SIEM — Security Information and Event Management

A SIEM (Security Information and Event Management) system aggregates log and event data from servers, applications, network devices and business systems into a central platform, then correlates that data to detect and alert on potential security incidents. For SME operators of ERP and connected systems, a SIEM provides a unified view of who accessed what, when, and from where. It combines the historical reporting of log management with near real-time event correlation, supporting threat detection, incident response and compliance evidence. SIEM is a building block of a broader security operations capability rather than a single product feature, and is frequently discussed alongside obligations under frameworks such as NIS-2.

What a SIEM does

A SIEM platform performs several distinct functions. It ingests log data from many sources (operating systems, databases, applications, firewalls, identity providers), normalises that data into a common format, and stores it for retention and later analysis. On top of this collected data it runs correlation rules and increasingly statistical or machine-learning models to surface activity that may indicate a threat, such as repeated failed logins, privilege escalation, or data exports outside normal patterns. When a rule fires, the SIEM raises an alert and can feed an incident-response workflow.

• Log collection and normalisation from heterogeneous sources
• Correlation of events across systems to identify attack patterns
• Alerting, dashboards and investigation tooling for analysts
• Long-term retention to support audits and forensic review

Relevance for ERP environments

An ERP system holds financial records, master data and personal data, which makes it an attractive target and a sensitive asset. Feeding ERP application logs, database access logs and authentication events into a SIEM lets an organisation detect anomalous access to that data and reconstruct what happened after an incident. This complements, rather than replaces, the application-level audit trail inside the ERP: the audit trail records business changes within the system, while the SIEM correlates those records with infrastructure and identity events from outside it. Integration with the organisation's identity layer, for example Active Directory or a single sign-on provider, allows the SIEM to tie events to specific users.

SIEM and compliance

Security and data-protection regimes expect organisations to monitor for, detect and respond to incidents, and to retain evidence of having done so. A SIEM supports these expectations by centralising log evidence and demonstrating that monitoring is in place. In the EU and German context this is relevant to NIS-2 obligations for in-scope entities, to data-protection accountability under GDPR, and to assurance reports such as SOC 2 where a service provider must show effective logging and monitoring controls. A SIEM does not by itself make an organisation compliant; it is one control among many.

Practical considerations for SMEs

SIEM platforms range from on-premises software to cloud-delivered services, and many smaller organisations consume SIEM as a managed service or as part of a managed detection and response (MDR) offering rather than running it in-house. Key practical factors include the volume of data ingested (which often drives licensing cost), the quality and tuning of correlation rules to avoid alert fatigue, retention periods needed for audit and legal purposes, and the analyst capacity required to investigate alerts. A poorly tuned SIEM generates noise; a well-tuned one materially shortens the time to detect and contain an incident. Because the value depends heavily on which sources are connected and how rules are maintained, a SIEM is best understood as an ongoing operational programme, not a one-off installation.

Related Topics

• Audit trail
• Single sign-on
• ERP