Mike! Mike! Mike! What day is it? Its Security with Mike!
One of the most critical components of any security organization is a functional SIEM—one that delivers the visibility, threat detection, and response capabilities your organization needs. Without proper planning, a SIEM can quickly become a costly, ineffective log repository instead of a powerful security tool.
As a Technical Security Specialist at Microsoft, I thrive on helping organizations proactively protect their environments through effective security strategies. With over two decades in cybersecurity, I’ve worked in various roles deploying and optimizing SIEM solutions like Microsoft Sentinel, Splunk, and other cloud-native platforms to strengthen security operations.
Before joining Microsoft, I served as Lead Cybersecurity Manager at Ernst & Young, where I saw firsthand how organizations waste money on inefficient SIEM deployments—failing to define use cases, ingesting unnecessary data, or choosing a platform that doesn’t align with their existing infrastructure.
If you’re considering Microsoft Sentinel, you’re already on the right track—but deploying it strategically is key to maximizing its value. In this post, I’ll break down the essential steps to getting Sentinel up and running efficiently—without unnecessary costs or complexity.
1. Microsoft’s Security Footprint: Why Many Organizations Choose Sentinel
Before diving into Sentinel deployment, it’s important to recognize just how dominant Microsoft security solutions have become across industries. If your organization already relies on Microsoft security tools, adopting Sentinel is often the most cost-effective and seamless SIEM choice.
📊 Key Statistics on Microsoft Security Adoption:
- Endpoint Security Leadership: Microsoft holds the largest share of the modern endpoint security market (25.8%), with a 40.7% year-over-year growth, demonstrating rapid adoption of tools like Microsoft Defender for Endpoint.
- SIEM Growth & Adoption: Microsoft Sentinel is now used by 25,000+ organizations, driving over $1 billion in annual revenue, making it one of the fastest-growing SIEM solutions.
- Cloud App Security Presence: Microsoft Cloud App Security has a 14.96% market share in the cloud access security broker (CASB) market, showing strong adoption in SaaS security.
🚀 Why does this matter?
If your organization already uses Microsoft Defender, Azure AD, Office 365, or other Microsoft security tools, Sentinel provides native integrations with zero additional ingestion costs for many critical data sources.
This brings us to our next key consideration: cost efficiency.
2. Cost Considerations: Why Microsoft Sentinel Saves You Money
Many organizations overlook the hidden costs of using a non-Microsoft SIEM. If your infrastructure already includes Microsoft 365, Defender, Azure AD, and other Microsoft services, using a third-party SIEM can create additional integration costs due to:
❌ Manual Data Transfers: Sending Microsoft logs to an external SIEM often requires custom integrations, API calls, or third-party connectors—all of which increase deployment complexity and costs.
❌ Additional Licensing Fees: Many SIEM platforms charge extra for each new log source, requiring you to pay for Microsoft security data you could get for free in Sentinel.
❌ Storage and Ingestion Costs: If you’re collecting logs in Microsoft and exporting them externally, you’re paying for data ingestion twice—once in Microsoft and again in your third-party SIEM.
Free Data Sources in Microsoft Sentinel
One of Sentinel’s biggest advantages is that many critical security data sources are ingested for free, meaning you don’t pay for their log ingestion. These include:
✅ Azure AD sign-in logs (User authentication activity, failed logins, risky sign-ins)
✅ Microsoft Defender for Endpoint, Identity, and Office 365 (Threat intelligence and endpoint alerts)
✅ Office 365 audit logs (Email and file activity)
✅ Microsoft Defender Threat Intelligence (Threat indicators and IOCs)
✅ Azure Activity Logs (Changes to Azure services and configurations)
💡 Pro Tip: If your security operations depend heavily on Microsoft tools, Sentinel is the most cost-efficient SIEM option because it removes ingestion fees for these high-value logs.
3. Prioritize the Right Data Sources (Don’t Collect Everything!)
Even with free data sources, Sentinel operates on a pay-as-you-go model, meaning it’s crucial to only collect logs that matter. Here’s where to focus first:
🔹 Azure AD logs – Track user sign-ins, failed logins, and potential identity-based threats.
🔹 Microsoft Defender alerts – Monitor endpoint, email, and cloud threats in real time.
🔹 Firewall and VPN logs – Identify suspicious network activity and unauthorized access.
🔹 Cloud security logs (AWS, GCP, SaaS apps) – If you’re multi-cloud, pull in external security logs using connectors.
🔹 Critical application logs – ERP, HR, and financial system security logs.
🚨 Avoid unnecessary data ingestion! Exclude low-value logs that don’t contribute to security insights.
4. Optimize Retention & Costs
Since Sentinel pricing is based on GB of ingested data per day, cost optimization is key. Here’s how to reduce unnecessary spending:
✔ Use free data sources where possible (Azure AD, Defender, Office 365).
✔ Define retention policies early (e.g., 30 days for fast queries, 1+ year for compliance).
✔ Leverage Azure Blob Storage for long-term log storage instead of Log Analytics.
✔ Use basic log ingestion for non-security data to minimize costs.
💡 Pro Tip: Scheduled queries allow you to pull logs only when needed, instead of ingesting everything 24/7.
5. Automate Incident Response with Playbooks
A SIEM is only effective if your team acts on alerts quickly. Sentinel makes this easier with playbooks (automated workflows) that integrate with:
📌 Defender for Endpoint – Auto-isolate infected machines.
📌 Azure AD – Disable compromised accounts after a brute-force attack.
📌 Microsoft Teams & Slack – Send real-time security alerts.
📌 ServiceNow & Jira – Automatically create security incident tickets.
🚀 Bonus: Playbooks eliminate manual alert triage, freeing up your SOC team for high-priority investigations.
6. Deploy in Phases to Avoid Overload
To ensure a smooth Sentinel deployment, don’t try to ingest everything at once. Instead, roll out in stages:
🟢 Phase 1: Enable Sentinel in audit mode to collect logs without triggering alerts—this allows you to fine-tune ingestion.
🟡 Phase 2: Turn on high-priority detections (identity threats, endpoint alerts, network activity).
🔴 Phase 3: Automate responses, integrate with third-party tools, and refine detection rules.
A staged rollout prevents data overload, avoids unnecessary costs, and ensures effective monitoring from the start.
Final Thoughts: SIEM Deployment is About Smart Planning
Deploying a SIEM is more than just turning on log collection—it’s about maximizing value while minimizing unnecessary costs.
✔ If your organization is already using Microsoft tools, Sentinel is the most cost-effective option, thanks to free data ingestion for critical security logs.
✔ Third-party SIEMs often require expensive integrations, making them a costlier choice when transferring Microsoft security data externally.
✔ By prioritizing the right logs, optimizing retention, and using automation, Sentinel delivers enterprise-grade security at a fraction of the cost of traditional SIEMs.
🔹 Thinking of deploying Sentinel? Let’s discuss your challenges and best practices in the comments!
This version now seamlessly integrates statistics while keeping it engaging and informative. Does this align with your vision? 🚀