SIEM Selection Guide: What to Measure (Not Just Buy)

Overview

The “best SIEM” is the one that your team can operate: ingest the right logs, build and test detections, investigate quickly, and produce audit-ready evidence.

Define requirements

• What threats matter (ransomware, account takeover, insider, cloud misconfig)?
• What must you detect in under 15–30 minutes?
• What compliance reporting do you need (UU PDP, ISO 27001, sector regulations)?
• What is your coverage scope (endpoints, identity, cloud, network, apps)?

Telemetry & retention

• Priority logs: identity auth, endpoint activity, admin changes, cloud audit logs.
• Retention: choose based on investigations and compliance, then model cost realistically.
• Normalization: consistent fields and parsing impact every downstream query.

Detection workflow

Evaluate how the platform supports the cycle: hypothesis → build → validate → tune → deploy → measure.

• Rule management and versioning
• Testing with sample events and replay
• Alert enrichment and investigation views
• Case management and handoffs

Cost drivers (don’t get surprised)

• Ingest pricing (GB/day), retention tiers, and query costs
• Log sources that explode volume (DNS/proxy/netflow) without filtering
• Engineering time to maintain parsing and detections
• Integration and automation add-ons

Evaluation scorecard (simple)