Cloud & Infrastructure
Microsoft Sentinel: SIEM Made Simple for Mid-Market
17 March 2026 · 0x1m3 · 4 min read
Security Information and Event Management (SIEM) used to be enterprise-only technology. The infrastructure costs, staffing requirements, and complexity of traditional SIEM platforms kept mid-market organisations on the outside looking in.
Microsoft Sentinel changes that equation.
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What Is Microsoft Sentinel?
Sentinel is Microsoft's cloud-native SIEM and Security Orchestration, Automation, and Response (SOAR) platform. It collects security data from across your environment — endpoints, identity providers, cloud services, network devices — and uses analytics and automation to detect and respond to threats.
The critical difference from traditional SIEM: there is no infrastructure to deploy or maintain. No servers. No storage arrays. No database tuning. Sentinel runs entirely in Azure, scales automatically, and bills based on data ingestion volume.
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Why Mid-Market Organisations Should Pay Attention
Three factors make Sentinel relevant for mid-market right now.
1. No Infrastructure Overhead
Traditional SIEM platforms require dedicated servers, storage capacity planning, and skilled engineers to keep the platform running. For a mid-market organisation with a small IT team, that overhead is unsustainable. Sentinel eliminates it. Your team focuses on security outcomes, not platform maintenance.
2. Deep M365 Integration
If your organisation runs Microsoft 365, Sentinel connects natively to the entire Defender suite — Defender for Endpoint, Defender for Office 365, Defender for Identity, and Defender for Cloud Apps. These connectors are built-in and free of ingestion charges for many M365 data sources.
This means your existing Microsoft investment feeds directly into your SIEM without additional data connectors, agents, or parsing rules. For organisations already paying for M365 E3 or E5, Sentinel extends the value of that licensing.
3. Promotional Pricing Through June 2026
Microsoft currently offers a 50GB per day commitment tier with promotional pricing. Organisations that commit before June 2026 lock in those rates until March 2027. For mid-market environments generating moderate log volumes, this pricing tier makes Sentinel financially viable where traditional SIEM would not be.
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What Sentinel Does Well
Automated threat detection. Sentinel uses built-in analytics rules and machine learning to identify suspicious patterns across your environment. Impossible travel sign-ins, brute force attempts, data exfiltration patterns — these detections come pre-configured and start working immediately.
Incident correlation. Instead of presenting thousands of individual alerts, Sentinel groups related alerts into incidents. A compromised user account triggering alerts across email, endpoint, and cloud applications appears as a single incident with full context.
Automated response with playbooks. SOAR capabilities let you automate common response actions. Block a user account, isolate an endpoint, send a Teams notification to the security team — all triggered automatically based on incident type and severity.
Workbooks and dashboards. Pre-built and custom dashboards provide visibility into your security posture. Compliance reporting, threat landscape overviews, and operational metrics — all accessible from the Azure portal.
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Sentinel vs Splunk: A Brief Comparison
OAS deploys both Microsoft Sentinel and Splunk. They serve different use cases.
Splunk Enterprise Security is the enterprise-depth option. It excels in large-scale environments with diverse data sources, complex correlation rules, and mature Security Operations Centre (SOC) workflows. Splunk's search processing language (SPL) offers unmatched query flexibility. The latest Enterprise Security 8.2 release adds AI-assisted playbook authoring and enhanced User and Entity Behaviour Analytics (UEBA).
Sentinel is the M365 ecosystem option. It works best when Microsoft 365 and Azure are your primary platforms. The native integrations reduce deployment complexity and ongoing maintenance. For mid-market organisations without a dedicated SOC team, Sentinel's built-in automation handles much of what Splunk requires manual configuration to achieve.
| Factor | Microsoft Sentinel | Splunk |
|---|---|---|
| Best for | M365-heavy environments | Large-scale, multi-vendor environments |
| Infrastructure | Cloud-native (zero) | Cloud or on-premises |
| Data connectors | 200+ (M365 free ingestion) | 2,500+ |
| Query language | KQL (Kusto) | SPL |
| Automation | Built-in SOAR playbooks | SOAR (separate module) |
| Learning curve | Moderate | Steep |
| Pricing model | Per GB ingested | Per GB indexed |
The choice is not either/or. Some organisations run Sentinel for M365 telemetry and Splunk for broader infrastructure monitoring. OAS designs the architecture that fits your data sources and team capabilities.
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Getting Started with Sentinel
Deploying Sentinel follows a structured process:
1. Enable Sentinel on an Azure Log Analytics workspace 2. Connect data sources — start with M365 and Entra ID connectors 3. Activate analytics rules — enable built-in detections relevant to your environment 4. Configure automation — set up playbooks for common incident types 5. Build dashboards — create workbooks for your security and compliance reporting needs
OAS handles this deployment from start to finish. We configure the workspace, connect your data sources, tune analytics rules to reduce false positives, and train your team on incident response workflows.
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Sentinel makes enterprise SIEM accessible for mid-market. OAS configures it to work with your M365 stack.