Visibility and Logging Strategy

Effective security monitoring requires comprehensive visibility into your environment. You cannot detect attacks against systems you can't see. Developing a logging strategy that balances completeness, performance, and cost is essential for security operations.

The Visibility Imperative

Attackers thrive in blind spots. If you don't collect logs from a system, you won't detect attacks against it. If logs lack sufficient detail, investigations stall. If retention is too short, you can't investigate incidents discovered after the fact.

Start by mapping your environment. What systems exist? What data do they hold? What would attackers target? Which systems would attackers traverse to reach their objectives? This threat-informed approach prioritizes visibility where it matters most.

Prioritizing Log Sources

Not all logs provide equal security value. Authentication logs are universally critical—successful and failed logins, privilege changes, and account modifications reveal credential-based attacks. Every domain controller, authentication server, and identity provider should send logs to your SIEM.

Endpoint logs capture what happens on individual systems. Windows Security logs record local events. Sysmon dramatically improves Windows visibility, logging process creation with command lines, network connections, and file creation. EDR platforms provide even richer telemetry.

Network security devices guard boundaries. Firewall logs show what enters and exits. Web proxy logs reveal HTTP activity. DNS logs expose domain lookups—critical for detecting communication with malicious infrastructure.

Cloud services require dedicated attention. AWS CloudTrail, Azure Activity Logs, GCP Audit Logs, and Microsoft 365 audit logs provide visibility into cloud environments that traditional network monitoring can't reach.

Log Content Decisions

Beyond which sources to log, decide what level of detail to collect. Verbose logging captures everything but creates storage costs and performance impacts. Minimal logging misses important context.

For security-critical sources, err toward verbosity. Endpoint process creation is more useful with command-line arguments than without. Network connections are more investigable with payload data than without. The storage cost usually justifies the investigative value.

For lower-priority sources, adjust accordingly. Application debug logs might not warrant SIEM storage. Internal network flows between trusted systems might not need full capture.

Retention and Performance

Retention policies balance multiple concerns. Compliance requirements may mandate specific retention periods. Investigation needs determine how far back you must search. Storage costs create practical limits.

Many organizations maintain hot storage (readily searchable) for 30-90 days and cold storage (archived, slower to access) for longer periods. The goal is immediate access to recent data while preserving historical data for investigations that look back further.

Consider log collection performance. High-volume sources can overwhelm collection infrastructure. Distributed collection architectures, sufficient indexing capacity, and appropriate hardware sizing all require attention. Nothing is worse than losing log data during an incident because your infrastructure couldn't keep up.