is what my current employer makes.) So you've extracted a binary? Send it to the analysis and reputation services and products for evaluation, and if it's malicious, send the IOCs to your enforcement devices, have your endpoint solutions hunt and block, go back to the packets and look for the phone-homes, etc.
5:13 PM
Anonymous said…
Advanced NSM comes from correlating several low-fidelity or high false-positive indicators which alone would be noise, but collectively are significant. As an example, you might have an IDS signature which is tuned as noise and doesn't show in the main channel, but if you combine an OS event for failed logons, and a FIM alert for a new file creation, you now have something which should be investigated.
6:24 PM
Post a Comment

Popular posts from this blog

Zeek in Action Videos

Image
This is a quick note to point blog readers to my Zeek in Action YouTube video series for the Zeek network security monitoring project .  Each video addresses a topic that I think might be of interest to people trying to understand their network using Zeek and adjacent tools and approaches, like Suricata, Wireshark, and so on.  I am especially pleased with Video 6 on monitoring wireless networks . It took me several weeks to research material for this video. I had to buy new hardware and experiment with a Linux distro that I had not used before -- Parrot .  Please like and subscribe, and let me know if there is a topic you think might make a good video.
Read more

MITRE ATT&CK Tactics Are Not Tactics

Image
Just what are "tactics"? Introduction MITRE ATT&CK  is a great resource, but something about it has bothered me since I first heard about it several years ago. It's a minor point, but I wanted to document it in case it confuses anyone else. The MITRE ATT&CK Design and Philosophy document from March 2020 says the following: At a high-level, ATT&CK is a behavioral model that consists of the following core components: • Tactics, denoting short-term, tactical adversary goals during an attack; • Techniques, describing the means by which adversaries achieve tactical goals; • Sub-techniques, describing more specific means by which adversaries achieve tactical goals at a lower level than techniques; and • Documented adversary usage of techniques, their procedures, and other metadata. My concern is with MITRE's definition of "tactics" as "short-term, tactical adversary goals during an attack," which is oddly recursive. The key word in the tacti...
Read more

New Book! The Best of TaoSecurity Blog, Volume 4

Image
  I've completed the TaoSecurity Blog book series . The new book is  The Best of TaoSecurity Blog, Volume 4: Beyond the Blog with Articles, Testimony, and Scholarship .  It's available now for Kindle , and I'm working on the print edition.  I'm running a 50% off promo on Volumes 1-3 on Kindle through midnight 20 April. Take advantage before the prices go back up. I described the new title thus: Go beyond TaoSecurity Blog with this new volume from author Richard Bejtlich. In the first three volumes of the series, Mr. Bejtlich selected and republished the very best entries from 18 years of writing and over 18 million blog views, along with commentaries and additional material.  In this title, Mr. Bejtlich collects material that has not been published elsewhere, including articles that are no longer available or are stored in assorted digital or physical archives. Volume 4 offers early white papers that Mr. Bejtlich wrote as a network defender, either for technica...
Read more