What is the difference between MDR and MSSP?

A traditional MSSP monitors and alerts — alerts are delivered to your team, which is responsible for investigation and response. An MDR provider investigates and responds. When SENTRY identifies a potential threat, analysts investigate it, confirm or dismiss it, and if confirmed, execute active containment — host isolation, credential invalidation, blocking rules — without requiring your team to act first. The difference determines who bears the operational burden when a threat fires at 2 AM.

MDR vs. MSSP: What the Difference Means for Your Risk Posture

MDR and MSSP are not the same service. The distinction — who investigates and who responds when a threat is confirmed — determines whether your security program closes the gap between detection and containment, or whether that gap remains your organization’s operational burden. This page explains the difference, what it costs you in risk terms, and where Armorstack fits as a Managed Intelligence Provider.

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The Core Distinction: Alert-and-Notify vs. Investigate-and-Respond

The managed security services market has fragmented into a spectrum of offerings, and the terminology does not always map cleanly to operational reality. The most consequential difference between MDR and a traditional MSSP is not the technology underneath either program — it is what happens after an alert fires.

How a Traditional MSSP Operates

A managed security services provider (MSSP) typically provides monitoring and alerting. The MSSP’s SOC watches your environment, applies detection rules to your log data, and sends alerts to your team when something looks suspicious. The investigation and response work — determining whether the alert represents a real threat, containing the affected systems, remediating the compromise, and producing the incident documentation — remains with your organization. Your team receives the alert and carries the operational burden from that point forward.
This model has legitimate use cases. Organizations with a sufficiently staffed internal security team can effectively use MSSP alerting as a force multiplier: the MSSP provides coverage hours that the internal team cannot staff, and the internal team handles the investigation and response during business hours. The model breaks down when the internal team is not sufficiently staffed to receive and act on alerts in a time-critical way — which describes most mid-market organizations.

How MDR Operates

Managed Detection and Response providers investigate and respond. When the detection platform surfaces an alert, MDR analysts investigate: they review correlated events across log sources, apply threat intelligence context, examine the alert in the context of your environment’s normal behavior, and make a determination. If the investigation confirms a threat, the MDR provider executes active response — isolating affected hosts, invalidating compromised credentials, applying blocking rules, and engaging your team with a real-time incident brief and documented response timeline. The investigation and containment burden does not transfer back to your organization.
The response time advantage is material. The average time between initial access and lateral movement in enterprise environments is measured in hours, not days — published incident response data from Mandiant and CrowdStrike consistently shows this compression. An alert that reaches your team’s inbox at 11 PM on a Friday and is triaged at 9 AM Monday has given an adversary a 58-hour operational window. An MDR program that investigates that alert in real time and executes containment within the hour closes most of that window. The difference between those two outcomes is not the detection — it is who responds, and when.

For the full program architecture of how SENTRY MDR operates, see Armorstack SENTRY Managed Detection and Response. For what SOC-as-a-Service delivers as a program, see SOC-as-a-Service: What the Program Delivers.

MDR vs. MSSP: A Direct Comparison

Capability	Traditional MSSP	MDR Provider	Armorstack SENTRY (Managed Intelligence Provider)
24/7 monitoring	Yes — log monitoring and alert generation	Yes — monitoring plus analyst investigation	Yes — 24/7 SOC staffed by 100+ security professionals
Alert triage and investigation	Limited — alerts delivered to your team for investigation	Yes — analysts investigate before escalating	Yes — full investigation with threat intelligence enrichment and environment context
Active response (containment)	No — response is your organization’s responsibility	Yes — host isolation, credential invalidation, blocking rules executed by the provider	Yes — active containment executed and documented; your team engaged in real time
Proactive threat hunting	Rarely — MSSP programs are reactive; hunting is typically a separate engagement	Included in mature MDR programs	Yes — hypothesis-driven hunting on defined frequency; documented for compliance evidence
Compliance evidence generation	Limited — alert logs available; structured compliance evidence packages typically require additional effort	Varies by provider	Yes — built into program workflow for HIPAA, PCI-DSS, CMMC, NIST CSF, GLBA, SOC 2
Incident response	Not included — typically a separate retainer or engagement	Included in most MDR programs	Yes — included; forensic analysis, regulatory notification support, post-incident review
Cyber-physical correlation	No	Rarely — most MDR providers are network-only	Yes — CITADEL physical security telemetry (access control, video analytics) feeds the same SOC
AI security observability	No	Emerging — few providers include this natively	Yes — shadow AI detection, prompt injection monitoring, anomalous model behavior included
Internal team burden post-alert	High — investigation, response, and documentation are your team’s responsibility	Low — investigation and containment handled by the MDR provider	Low — full response handled and documented; your team receives brief and participates in recovery
Appropriate for organizations with	Sufficient internal security staff to investigate and respond to alerts in real time, including off-hours	Limited internal security staff who need the investigation and response burden handled externally	Mid-market regulated organizations that need a complete, converged, compliance-documented security operations program

