Microsoft Sentinel: Enterprise SIEM & Security Operations

Microsoft Sentinel is a cloud-native SIEM (Security Information and Event Management) and SOAR (Security Orchestration, Automation, and Response) platform built on Azure. It collects security data at cloud scale from users, devices, applications, and infrastructure across on-premises and multi-cloud environments using 300+ built-in data connectors. Sentinel uses KQL (Kusto Query Language) analytics rules and machine learning to detect threats, correlates alerts into incidents, and automates response through Logic Apps playbooks. It sits on top of Azure Log Analytics workspaces and leverages Azure Monitor for data ingestion and storage. EPC Group deploys Sentinel for enterprises in healthcare, finance, and government as the central security operations platform.

Microsoft Sentinel uses a pay-as-you-go pricing model based on data ingestion volume. The primary cost is per GB ingested into the Log Analytics workspace: approximately $2.46 per GB/day for pay-as-you-go, with commitment tiers offering 15-50% discounts (100 GB/day tier at ~$1.96/GB, 500 GB/day tier at ~$1.54/GB). A typical mid-size enterprise ingesting 10-30 GB/day pays $2,000-$8,000 per month. Large enterprises ingesting 100+ GB/day pay $15,000-$40,000 per month. Microsoft 365 E5 security logs (Office 365, Azure AD sign-in, audit) are ingested free of charge. Free data sources also include Azure Activity logs and Office 365 audit logs. EPC Group optimizes Sentinel costs by 30-50% through log tiering, data collection rules, basic logs vs analytics logs, and archive tier strategies.

Microsoft Sentinel and Splunk are both enterprise SIEM platforms but differ significantly. Sentinel is cloud-native (no infrastructure to manage), uses consumption-based pricing (pay per GB ingested), includes native integration with Microsoft 365 and Azure (free data connectors and bi-directional response), provides built-in SOAR via Logic Apps at no additional license cost, and offers MITRE ATT&CK coverage mapping out of the box. Splunk requires on-premises or cloud infrastructure, charges per daily indexing volume (typically more expensive at scale), requires separate SOAR licensing (Splunk SOAR), and needs custom integrations for Microsoft data sources. Sentinel excels for Microsoft-heavy environments; Splunk excels for heterogeneous environments with deep on-premises legacy systems. EPC Group recommends Sentinel for enterprises with 50%+ Microsoft stack adoption.

Microsoft Sentinel supports 300+ data connectors across four categories. First-party Microsoft connectors include Microsoft 365, Azure AD/Entra ID, Microsoft Defender XDR, Defender for Cloud, Defender for IoT, Azure Activity, Azure Firewall, and Azure WAF — most with one-click setup. Third-party connectors include Palo Alto, Cisco ASA, Fortinet, CrowdStrike, AWS CloudTrail, GCP, Okta, Zscaler, and ServiceNow. Common Event Format (CEF) and Syslog connectors handle any device that outputs standard log formats. Custom connectors can be built using the Log Analytics API, Azure Functions, or Logic Apps for proprietary data sources. EPC Group typically connects 15-30 data sources per enterprise Sentinel deployment.

Sentinel analytics rules are the detection engine that identifies threats from ingested data. There are four types: Scheduled rules run KQL queries at defined intervals (every 5 minutes to every 24 hours) to detect patterns like impossible travel, brute force attempts, or data exfiltration. NRT (Near Real-Time) rules execute within 1-minute latency for critical detections like ransomware execution. Microsoft Security rules automatically create incidents from alerts generated by other Microsoft security products (Defender XDR, Defender for Cloud). Fusion rules use multi-stage ML models to correlate low-fidelity alerts across data sources into high-confidence incidents. Sentinel includes 400+ pre-built analytics rule templates mapped to MITRE ATT&CK. EPC Group customizes and tunes these rules to reduce false positive rates by 60-80% while maintaining detection coverage.

SOAR (Security Orchestration, Automation, and Response) in Sentinel uses Azure Logic Apps to automate incident response workflows. When an analytics rule triggers an incident, automation rules evaluate the incident and can automatically run playbooks — Logic Apps workflows that take action. Common playbooks include: enriching incidents with threat intelligence lookups and user details, isolating compromised devices via Defender for Endpoint API, disabling user accounts in Entra ID, blocking malicious IPs in Azure Firewall, sending Teams/Slack notifications to the SOC, creating ServiceNow tickets for incident tracking, and running containment actions across multiple security tools simultaneously. Sentinel includes 200+ pre-built playbook templates. EPC Group typically deploys 15-25 custom playbooks per enterprise, automating 40-60% of tier-1 SOC tasks and reducing mean time to respond (MTTR) from hours to minutes.

MITRE ATT&CK is a knowledge base of adversary tactics, techniques, and procedures (TTPs) used by real-world threat actors. Microsoft Sentinel maps its analytics rules and detections directly to the MITRE ATT&CK framework. The Sentinel MITRE ATT&CK blade provides a visual matrix showing which tactics and techniques your current analytics rules detect — and where gaps exist. Sentinel covers 14 MITRE ATT&CK tactics: Reconnaissance, Resource Development, Initial Access, Execution, Persistence, Privilege Escalation, Defense Evasion, Credential Access, Discovery, Lateral Movement, Collection, Command and Control, Exfiltration, and Impact. With all built-in rules enabled, Sentinel covers approximately 200+ MITRE ATT&CK techniques. EPC Group uses the MITRE ATT&CK coverage matrix to identify detection gaps and prioritize custom rule development based on the most relevant threat actors for each industry.

A typical enterprise Microsoft Sentinel implementation takes 8 to 16 weeks across four phases. Phase 1 (Weeks 1-2) covers architecture design: workspace strategy, data collection planning, role-based access, and cost estimation. Phase 2 (Weeks 3-6) deploys data connectors: Microsoft first-party sources, network appliances via CEF/Syslog, cloud platforms, and identity providers. Phase 3 (Weeks 7-10) enables detection and response: analytics rules activation and tuning, automation rules configuration, playbook development, and workbook deployment. Phase 4 (Weeks 11-16) optimizes operations: custom hunting queries, MITRE ATT&CK gap closure, SOC process integration, runbook documentation, and team training. EPC Group accelerates deployment by 30-40% through pre-built deployment templates, proven rule tuning baselines, and industry-specific playbook libraries for healthcare, finance, and government.

Sentinel workbooks are interactive dashboards built on Azure Workbooks that provide visual analytics and reporting for security operations. They combine KQL queries, charts, graphs, grids, and text into rich operational views. Common workbooks include: Security Operations Efficiency (incident volume, MTTR, closure rates), Identity and Access (sign-in anomalies, risky users, MFA gaps), Network Monitoring (firewall traffic, blocked connections, geo-mapping), Threat Intelligence (IOC matches, TI feed coverage), and Compliance Status (regulatory control mapping, audit trail summaries). Sentinel includes 50+ built-in workbook templates. Custom workbooks can be created for any data source. EPC Group builds industry-specific workbooks — HIPAA security dashboards for healthcare, SOX audit views for financial services, and CMMC compliance trackers for defense contractors.