18. October 2011 · Comments Off on Practical SIEM Deployment | SecurityWeek.Com · Categories: blog · Tags: , ,

Practical SIEM Deployment | SecurityWeek.Com. Chris Poulin, from Q1 Labs, has an excellent article in SecurityWeek on practical SIEM deployment.

Chris points out that SIEM is more challenging than say Anti-Virus because (1) there are so many possible use cases for a modern SIEM and (2) context is a factor.

Chris describes the general use cases that apply to most organizations and are mostly ready to deploy using out-of-the-box rules, dashboard widgets, reports, and saved searches:

  • Botnet detection
  • Excessive authentication failures
  • Traffic from darknets
  • IDS alerts that a particular attack is targeting an asset that the VA scanner confirms is vulnerable to that exploit
These cover many of the controls in compliance mandates and provide a good foundation for your log management program, not to mention they’re the main log sources used by default rules in most SIEMs. 
It surely makes sense that Phase 1 of a SIEM project should focus on collecting telemetry from key log sources and implementing the general use cases itemized above.
Chris points out that while IPS/IDS is core telemetry, it should not be part of Phase 1 because there can be a lot of tuning work needed if the IPS/IDSs have not already been tuned. So I will call IPS/IDS integration Phase 2, although Phase 1 includes basic IPS/IDS – Vulnerability matching.
If the IPS/IDSs are well tuned for direct analysis using the IPS/IDS’s console, then by all means include them in phase one. In addition, if the IPS/IDSs are well-tuned, it’s been my experience that you ought to consider “de-tuning” or opening up the IPS/IDSs somewhat and leverage the SIEM to generate more actionable intelligence.
Chris says that the next phase (by my count, Phase 3) ought to be integrating network activity, i.e. flows if the SIEM “has natively integrated network activity so it adds context and situational awareness.” If not, save flow integration for organization-specific use cases.
Network activity can automatically discover and profile assets in your environment, and dramatically simplify the tuning process. Vulnerability Assessment (VA) scanners can also build an asset model; however, VA scanners are noisy, performing active probes rather than passively watching the network, and only give you a point -in-time view of the network. To be sure, VA scanners are core telemetry, and every SIEM deployment should integrate them, but not as a replacement for native network activity monitoring, which provides a near-real-time view and can alert to new assets popping up, network scans—even low and slow ones—and DDoS attacks. And if you’re monitoring network activity and collecting flows, don’t forget to collect the events from the routers and switches as well.
At this point, with the first three phases complete, the security team has demonstrated the value of SIEM and is well down the product learning curve. Therefore you are ready to focus on organization-specific use cases (my Phase 4), for example adding application and database logs.