IT-Sicherheit

SIEM & Security Monitoring: Detect Threats Before It's Too Late

Nico FreitagIT-Sicherheit

You can't protect what you can't see. Without security monitoring, you're flying blind – attackers move undetected in corporate networks for an average of 204 days before discovery. SIEM (Security Information and Event Management) is the central platform that collects security data from all systems, correlates it, and detects threats in real-time.

What Is SIEM and Why Do You Need It?

SIEM combines two functions: Security Information Management (SIM) – Long-term storage and analysis of log data. Security Event Management (SEM) – Real-time monitoring and alerting for suspicious activities. What SIEM concretely does: - Collect logs from firewalls, servers, endpoints, cloud services - Correlate events (one failed login is harmless, 100 in 5 minutes isn't) - Detect anomalies - Generate compliance reports - Trigger automatic alerts For effective security strategy, SIEM together with Zero Trust is indispensable.

SIEM Solutions Compared

The most important SIEM platforms: Enterprise: - Splunk Enterprise Security – Market leader, very powerful, expensive - IBM QRadar – Strong correlation, good Community Edition - Microsoft Sentinel – Cloud-native, good Azure integration SMB-friendly: - Elastic Security – Open source core, scalable - Wazuh – Open source, host-based - Graylog – Log management with security features Managed SIEM (SOCaaS): For SMBs without security teams: from approx. 2,000 euros/month. At Axis/Port., we advise on selecting the right SIEM solution.

What Should You Monitor?

Not everything is equally important. Prioritize: Critical: - Authentication logs (AD, Azure AD, Okta) - Firewall logs - VPN logs - Email security logs High: - Endpoint logs (EDR data) - Cloud audit logs (AWS CloudTrail, Azure Activity) - DNS logs Medium: - Web server logs - Database access logs - Application logs Alerting Use Cases: - Brute force attacks - Lateral movement - Data exfiltration - Privilege escalation

SOAR: Automating the Response

SOAR complements SIEM with automatic responses: Examples: - Auto-lock account after 10 failed logins - Auto-isolate endpoint on malware detection - Auto-create tickets for security team - Auto-enrich alerts with threat intelligence Tools: - Microsoft Sentinel has SOAR integrated - Palo Alto Cortex XSOAR - Splunk SOAR - TheHive + Cortex (open source) SOAR reduces response time from hours to seconds.

Implementing SIEM: A Staged Plan

Biggest mistake: Doing everything at once. A pragmatic staged plan: Phase 1 (Month 1-2): Basics - Integrate authentication and firewall logs - Configure basic alerts - Train team Phase 2 (Month 3-4): Expansion - Add endpoint and cloud logs - Fine-tune correlation rules - Reduce false positives Phase 3 (Month 5-6): Advanced - Set up SOAR automation - Integrate threat intelligence feeds - Create custom dashboards An Incident Response Plan must exist in parallel – SIEM detects threats, IRP defines the response.

Fazit

SIEM is a necessity, not a luxury. Start with critical log sources and expand gradually. At Axis/Port., we help with selection, implementation, and operation of the right SIEM solution.

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