SIEM systems compared: Splunk, Elastic, Wazuh, Microsoft Sentinel

A Security Information and Event Management (SIEM) system aggregates logs and security telemetry, correlates events, and supports detection and investigation. The market has consolidated to four practical options for mid-market and enterprise: Splunk Enterprise Security, Elastic Security, Wazuh (open source), and Microsoft Sentinel. Each has fundamentally different economics and operational profiles.

Splunk Enterprise Security is the historical leader and benchmark for query speed and detection content. SPL (Search Processing Language) is mature, accelerated data models like CIM streamline detection authoring, and the Splunk-curated detection content via Enterprise Security is among the strongest commercial offerings. Cost is the major constraint: licensing is volume-based (data ingested per day) and a 500 GB/day deployment runs into hundreds of thousands of USD per year. Splunk Cloud avoids on-prem operations but does not lower license cost.

Elastic Security uses the same Elasticsearch engine as the broader stack. Detection rules are written in EQL or KQL, and pre-built rules cover MITRE ATT&CK comprehensively. Pricing is by hot-storage RAM rather than ingest volume, often half the cost of Splunk for similar workloads. Operational complexity is the trade-off — running an Elastic cluster at scale requires real expertise. Elastic Cloud reduces this but still costs more than self-hosting once data exceeds a few TB.

Wazuh is open source and free. It provides agent-based file integrity monitoring, vulnerability detection, and rule-based alerting on top of OpenSearch. For small to mid-size Azerbaijani companies — under 200 endpoints — Wazuh covers compliance use cases for ISO 27001 logging clauses at zero license cost. Microsoft Sentinel is the natural choice for organizations standardized on Azure. Pricing is per GB ingested with a Defender XDR connector providing free Microsoft 365 telemetry. KQL is approachable, and Microsoft-curated content is solid. Pick based on your existing stack, your detection-engineering bench depth, and your appetite for operations. The wrong fit doubles cost and leaves alerts unanswered.