Managed Detection and Response for Networks: Service Breakdown

Managed Detection and Response (MDR) for networks is a contracted security service in which a third-party provider delivers continuous threat monitoring, detection, investigation, and active response across an organization's network infrastructure. This page covers how MDR services are structured, the operational phases involved, the scenarios in which they apply, and the boundaries that distinguish MDR from adjacent services such as managed SIEM or traditional network monitoring. Understanding these distinctions matters because miscategorizing the service type leads to coverage gaps that threat actors routinely exploit.

Definition and scope

MDR for networks is a managed security service that combines technology-layer detection tools with human analyst oversight to identify and contain threats within a customer's network environment. The defining characteristic is the response component: unlike passive alerting services, MDR providers take direct or coordinated action to contain, isolate, or remediate threats, typically within a defined response time window stated in the service-level agreement.

NIST's Cybersecurity Framework (CSF) organizes security capabilities across five functions — Identify, Protect, Detect, Respond, and Recover. MDR for networks operates primarily across the Detect and Respond functions, with ancillary activity in the Recover function when remediation guidance is included. This framework alignment is useful for scoping contracts: a service that covers only Detect is a managed monitoring service, not MDR.

Scope boundaries vary by provider but typically include:

1. Network traffic analysis — deep packet inspection and flow-level analysis across north-south and east-west traffic
2. Endpoint telemetry correlation — integrating endpoint detection signals with network-layer events
3. Identity and access anomaly detection — flagging abnormal authentication patterns within the network perimeter
4. Threat intelligence enrichment — matching observed indicators of compromise (IOCs) against vetted threat intelligence feeds
5. Active response actions — blocking IP addresses, isolating segments, revoking sessions, or escalating to the customer's incident response team

For organizations subject to federal cybersecurity requirements, CISA's Cybersecurity Advisory guidance frequently references continuous detection capabilities as baseline expectations for critical infrastructure operators. Aligning MDR scope to these advisories supports compliance documentation during audits.

How it works

MDR for networks operates through a structured operational cycle with discrete phases. The MITRE ATT&CK framework, maintained by The MITRE Corporation, is the predominant taxonomy MDR providers use to classify attacker techniques and map detection logic.

Phase 1 — Data collection and ingestion
Sensors, agents, and network taps forward telemetry to the provider's security operations platform. Traffic volumes on enterprise networks routinely reach tens of gigabits per second, requiring inline collection hardware or cloud-forwarded NetFlow records.

Phase 2 — Automated detection and triage
Machine learning models and rule-based logic process ingested data against known attack patterns. Detection rules are mapped to MITRE ATT&CK technique IDs (e.g., T1071 for Application Layer Protocol abuse), allowing providers to demonstrate coverage specificity rather than generic alerting.

Phase 3 — Human analyst investigation
Alerts above a defined confidence threshold escalate to a Security Operations Center (SOC) analyst for contextual review. The analyst validates whether an alert represents a true positive, a false positive, or a low-priority event requiring no action. This human review step is the primary differentiator between MDR and a fully automated SOAR-only deployment — a distinction the SANS Institute has documented in its security operations curriculum.

Phase 4 — Containment and response
Upon confirming a threat, the analyst executes a pre-authorized response playbook or coordinates with the customer's designated security contact. Response actions are constrained by the authorization scope defined in the contract.

Phase 5 — Reporting and feedback
Incident reports, dwell time metrics, and detection coverage summaries are delivered on a cadence defined in the SLA. These outputs feed the customer's broader network security services governance process and inform policy updates.

Common scenarios

MDR for networks addresses a specific class of operational situations that passive monitoring tools cannot resolve alone.

Ransomware lateral movement: Attackers who gain an initial foothold via phishing or a compromised VPN credential frequently move laterally across internal network segments before deploying ransomware. MDR providers detect anomalous SMB traffic patterns or unauthorized use of administrative protocols consistent with MITRE ATT&CK Lateral Movement tactics and can isolate affected segments before encryption begins.

Supply chain compromise: Threat actors targeting software supply chains inject malicious code that executes on customer networks after a legitimate software update. MDR telemetry detects unexpected outbound connections or unusual process behavior tied to trusted software, a detection challenge that perimeter firewalls alone cannot address. CISA has issued multiple advisories specifically covering supply chain detection requirements for federal contractors.

Insider threat and credential abuse: Anomalous access patterns — such as a service account querying database tables outside its normal operating hours — surface through behavioral baselining. This scenario is particularly relevant for organizations managing network services for healthcare or network services for government, where data sensitivity amplifies the consequence of undetected access.

Distributed Denial of Service (DDoS) amplification: Some MDR providers include network-layer volumetric attack detection and can trigger upstream filtering or coordinate with ISP-level mitigation, though this capability is not universal and must be verified against the specific contract scope.

Decision boundaries

Selecting MDR versus an adjacent service requires comparing service capability profiles across four dimensions.

MDR vs. managed SIEM: A managed SIEM aggregates and correlates log data and generates alerts, but the response function remains with the customer's internal team. MDR shifts response execution to the provider. Organizations with mature internal SOC teams may prefer managed SIEM; those without 24/7 internal analyst coverage are better served by MDR.

MDR vs. network monitoring: Network monitoring services track performance metrics — latency, packet loss, interface utilization — and alert on availability degradation. MDR tracks adversarial behavior. The two services address entirely different failure modes and are complementary rather than substitutable.

MDR vs. in-house SOC: Building an internal SOC capable of 24/7 network MDR coverage requires staffing a minimum of 6 to 8 analysts per shift rotation to maintain continuous coverage across three shifts, plus tooling, infrastructure, and threat intelligence subscriptions. For organizations without that baseline, contracted MDR delivers equivalent functional coverage at lower total cost. The CISA Cybersecurity Workforce initiative documents the ongoing SOC staffing shortage that makes self-build SOC strategies operationally risky for mid-sized organizations.

Organizations evaluating MDR alongside broader managed network services contracts should assess whether the MDR provider's response authorization model aligns with the organization's incident response policy — specifically, which response actions require customer pre-approval versus autonomous provider execution. This authorization boundary defines the practical speed of containment and is the most consequential contract term to negotiate.

References

• NIST Cybersecurity Framework (CSF)
• MITRE ATT&CK Framework
• CISA Cybersecurity Advisories
• CISA Cybersecurity Workforce Development
• SANS Institute — Security Operations Curriculum
• NIST SP 800-61 Rev 2 — Computer Security Incident Handling Guide