SIEM vs SOAR: Where Detection Ends and Response Begins

A SIEM collects and retains security telemetry, applies detection rules, correlates related alerts and gives analysts a case in which to investigate. A SOAR executes an ordered response process across tools, with retries, failure policies and approval gates where consequence requires them.

The handoff occurs when a detection has enough context and priority to require action. The SIEM side should preserve why the signal exists. The SOAR side should preserve who or what authorised the response and whether each action succeeded.

Nexus Sentinel contains both capabilities in one sovereign product. That does not make the terms interchangeable. It removes the integration seam between the investigation record and the runbook that acts on it.

Collection normalises telemetry from endpoints, infrastructure, applications and security controls. Detection rules identify conditions of interest. Correlation evaluates thresholds and windows, groups related alerts and suppresses repeated firing of the same situation.

Investigation adds observables, tasks, ownership, comments and prior context to a case. MITRE ATT&CK mappings help detection engineers understand which tactics and techniques have rules associated with them and where gaps remain.

The SIEM output is not merely an alert. It is an investigated situation with enough context to decide whether and how to respond.

A response runbook expresses the ordered actions that follow a case or signal. It can enrich the case, notify responders, call endpoint or request-layer controls, update an external system and write the outcome back.

Each action should define timeout, retry and failure behaviour. Approval can be attached to the specific action that carries operational or legal consequence. Low-risk enrichment may run automatically while containment waits for a named authoriser.

The SOAR output is a response history: actions attempted, approvals, target responses and the final state of the runbook.

When SIEM and SOAR are separate, the response layer may receive only a thin alert payload. Analysts and automation then rebuild asset ownership, related events, severity and prior case context through additional calls. Failures produce another set of logs to reconcile.

In Sentinel, detection, correlation, cases and runbooks share identity, context and audit. A response can be traced back to the exact rule and correlated signal that justified it. Its result returns to the same case.

This does not mean every detection should launch a runbook. Policy and investigation still determine whether the situation is benign, needs more evidence or warrants action.

Ask how repeated alerts become one signal, how a signal becomes a case, and what context crosses into the response. Ask whether runbook steps expose retries and partial completion, and whether approval applies per action rather than to the entire product.

Also ask where telemetry, cases and response history live. Sentinel is self-hosted in the customer estate, including air-gapped environments where required, so operation does not depend on sending security data to a vendor runtime.

Finally, ask whether detection content is readable and portable. Sentinel uses Sigma rules and maps coverage to MITRE ATT&CK. Those mappings support engineering and review. They are not certification.