The Risk Posture Implication: Why the Distinction Matters More Than the Label

The Detection-to-Containment Gap Is Your Primary Risk Variable

In cybersecurity incident analysis, dwell time — the period between initial access and detection — is a primary predictor of breach impact. A related but equally important variable is the gap between detection and containment. An alert that fires and is actioned within the hour produces a materially different outcome than an alert that fires, waits in a queue until the next business day, and is investigated after an adversary has had 12 or 18 hours to move laterally, escalate privileges, and establish persistence.
Under an MSSP model, the detection-to-containment gap is determined by your internal team’s capacity and schedule. If your team goes home at 5 PM, the gap is at minimum the overnight and weekend hours. Under an MDR model, the gap is determined by the provider’s response SLA — typically measured in minutes for confirmed threats, not hours. The risk reduction from that SLA difference is real, measurable, and directly relevant to your cyber insurance profile and regulatory exposure.

Regulatory Implications: Who Owns the Response?

For organizations operating under HIPAA, CMMC, or PCI-DSS, the distinction between detection and response is not merely operational — it is regulatory. HIPAA’s Security Incident Procedures standard (§ 164.308(a)(6)) requires documented procedures to respond to suspected or known security incidents. CMMC 2.0 IR.2.092 requires tracking, documenting, and reporting incidents. These requirements do not end at detection. They require response capability and documentation that demonstrates that response capability was exercised.
Under an MSSP model, your organization is responsible for demonstrating that response capability. Under an MDR model with active response, the provider’s incident documentation — produced in real time, structured for the relevant compliance framework — is part of the evidence package. For organizations facing C3PAO assessments, OCR investigations, or PCI-DSS audits, that documentation is not a nice-to-have. It is the evidence that the control worked. See Armorstack’s full CMMC readiness program for the complete compliance context.

Where Armorstack Fits: Managed Intelligence Provider

Armorstack is not an MSSP. Armorstack is a Managed Intelligence Provider — a designation that reflects a fundamentally different program model. The SENTRY program is built on the MDR operating model: SENTRY investigates and responds, rather than alerting your team and waiting. But SENTRY extends beyond the MDR model in two directions that most MDR providers do not cover.
First, SENTRY operates across cyber and physical security simultaneously. The converged SENTRY + CITADEL program means that physical access events, video analytics anomalies, and building system status feed the same SOC monitoring your network. An adversary who badges into your facility after hours and then attempts an unusual authentication is detectable as a correlated threat in a way that no network-only program can surface. Second, SENTRY incorporates AI security observability — monitoring for shadow AI adoption, prompt injection attempts, and anomalous model behavior — as part of the standard program, because the AI threat surface your organization is accumulating is already part of the attack surface that needs monitoring. For more on AI security, see Armorstack AI Security.
The Managed Intelligence Provider designation means the program is designed around outcomes — confirmed threat containment, compliance evidence, and a documented security posture that improves over time — not around the number of alerts processed or the number of tools deployed.

How to Evaluate Whether You Have MDR or MSSP Today

Organizations with an existing managed security engagement should be able to answer the following questions about their current provider. The answers determine whether the program is operating as MDR or MSSP, regardless of how it is labeled in the contract.

When an alert fires at 2 AM, what does your provider do? If the answer is “sends us an email or ticket,” the program is MSSP. If the answer is “investigates and calls us if it is confirmed,” the program is MDR.
Who makes the determination that an alert is a genuine threat vs. a false positive? If that determination falls to your team, the program is MSSP.
If a threat is confirmed, who isolates the affected system? If the answer is “our team, after we receive the alert,” the program is MSSP. If the answer is “the provider executes isolation and notifies us in parallel,” the program is MDR.
Does your provider generate compliance-structured incident documentation? If you are assembling evidence packages manually before audits from raw SIEM exports, the program does not include compliance evidence generation as a delivered capability.
Does your provider conduct proactive threat hunting? If hunting is not on a scheduled cadence with documented hypotheses, it is likely not happening systematically.

