What is an MSSP?
An MSSP (Managed Security Service Provider) is an external service provider that manages, monitors and operates cybersecurity services on behalf of an organisation, such as 24/7 security monitoring, SIEM administration, vulnerability management and incident response. The MSSP supplies people, processes and often technology as well, usually from its own SOC. The European NIS2 directive defines an MSSP as a managed service provider that carries out or assists with activities relating to cybersecurity risk management. In industrial environments, specific knowledge of ICS, SCADA and industrial protocols is added to that.
With an MSSP you buy in expertise and continuity, but not your accountability: that always stays with your own organisation.
🧠 Why do organisations choose an MSSP?
An in-house SOC staffed day and night is expensive and hard to recruit for. A 24/7 position covers 8,760 hours a year, which comes to five to six FTE per position. On top of that come licences, training and the challenge of retaining scarce analysts. An MSSP spreads those costs across many customers.
- Continuous monitoring - alerts are also assessed at night and at weekends.
- Faster detection - analysts see patterns across many customers and recognise attack techniques earlier.
- Specialist knowledge - for example in ICS/SCADA security, forensics and threat intelligence.
- Predictable costs - a fixed subscription instead of recruitment and training risks.
- Faster response - fixed playbooks and SLAs with agreed response times.
- Support for compliance - reports and evidence for audits and regulators.
🔧 Which services does an MSSP provide?
| Service | What the MSSP does |
|---|---|
| SIEM administration | Collecting and correlating logs, maintaining use cases and assessing alerts |
| SOC as a service | 24/7 monitoring of systems and networks by analysts |
| Threat Intelligence | Turning information on current threats, attackers and zero-days into detection rules |
| Vulnerability Management | Scanning, prioritising and reporting vulnerabilities |
| Patch Management | Advising on or rolling out security updates |
| Incident Response | Investigation, containment and recovery after intrusions or malware |
| Pentest and Red Team | Periodic attack simulations and technical tests |
| Compliance reporting | Providing evidence for NIS2, IEC 62443 and ISO 27001 |
Not every MSSP delivers everything. Some focus purely on monitoring and report suspicious activity to the customer; others also carry out the response themselves. The US law FISMA only matters if you operate systems for the US federal government; in Europe, NIS2 and ISO 27001 are the frame of reference.
🔄 What is the difference between an MSP, an MSSP, MDR and an in-house SOC?
| Model | Core | Response | Typical customer |
|---|---|---|---|
| MSP | Managing ICT: servers, network, workplaces | Fixing faults, not primarily security | Organisations outsourcing their ICT management |
| MSSP | Managing and monitoring security controls | Mostly notify and advise; response often optional | Mid-sized organisations without their own SOC |
| MDR | Detection and response as a service, often based on EDR or XDR | Responds itself, for example by isolating an endpoint | Organisations that want rapid intervention |
| In-house SOC | Internal analysts and tooling | Fully under own control | Large organisations and critical operators |
| Hybrid | MSSP handles first-line monitoring, own team does triage and response | Shared via agreed escalation | Organisations with OT that want 24/7 coverage |
In practice the terms overlap. Rather than looking at the label, look at what has been contractually agreed about detection, response and authority.
🏭 How does an MSSP work in OT environments?
In OT, priorities differ from IT: availability and safety of the process come first. An MSSP therefore must not simply isolate a system or start a scan on a production network. A specialised OT MSSP or an OT SOC works mainly passively.
| Application | Example |
|---|---|
| OT network monitoring | Passive Monitoring and IDS on Industrial Ethernet via SPAN ports or TAP connections |
| Asset discovery | Inventorying PLCs, HMIs, Drives and SCADA systems through Asset Discovery |
| Historian analysis | Abnormal data collection or unexpected outbound connections from the Historian |
| Remote access auditing | Logging on the Jump Server, MFA and Protocol Filtering for vendors |
| Patch advice | Risk-based advice on firmware and OS updates, aligned with maintenance shutdowns |
OT MSSPs often use platforms such as Claroty, Nozomi Networks, Dragos or Tenable OT Security. It is essential that the MSSP respects the customer’s Purdue zones: sensors and collection servers preferably sit in the DMZ or in the relevant zone, and the connection to the MSSP’s SOC runs outbound only and encrypted. For service providers that integrate or maintain OT systems, IEC 62443-2-4 describes which security processes you may expect.
🔐 What role does an MSSP play under NIS2 and the Dutch Cybersecurity Act?
An MSSP is relevant under NIS2 in two ways.
- The MSSP as a regulated entity - NIS2 lists managed service providers and managed security service providers in Annex I, sector 9 “ICT service management (business-to-business)“. A medium-sized or larger MSSP therefore falls under the directive itself: as an essential entity above the medium-sized enterprise ceilings, otherwise as an important entity. Implementing Regulation (EU) 2024/2690 of 17 October 2024 sets out detailed technical requirements for these providers.
