Security Information and Event Management
A technology platform that aggregates, correlates, and analyzes security log data from across an organization's infrastructure to detect threats, support incident investigation, and meet compliance requirements for centralized security monitoring.
Security Information and Event Management (SIEM) combines two historically separate capabilities: Security Information Management (SIM), which handles log collection and long-term storage, and Security Event Management (SEM), which provides real-time monitoring and correlation. Modern SIEM platforms ingest logs and events from firewalls, servers, endpoints, applications, cloud services, identity providers, and other security tools, then apply correlation rules, statistical models, and increasingly machine learning algorithms to identify security incidents that would be invisible when viewing any single data source in isolation.
SIEM is a central component of compliance programs across frameworks. ISO 27001 Annex A controls on logging (A.8.15) and monitoring (A.8.16) effectively require the capabilities that a SIEM provides — centralized log collection, protection of log integrity, and monitoring for security events. SOC 2 auditors look for evidence of centralized monitoring and the ability to detect and respond to security anomalies, which SIEM directly addresses. NIS2 requires entities to implement measures for incident handling and monitoring, and SIEM serves as the primary platform for these activities. In technology due diligence, the maturity of security monitoring — including SIEM deployment, rule coverage, and alert response processes — is a significant factor in assessing an organization's security posture.
Deploying a SIEM effectively involves more than purchasing a platform. Organizations must determine which log sources to integrate (prioritizing high-value sources like identity systems, firewalls, and critical applications), develop detection rules aligned with their threat model, establish alert triage and escalation procedures, and commit to ongoing tuning to reduce false positives. Retention policies must balance compliance requirements (often 12 months or more) with storage costs. Cloud-native SIEM solutions have reduced the infrastructure burden, and managed SIEM or Security Operations Center (SOC) services can provide 24/7 monitoring for organizations that lack the in-house expertise to operate a SIEM independently.
Related frameworks
Related terms
Audit Trail
A chronological record of system activities that provides documentary evidence of the sequence of events — including who accessed what, when, and what actions were taken. Audit trails are essential for security monitoring, incident investigation, and compliance evidence.
Continuous Monitoring
An ongoing, automated process of observing and evaluating the security posture, compliance status, and operational health of an organization's systems and controls in real time or near-real time, enabling rapid detection of deviations, vulnerabilities, and threats.
Incident Response
The organized approach to detecting, containing, investigating, and recovering from security incidents. An incident response plan defines roles, procedures, and communication protocols to minimize the impact of security breaches and other adverse events.
Intrusion Detection System
A security technology that monitors network traffic or system activities for malicious behavior, policy violations, or suspicious patterns, and generates alerts when potential threats are detected.
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