SOC-CMM vs SIM3: SOC maturity versus CSIRT maturity

The most common mistake we see in maturity work is one of scope, not method. SIM3 (the Security Incident Management Maturity Model) answers the question: how mature is our incident response team as an organization? SOC-CMM answers a different one: how mature and capable is our SOC across everything it does, from detection through to board reporting? Different questions demand different models.

SIM3 is maintained by the Open CSIRT Foundation and grew out of the European incident response community. Its unit of analysis is the CSIRT: the team that receives, coordinates and resolves confirmed incidents. SOC-CMM, created by Rob van Os in 2016 and now at version 2.4, takes the complete SOC as its unit: the people, processes, technology and services that detect and respond continuously. If your organization runs both teams, decide what each model will measure before anyone starts arguing about scores.

SIM3 organizes CSIRT maturity into four quadrants: Organisation (mandate, authority, institutional position), Human (skills, training, team resilience), Tools (incident handling and analysis tooling) and Processes (how incidents are detected, escalated and closed). Each quadrant contains a set of concrete parameters that are scored individually.

Each parameter is rated on a 0-4 scale. The logic of the scale is formalization: at the lower levels a practice is absent or implicit, known only tacitly within the team; at the middle levels it is written down and approved; at the top level it is also actively reviewed and audited. That logic matches what an accreditor or a regulator wants to verify in a CSIRT: that the mandate, procedures and controls do not live in the heads of three people.

What SIM3 does not measure matters as much as what it does. It does not assess detection effectiveness, use-case coverage against a framework such as MITRE ATT&CK, the capability of the deployed technology, or the catalog of services the team delivers to internal or external clients. For a pure CSIRT that is a reasonable boundary. For a SOC it is not enough.

SOC-CMM assesses five domains (Business, People, Process, Technology and Services) across 27 aspects, with continuous 0-5 scoring. The structural difference sits in two domains SIM3 does not cover: Technology, where SOC-CMM measures capability rather than mere presence of tooling, and Services, where it assesses monitoring, threat intelligence, hunting and response as services with a catalog, a scope and their own metrics.

The scales also differ in intent. SIM3 measures degree of formalization per parameter in four steps. SOC-CMM produces a continuous score that separates maturity (how well something is managed) from capability (how complete the deployment is), which is what lets you prioritize investment: a SOC can run capable technology on immature processes, or the reverse. The SOC-CMM 2026 report data illustrates that typical imbalance: an average of 2.7 in Technology against 2.2 in Services and 2.3 in both People and Process.

SIM3 is the natural reference when the goal is recognition within the incident response community. Trusted Introducer certification under TF-CSIRT is based on reaching minimum SIM3 levels on defined parameters. FIRST uses SIM3 as the self-assessment basis in its membership process. And ENISA has adopted it as the instrument for measuring and developing the maturity of Europe's national CSIRTs, within the capability obligations the NIS2 Directive (EU) 2022/2555 places on member states.

• Your team is a CSIRT with a response and coordination mandate, not a SOC running continuous detection.
• You are pursuing TF-CSIRT accreditation or certification, FIRST membership, or alignment with ENISA's criteria.
• You need to demonstrate institutional formalization: a written, approved and audited mandate, authority and procedures.

If the team detects as well as responds, SIM3 falls short by design. A corporate SOC or an MSSP needs evidence on detection coverage, use-case management, the capability of the SIEM and the rest of the stack, and the quality of the services it delivers. SOC-CMM is the only one of the two models that structures that evidence, and the certifiable version adds 127 controls across three levels for organizations that need formal verification.

There is a second, less comfortable argument: self-assessment trends optimistic. The 2026 report data shows self-assessments overestimate maturity by around 0.6 points compared with an independent assessment. That applies to any model, SIM3 included. If the result is going to a board or a regulator, the independent third-party assessor matters as much as the model you choose.

A simple rule. If the team only handles confirmed incidents and seeks recognition in the CSIRT community, use SIM3. If the team also detects, hunts, runs threat intelligence or delivers services to third parties, use SOC-CMM. If you have both teams, do not choose: assign one model to each.

In banking, energy and telecom it is common for the SOC and the CSIRT to be separate teams with complementary responsibilities: the SOC detects and triages, the CSIRT coordinates and resolves major incidents. In that scenario the coherent approach is to assess the SOC with SOC-CMM and the CSIRT with SIM3, then consolidate both results into a single roadmap with cross-team priorities. The friction point to watch is the handover: SOC-to-CSIRT escalation appears in SOC-CMM's Process domain and in SIM3's Processes quadrant, and the two assessments must tell the same story.

For entities under DORA (Regulation (EU) 2022/2554) or NIS2 the combination carries an extra benefit: the maturity evidence covers both continuous detection capability and formal incident management and reporting, which are distinct obligations in both texts. No regulator mandates a specific model, but a file containing two coherent matrices and a dated improvement plan answers an inspection far better than any generic statement.