- The MSSP as a supplier - Article 21(2)(d) of NIS2 requires organisations to secure their supply chain, including their relationships with direct service providers. Recital 86 points out that MSSPs are themselves targets of attacks and, because of their close integration, pose a particular risk, so you should select them with increased diligence.
In the Netherlands, NIS2 has been transposed into the Cybersecurity Act (Cyberbeveiligingswet), which entered into force together with the Cybersecurity Decree on 15 August 2026. The Dutch Authority for Digital Infrastructure (RDI) is the coordinating supervisor and the NCSC is the CSIRT for most sectors. Note that the reporting obligation stays with you. An early warning is due within 24 hours, an incident notification within 72 hours and a final report within one month. Make sure the MSSP provides the information you need for that in time.
In addition, Regulation (EU) 2025/37, which entered into force on 4 February 2025, amends the EU Cybersecurity Act (Regulation (EU) 2019/881) to allow European certification schemes for managed security services such as incident handling, penetration testing and security audits. No such scheme exists yet, but it may help you choose a trustworthy MSSP in the future.
🎯 How do you select and contract an MSSP?
A step-by-step approach that works well in practice:
- Define the scope - which systems, sites and zones are covered, and is OT included?
- Choose the model - monitoring only, MDR with response, or hybrid with your own team.
- Test OT knowledge - ask about experience with your protocols, vendors and IEC 62443.
- Agree SLAs - response times per priority, escalation paths and availability outside office hours.
- Define authority - what may the MSSP do itself, and which actions in OT always need approval from operations?
- Secure access - MFA, least privilege, separate accounts per analyst and full logging.
- Safeguard data and exit - where are logs stored (on-premise or in the cloud), for how long, and how do you get them back on termination?
- Exercise together - test the incident response plan with the MSSP at least once a year.
| Point of attention | Common contractual arrangement |
|---|---|
| Response time for a critical alert | Within 15 to 60 minutes, 24/7 |
| Log retention | Often 90 days directly searchable, longer in archive |
| Reporting | Monthly operational, quarterly at management level |
| Assurance on the MSSP | ISO 27001 certificate or SOC 2 report, plus a right to audit |
| Exit | Handover of logs, detection rules and documentation |
The joint advisory AA22-131A from the Five Eyes agencies in May 2022 stressed that attackers exploit the trust between provider and customer. The attack on Kaseya VSA in July 2021, in which ransomware spread through the management software of around 60 service providers to an estimated 800 to 1,500 of their customers, showed how a single provider can become an entry point into many organisations. Treat your MSSP as part of your third-party risk management, and integrate it carefully with your existing tooling and network architecture.
❓ Frequently asked questions
How much does an MSSP cost?
The cost of an MSSP depends on the number of log sources, endpoints and sites and on the services chosen. For most mid-sized organisations a subscription is cheaper than an in-house 24/7 SOC, which quickly requires ten to fifteen staff. OT monitoring is often priced per site or per sensor.
Is an MSSP responsible when an incident occurs?
No, an MSSP does not take over ultimate accountability. Under NIS2 and the Dutch Cybersecurity Act, your organisation’s management body remains responsible for the duty of care and the reporting obligation. The MSSP is responsible for meeting its contractual commitments and SLAs.
Does an MSSP itself fall under NIS2?
Yes, managed security service providers are listed in Annex I of NIS2 under the ICT service management sector. An MSSP of medium size or larger must therefore meet the duty of care and reporting obligations itself. Implementing Regulation (EU) 2024/2690 specifies the technical requirements for these providers.
Can a regular IT MSSP also monitor OT?
An IT-focused MSSP can only monitor OT properly if it understands industrial protocols, process risks and the arrangements with operations. Without that knowledge, false alarms or risky interventions on production systems follow. Ask for OT-specific tooling, references and experience with IEC 62443.
What is the difference between an MSSP and a SOC?
A SOC is the function or department that monitors and follows up on security alerts. An MSSP is an external party that delivers such a SOC as a service, often together with other security services. An organisation can therefore run its own SOC, engage an MSSP or combine both.
How do you limit the risk of an MSSP with access to your network?
You limit the risk of an MSSP with MFA, least privilege, separate accounts per analyst, full logging of all sessions and connections initiated from your side. Include security requirements, audit rights and notification arrangements in the contract. Periodically check whether access is still needed and revoke it immediately on termination.
📌 In summary
An MSSP delivers the continuous monitoring, expertise and scale that many organisations cannot build themselves. In OT this calls for passive monitoring, respect for process operations and clear agreements about authority. Under NIS2 and the Dutch Cybersecurity Act, the MSSP is both regulated itself and a supplier whose risk you must manage.
An MSSP is an external partner that manages and monitors your Cybersecurity, including OT and industrial networks; accountability for your security and your reporting obligation, however, always stays with you.