The difference between NIST CSF maturity and managing cyber risk

Yesterday marked the fifth anniversary of what we here at elevenM think is the best cyber security framework in the world, the NIST Cybersecurity Framework (CSF). While we could be writing about how helpful the framework has been in mapping current and desired cyber capabilities or prioritising investment, we thought it important to tackle a problem we are seeing more and more with the CSF: The use of the CSF as an empirical measurement of an organisation’s cyber risk posture.

Use versus intention

Let’s start with a quick fact. The CSF was never designed to provide a quantitative measurement of cyber risk mitigation. Instead, it was designed as a capability guide. A tool to help organisations map out their current cyber capability to a set of capabilities which NIST consider to be best practice.

NIST CSF ’Maturity’

Over the past five years, consultancies and cyber security teams have used the CSF as a way to demonstrate to those not familiar with cyber capabilities, that they have the right ones in place. Most have done this by assigning a maturity score to each subcategory of the CSF. Just to be clear, we consider a NIST CSF maturity assessment to be a worthwhile exercise. We have even built a platform to help our clients to do just that. What we do not support however, is the use of maturity ratings as a measurement of cyber risk mitigation.

NIST CSF versus NIST 800-53

This is where the devil truly is in the detail. For those unfamiliar, NIST CSF maturity is measured using a set maturity statements (note that NIST have never produced their own so most organisations or consultancies have developed proprietary statements: elevenM included) against the Capability Maturity Model (CMM). As you can therefore imagine, the assessment that would be performed to determine one maturity level against another is often highly subjective, usually via interview and document review. In addition to this, these maturity statements do not address the specific cyber threats or risks to the organisation but are designed to determine if the organisation has the capability in place.

NIST 800-53 on the other hand is NIST’s cyber security controls library. A set of best practice controls which can be formally assessed for both design and operating effectiveness as part of an assurance program. Not subjective, rather an empirical and evidence-based assessment that can be aligned to the CSF (NIST has provided this mapping) or aligned to a specific organisational threat. Do you see what we are getting at here?

Which is the correct approach?

Like most things, it depends on your objective. If you want to demonstrate to those unfamiliar with cyber operations that you have considered all that you should, or if you want to build a capability, CSF is the way to go. (Noting that doing the CSF maturity assessment without assessing the underlying controls limits the amount of trust stakeholders can place on the maturity rating)

If however, you want to demonstrate that you are actively managing the cyber risk of your organisation, we advise our clients to assess the design and operating effectiveness of their cyber security controls. How do you know if you have the right controls to manage the cyber risks your organisation faces? We will get to that soon. Stay tuned.