Last Updated: 2008-10-07 18:28:15 UTC
by Jim Clausing (Version: 4)
One of the sources we use to identify incidents is the network-based intrusion detection system (NIDS) that most of our enterprises have, at least at the border, at our known internet connections. The NIDS, however, can be pretty noisy, how do we turn the noise into actionable data? How much access does the incident handler have to the raw NIDS data? As Steve pointed out yesterday, the alerts from the NIDS are just events, they don't become an incident (usually) until these events have been correlated with other data. How do you use NIDS data to indentify incidents requiring activation of your IH process? Let us know via the contact page and this story will be updated throughout the day.
From David: This is a great question, but I'm really interested in the answer to a related question: "How do you use non-NIDS data to validate NIDS alerts?" I don't have to tell you guys that the amount of data that comes from a single alert is sometimes very skimpy, and doesn't always provide good decision-making support.
As I evaluate an alert, I routinely ask myself a series of questions, then try to find the answers. In most cases, the questions are something like:
1. Was this an actual attack?
2. If so, was the attack successful?
3. What other systems may also have been attacked?
4. What activities did the intruder try to carry out?
5. What other resources were they able to gain access to?
6. How should we contain, eradicate and recover from the intrusion?
Most of these questions are difficult to answer just by looking at an individual alert, but I can usually answer them quite easily (and quickly) by examining sessions and/or PCAP data. Well, except for #6, which is usually pretty tricky.
I'm curious to know what your other readers are doing to validate their NIDS alerts, even before they feed into the incident handling processes.
So, what do you think? Keep the thoughts and ideas coming. Over the next couple of days, we will be looking at some other non-NIDS sources for identification, but there's no reason we can't start some of that conversation today.