Managed Detection and Response (MDR), Managed Security Service Providers (MSSPs), and SIEM (Security Information and Event Management) represent three distinct approaches to security operations, each with different cost structures, staffing requirements, and outcomes. Gartner projects the managed security services market will reach USD 58.2 billion by 2028, yet 62% of mid-market organizations report confusion about which model best suits their needs (Forrester, 2024). The right choice depends on your organization's size, security maturity, compliance obligations, and in-house capabilities. This guide provides a comprehensive comparison to help you decide.
Key Takeaways
- SIEM is a technology platform that requires in-house staff to operate; MDR and MSSP are service models that include human expertise.
- MDR focuses on active threat detection and response; MSSPs focus on broader security management and monitoring.
- MDR typically costs EUR 5,000-20,000/month; MSSP EUR 3,000-15,000/month; SIEM EUR 100,000-500,000/year plus staffing.
- Organizations with limited security staff benefit most from MDR; mature teams benefit from SIEM with MSSP augmentation.
- Many organizations combine models: SIEM for visibility, MDR for detection, MSSP for perimeter management.
Understanding the Three Models
SIEM: The Technology Foundation
SIEM is a technology platform, not a service. It collects, normalizes, and correlates log data from across your environment to identify potential security incidents. Leading SIEM platforms include Splunk, Microsoft Sentinel, IBM QRadar, and Elastic Security.
A SIEM on its own does not detect or respond to threats. It requires trained analysts to write correlation rules, tune alert thresholds, investigate alerts, and take action. According to the Ponemon Institute's 2023 SIEM Effectiveness Study, organizations that deploy SIEM without dedicated analysts experience a 78% false positive rate, leading to alert fatigue and missed real threats.
SIEM provides unmatched data visibility and is essential for compliance, as frameworks like NIS2, PCI DSS, and ISO 27001 require centralized log management and retention. However, it demands significant investment in both technology and human capital.
MSSP: Broad Security Management
A Managed Security Service Provider delivers outsourced security operations, typically including firewall management, VPN administration, vulnerability scanning, intrusion detection, and log monitoring. MSSPs evolved from the traditional outsourcing model and focus on managing security infrastructure.
According to Gartner's 2024 Market Guide for Managed Security Services, MSSPs primarily provide alert notification rather than active response. The typical MSSP workflow involves monitoring your environment, identifying alerts, and escalating them to your internal team for investigation and remediation. This model works well when you have internal security staff who can act on escalations but need help with 24/7 coverage and infrastructure management.
MDR: Active Detection and Response
Managed Detection and Response is the most hands-on model. MDR providers deploy their own technology stack (typically EDR/XDR, SIEM, and SOAR), staff it with experienced threat hunters and analysts, and actively respond to threats on your behalf. The key differentiator is that MDR providers take action: they contain threats, isolate compromised systems, and remediate incidents rather than simply alerting your team.
Forrester's 2024 MDR Wave report found that MDR providers achieve a mean time to respond (MTTR) of under 30 minutes for critical threats, compared to 4-8 hours for MSSP escalation-based models. This speed is critical when dealing with ransomware that can encrypt an entire network in under 45 minutes (Splunk, 2024).
Comprehensive Comparison Table
| Feature | SIEM (Self-Managed) | MSSP | MDR |
|---|---|---|---|
| What it is | Technology platform | Outsourced security management | Active detection and response service |
| Primary focus | Log aggregation, correlation, compliance | Infrastructure monitoring, alert notification | Threat detection, hunting, active response |
| Staffing required | 3-8 FTE analysts minimum | 1-2 internal liaisons | 0-1 internal security contact |
| Response capability | Depends on your team | Alert and escalate | Contain, isolate, remediate |
| Annual cost (mid-market) | EUR 150,000-700,000 (license + staff) | EUR 36,000-180,000 | EUR 60,000-240,000 |
| Mean time to respond | Hours to days (varies) | 4-8 hours (escalation) | 15-30 minutes (direct) |
| Technology ownership | Customer owns and operates | Shared or customer-owned | Provider-owned and managed |
| Threat hunting | If staff has capacity | Rarely included | Proactive, included |
| MITRE ATT&CK coverage | Depends on rule development | Basic to moderate | Comprehensive (typically 80%+) |
| Compliance reporting | Excellent (full log retention) | Good (standard reports) | Good (incident-focused) |
| Best for | Large enterprises with mature SOC teams | Organizations needing infrastructure management | Organizations needing active threat defense |
Decision Framework: Choosing by Organization Profile
Small Businesses (Under 500 Employees)
Small organizations typically have zero to one dedicated security staff. Running a SIEM is impractical due to the expertise and time required. An MSSP can handle basic security hygiene (firewall, antivirus, patching), but for actual threat detection and response, MDR is the most effective choice. The Ponemon Institute found that small businesses using MDR reduced breach impact by 57% compared to those using traditional MSSP monitoring alone.
