SIEMs are used for establishing security controls and responding to attacks. From my SimWitty days to my new role managing VioPoint’s SOC, we draw a distinction between these two. For controls-based activities, we think in terms of use cases. A SIEM use case defines a particular way the SIEM gathers and reports on data. For threat-based activities, an abuse case that defines an attacker’s activity and how the organization would detect the activity. The use case drives value and the abuse case protects against value loss.
Abuse Cases Map Possible Paths
An abuse case begins by describing the attacker and their objectives. Who are they? What are they after? What tactics and techniques are these attackers likely to use? From there, the abuse case defines the path the attacker would take to achieve their objectives. For example, a typical abuse may include:
(1) External reconnaissance
(2) Initial breach
(3) Escalate privileges
(4) Persistence
(5) Internal reconnaissance
(6) Lateral breach
(7) Maintain presence
(8) Achieve objective
The modus operandi will thus be modeled for a particular threat.
The Final Step In Monitoring
The final step in using SIEM to respond to attacks is to overlay the abuse case with the technical controls. How would we detect and prevent a particular tactic used in persistence, for example? What about the lateral breach phase in an attack path? Thinking through these controls allows us to give ourselves credit for where we are doing well, and allows us to identify opportunities for enhancing the controls.
To get the most out of a SIEM, from a threat perspective, we create a set of high-level threat models and setup monitoring along the identified attack paths. A well-defined abuse case does just that.
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