Can MDR replace SIEM?

MDR can replace the threat detection and investigation functions of a SIEM, but not necessarily its compliance and log retention capabilities. If your primary SIEM use case is threat detection, MDR often delivers better outcomes at lower cost. If you need long-term log retention for regulatory compliance, you may still need a SIEM or log management platform alongside MDR.

Is MDR more expensive than an MSSP?

MDR typically costs more per month than a basic MSSP engagement, but delivers significantly more value through active response and advanced detection. When you factor in the internal resources needed to investigate and remediate the alerts an MSSP forwards, MDR often provides better total cost of ownership and superior security outcomes.

Can I use MDR and MSSP together?

Yes, some organizations use an MSSP for operational tasks like firewall management and vulnerability scanning while using MDR for advanced threat detection and response. This hybrid approach works well when the MSSP and MDR provider have clear scope boundaries and integration points to avoid gaps or duplication.

How long does it take to deploy MDR?

Most MDR providers can achieve initial deployment in 1-4 weeks, depending on environment complexity. Endpoint agent deployment is typically fastest, followed by cloud and network sensor integration. Full tuning and baseline establishment usually takes an additional 2-4 weeks, during which the provider learns your environment's normal patterns.

What size company needs MDR?

MDR is valuable for organizations of all sizes that lack the internal resources to operate a 24/7 security operation. Mid-market companies with 500-5,000 employees are the primary MDR adopters, but small companies needing enterprise-grade detection and large enterprises supplementing internal SOCs also benefit from MDR services.

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MDR vs MSSP vs SIEM

MDR vs. MSSP vs. SIEM: Key Differences Explained

MDR, MSSP, and SIEM are three distinct approaches to security operations. This comparison explains what each delivers, where they overlap, and how to choose the right model for your organization.

Updated February 15, 20268 min read

MDR vs. MSSP vs. SIEM: Overview

Security teams face a critical decision when building their detection and response capabilities: invest in SIEM technology, outsource to a Managed Security Service Provider, or adopt Managed Detection and Response. Each approach addresses security operations differently, and the right choice depends on your organization's maturity, budget, internal expertise, and desired outcomes. SIEM is a technology platform that aggregates and correlates security data. An MSSP is a service provider that manages security infrastructure and monitors alerts. MDR is an outcome-focused service that combines technology, threat intelligence, and human expertise to detect and respond to threats. These categories increasingly overlap as the market evolves, but understanding their core differences helps organizations make informed investments. Many mature organizations combine multiple approaches, using SIEM for compliance and log management while layering MDR for advanced detection and response.

What Is SIEM?

Security Information and Event Management is a technology category that collects, normalizes, and correlates log data from across your IT environment. SIEM platforms ingest data from firewalls, endpoints, servers, applications, cloud services, and identity providers to provide centralized visibility and alerting. Core SIEM capabilities include real-time event correlation, threat detection rules, compliance reporting, log retention, and forensic search. Modern SIEM platforms have evolved to include User and Entity Behavior Analytics and security orchestration features. However, SIEM is fundamentally a tool, not a service. It requires skilled analysts to write detection rules, tune alert thresholds, investigate findings, and respond to confirmed threats. Organizations that deploy SIEM without adequate staffing often experience alert fatigue, with thousands of daily alerts and insufficient resources to investigate them. The total cost of ownership extends well beyond license fees to include staffing, training, integration, and ongoing tuning, often making SIEM the most expensive option when fully accounted.

What Is an MSSP?

A Managed Security Service Provider delivers outsourced monitoring and management of security infrastructure. Traditional MSSPs operate security operations centers that monitor customer environments, typically using the customer's own SIEM or security tools. MSSPs excel at operational tasks like firewall management, vulnerability scanning, log monitoring, and basic alert triage. They provide 24/7 coverage that most organizations cannot staff internally and offer cost efficiencies through shared infrastructure and multi-tenant operations. However, traditional MSSPs have well-documented limitations. Their operating model is often alert-centric rather than threat-centric, meaning they forward alerts with basic context rather than performing deep investigation. Response actions are frequently limited to notification, requiring your internal team to investigate and remediate. Service quality varies significantly between providers, and many MSSPs struggle with the same alert fatigue challenges their customers face, just at a larger scale. The MSSP model works well for organizations seeking operational coverage and compliance monitoring but may fall short for advanced threat detection.

What Is MDR?

Managed Detection and Response is a service category that delivers threat detection, investigation, and active response as a managed outcome. Unlike traditional MSSPs that primarily monitor and notify, MDR providers take direct action to contain and remediate threats on behalf of their customers. MDR services typically deploy their own technology stack, including endpoint detection and response agents, network sensors, and cloud integrations, reducing the customer's technology burden. The service is staffed by experienced threat hunters and incident responders who proactively search for threats that evade automated detection. When threats are confirmed, MDR analysts execute containment actions like isolating compromised endpoints, disabling accounts, and blocking malicious network connections. This active response capability is the defining difference between MDR and traditional managed security services. MDR providers also deliver regular threat hunting reports, security posture recommendations, and strategic guidance that help customers continuously improve their security maturity beyond just monitoring.

How to Choose the Right Approach

Choosing between SIEM, MSSP, and MDR depends on several factors. Organizations with mature security teams and compliance-driven log retention requirements often benefit from SIEM as the foundation, potentially supplemented by MDR for advanced detection. Companies seeking cost-effective 24/7 monitoring with an internal team handling investigations may find an MSSP appropriate, particularly if the primary need is infrastructure management and compliance reporting. Organizations that want detection and response outcomes without building a large internal security operation should prioritize MDR, especially if they lack the analysts needed to operate a SIEM effectively. Budget is a practical consideration, but total cost of ownership matters more than sticker price. A SIEM that costs less to license but requires five additional analysts is more expensive than an MDR service that includes those capabilities. Consider your desired outcome: do you need a tool, operational coverage, or threat detection and response results? The answer to that question typically points to the right model for your organization.

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