For a scoped assessment of your current program’s coverage gaps and a comparison against the SENTRY MDR program, contact Armorstack. For more on how MDR is priced and scoped, see MDR Pricing: How Managed Detection and Response Is Priced.

Frequently Asked Questions About MDR vs. MSSP

Can an MSSP become an MDR provider by adding more analysts?

Adding analyst headcount is a necessary but not sufficient condition. The distinction between MSSP and MDR is as much about operational model as staffing level. An MDR program requires investigation workflows, active response playbooks, documented containment procedures, and integration between the detection platform and the response capability. An MSSP that adds analysts without restructuring the operational model — particularly the decision authority to execute active response rather than alert and wait — is a larger MSSP, not an MDR provider. When evaluating providers that claim to offer MDR, the operational questions above are the right test: what specifically happens at 2 AM, who makes the threat determination, and who executes containment.

Does our organization need MDR if we already have an EDR platform?

An EDR (endpoint detection and response) platform is a detection and response tool. MDR is a program built around human analysts who operate detection tools — which may include your EDR — and execute response on your behalf. An EDR platform that generates alerts into a console that nobody is reviewing around the clock is not a detection and response program. Most mid-market organizations that have deployed EDR platforms have not deployed them with the 24/7 analyst coverage required to operate them as a genuine detection and response capability. SENTRY can operate alongside your existing EDR, integrating its telemetry into the managed SIEM and applying analyst coverage to the alert stream that your team currently cannot staff continuously.

Is MDR more expensive than MSSP?

MDR programs typically carry a higher program cost than basic MSSP monitoring, because they include investigation and response labor that MSSP programs do not. The relevant economic comparison is not MDR cost vs. MSSP cost — it is MDR cost vs. MSSP cost plus the cost of the internal team required to investigate and respond to MSSP alerts, plus the cost of the incidents that occur during the detection-to-containment gap that the MSSP model leaves open. For most mid-market organizations, that full comparison shifts the economics toward MDR. For more on cost drivers, see SOC-as-a-Service Pricing: What Drives the Cost.

What is a Managed Intelligence Provider, and how is it different from an MDR provider?

Armorstack’s designation as a Managed Intelligence Provider reflects a program model that extends beyond the standard MDR scope in two directions. First, SENTRY operates across both cyber and physical security through the converged SENTRY + CITADEL program — physical access control, video analytics, and building system telemetry feed the same SOC monitoring the network. Second, SENTRY incorporates AI security observability — monitoring for shadow AI, prompt injection attempts, and anomalous AI model behavior — as part of the standard program, not as a future add-on. The Managed Intelligence Provider model is outcome-oriented: the program is designed around confirmed threat containment, compliance evidence, and a measurable reduction in risk posture, not around the number of tools deployed or alerts processed.

How does Armorstack position itself relative to MSSP providers in our market?

Armorstack is not an MSSP, and does not compete primarily on that basis. Armorstack SENTRY competes against both standalone MDR providers (who cover cyber but not physical, and who typically do not include AI security observability) and full MSSP programs (where the investigation and response model leaves the operational burden with the client). The SENTRY differentiation is the converged program: cyber detection and response, physical security correlation, AI security observability, and compliance evidence generation delivered by a single Managed Intelligence Provider under one engagement, with one SLA, and one point of accountability for outcomes. For organizations in regulated industries that need a complete security operations program rather than a tool or a monitoring feed, SENTRY is built for that requirement.

What happens to our current MSSP contract if we move to SENTRY MDR?

That depends on your current contract terms — exit provisions, notice periods, and auto-renewal clauses vary by provider. Armorstack’s scoped assessment process includes a contract review component that helps organizations understand their transition timeline and structure the SENTRY engagement to minimize coverage gaps during the transition period. The 90-Day Proof is one option for organizations with existing MSSP contracts: it deploys SENTRY in parallel with the existing engagement, allowing you to validate MDR outcomes before the MSSP contract reaches its renewal point. Contact Armorstack to discuss your transition options.

The Program Your Organization Needs Is Determined by Who Responds When It Counts

Armorstack SENTRY operates as a Managed Intelligence Provider — not an MSSP. SENTRY investigates, responds, and documents outcomes. The 90-Day Proof deploys the full program in your environment and delivers measurable evidence of the difference before you commit to a long-term engagement.