# What is a Managed Security Service Provider (MSSP)?

> A managed security service provider is an external organization that delivers ongoing cybersecurity functions for a customer under a service agreement.

- Canonical URL: https://yellowcube.eu/glossary/managed-security-service-provider/
- Publisher: Yellow Cube
- Language: en
- Contact: hello@yellowcube.eu

## Content

Services can include operating security controls, monitoring logs and alerts, managing vulnerabilities, administering firewalls or identities, supporting compliance, and assisting with incidents. Scope varies widely: the term describes a provider relationship, not a standard package or level of assurance.

Using an MSSP changes who performs work but does not transfer the customer’s accountability for risk. The parties need an explicit responsibility model covering assets and environments in scope, access, data handling, detection and escalation duties, authority to take response actions, reporting, evidence retention, subcontractors, and exit arrangements. The provider’s own security and resilience matter because privileged access and multi-customer infrastructure can create concentrated risk.

### Key points

- **Define the service:** Specify coverage hours, technologies, telemetry, use cases, response targets, exclusions, customer dependencies, and measurable service outcomes rather than relying on a service label.
- **Control provider access:** Apply least privilege, strong authentication, separate administrative identities, session logging, rapid revocation, and customer approval for consequential changes.
- **Plan for incidents and exit:** Agree on notification paths, evidence ownership, joint exercises, provider-compromise procedures, data portability, transition support, and secure deletion at contract end.
- **Important limitation:** An MSSP cannot protect assets it cannot see or control, and outsourcing can introduce dependency, concentration, and supply-chain risks. The customer still needs informed ownership and a way to verify performance.

### Related terms

[Managed detection and response (MDR)](<https://yellowcube.eu/glossary/managed-detection-and-response/>) · [Security operations center as a service (SOCaaS)](<https://yellowcube.eu/glossary/security-operations-center-as-a-service/>) · [Service-level agreement (SLA)](<https://yellowcube.eu/glossary/service-level-agreement/>) · [Third-party cyber risk](<https://yellowcube.eu/glossary/third-party-cyber-risk/>) · [Shared responsibility model](<https://yellowcube.eu/glossary/shared-responsibility-model/>) · [Managed extended detection and response (MXDR)](<https://yellowcube.eu/glossary/managed-extended-detection-and-response/>)

### Sources

[NIST SP 800-61 Rev. 3](https://csrc.nist.gov/pubs/sp/800/61/r3/final) · [ENISA Managed Security Services Market Analysis](https://www.enisa.europa.eu/publications/managed-security-services-market-analysis) · [CISA joint advisory: Protecting Against Cyber Threats to Managed Service Providers and their Customers](https://www.cisa.gov/sites/default/files/publications/AA22-131A_Protecting_Against_Cyber_Threats_to_MSPs_and_their_Customers.pdf)

## Attribution and scope

This Markdown representation is generated from the same approved content records as the canonical HTML page. Cite the canonical URL above when referencing this material. Product and service descriptions are informational; confirm project-specific requirements with Yellow Cube.