How SIEM works
A SIEM ingests logs from firewalls, servers, endpoints, cloud services, identity systems and applications. It normalizes them into a common format, stores them for search and applies correlation rules, analytics and threat intelligence to spot patterns that individual logs would not reveal.
When conditions are met, such as impossible travel followed by a mailbox rule change, it raises an alert for an analyst. Dashboards, case management and automated playbooks support triage, while retained logs serve as evidence for forensics and audits. Dashboards give management ongoing visibility into alerts, trends and compliance status.
Why it matters for Canadian organizations
Without centralized logging, intrusions can go unnoticed for long periods. A SIEM provides the visibility needed to detect attacks early and to reconstruct what happened, which is essential when assessing whether a breach poses a real risk of significant harm under PIPEDA.
Many frameworks require log retention and review, including PCI-DSS and OSFI B-13 expectations. Value depends on tuning, however: poorly configured SIEMs generate noise that analysts ignore. Data volume drives cost, so decide which logs have security value before connecting everything.
How to implement it
Start with use cases rather than data volume. Identify the threats and compliance needs that matter, then onboard the log sources that support them: identity, endpoints, email, firewalls and cloud audit logs. Define retention periods and access controls.
Tune rules continuously, map detections to MITRE ATT&CK and track false-positive rates. Because a SIEM needs constant attention and 24/7 analysts, many organizations pair it with a managed SOC service. Test detections with simulated attacks so you know they work. Plan for analyst coverage outside business hours, because attacks rarely wait.
Frequently asked questions
What does a SIEM do?
It centralizes logs from many systems, correlates events to detect suspicious activity, alerts analysts, and stores data for investigations and compliance reporting. Correlation of many sources is what makes a SIEM different from basic logging.
What is the difference between SIEM and SOAR?
SIEM detects and alerts based on collected data. SOAR automates and orchestrates the response to those alerts through playbooks and integrations. They are often used together. It adds searchable log retention that supports regulatory and legal requirements.
Do small organizations need a SIEM?
Not always their own. Smaller organizations often use a managed SIEM or SOC service, gaining centralized monitoring and expert analysts without the cost and staffing of running the platform themselves. Managed offerings provide expert tuning and monitoring.
Related service: SIEM