Recommendation: MDR as the primary service, potentially with MSSP for infrastructure management if internal IT is limited.
Mid-Market Organizations (500-5,000 Employees)
Mid-market organizations often have a small security team (2-5 people) that handles policy, compliance, and vendor management but lacks capacity for 24/7 threat monitoring. This is the segment where the MSSP vs MDR decision is most critical.
If your primary challenge is meeting NIS2 compliance requirements and maintaining security infrastructure, an MSSP with SOC capabilities may suffice. If you face advanced threat actors or operate in a high-risk sector (finance, healthcare, critical infrastructure), MDR provides the active response capability you need. Many mid-market organizations opt for a combined approach. Learn more about the SOCaaS model for mid-market businesses.
Recommendation: MDR for threat defense, supplemented with MSSP for infrastructure management if needed.
Large Enterprises (5,000+ Employees)
Large enterprises typically operate their own SIEM and have an internal SOC team. The question here is not whether to use SIEM but how to augment it. MDR can supplement an internal SOC by providing off-hours coverage, specialized threat hunting, or coverage for specific technology domains (cloud, OT/ICS). MSSPs can manage commodity security infrastructure, freeing the internal team for strategic work.
Recommendation: Internal SIEM + SOC as the foundation, with MDR for augmentation and MSSP for infrastructure management.
Market Size and Trends
The managed security market is experiencing significant growth across all three segments:
- SIEM market: USD 6.4 billion in 2024, projected USD 11.3 billion by 2029 (CAGR 12.1%), according to MarketsandMarkets. Cloud-native SIEM adoption is accelerating, with 45% of new deployments being cloud-based (Gartner, 2024).
- MSSP market: USD 31.5 billion in 2024, projected USD 52.9 billion by 2028 (CAGR 13.8%), per Allied Market Research. Growth driven by NIS2 and increasing compliance requirements across Europe.
- MDR market: USD 4.1 billion in 2024, projected USD 12.6 billion by 2029 (CAGR 25.1%), according to Mordor Intelligence. MDR is the fastest-growing segment as organizations prioritize outcomes over tools.
Gartner predicts that by 2027, 50% of organizations will use MDR services, up from approximately 30% in 2024. The analyst firm also notes a convergence trend: leading MSSPs are adding MDR capabilities, and MDR providers are expanding into broader managed security offerings.
When to Combine Models
In practice, many organizations use a combination of approaches. Common hybrid models include:
- SIEM + MDR: You own the SIEM for compliance and visibility; the MDR provider adds threat hunting and active response. This works well for organizations that need long-term log retention for regulatory purposes but want expert threat detection.
- MSSP + MDR: The MSSP manages your security infrastructure (firewalls, VPN, email security); the MDR provider handles threat detection and response. This is ideal for organizations with limited internal IT capacity.
- All three: Large enterprises may run an internal SIEM, use an MSSP for infrastructure management, and engage an MDR provider for advanced threat hunting and incident response. While more expensive, this layered approach provides the deepest defense.
Key Questions to Ask Providers
Regardless of which model you choose, these questions help evaluate providers effectively:
- What is your MTTR for critical incidents? Get specific SLA numbers, not vague promises. Best-in-class MDR providers guarantee under 15 minutes; MSSPs typically commit to 4-hour escalation.
- What is your MITRE ATT&CK technique coverage? This reveals detection breadth. Ask for their coverage mapped to the framework.
- How do you handle false positives? A provider drowning you in alerts is worse than no provider. Ask about their false positive rate and tuning processes.
- What happens when you detect a threat? The answer reveals whether they alert and escalate (MSSP model) or contain and remediate (MDR model).
- How do you support NIS2 compliance? European organizations need providers familiar with NIS2 Article 21 security measures and Article 23 incident reporting timelines. See our incident response plan framework for NIS2 alignment.
Orizon's Oversight service combines MDR capabilities with comprehensive security monitoring, delivering active threat detection and response specifically designed for European organizations navigating NIS2 and GDPR requirements.