What is the definition of an event as it applies to incident handling?

NIST SP 800-61 establishes 'event' as the broadest category, covering any observable occurrence regardless of whether it is benign or malicious, which is the foundational definition used in formal incident handling programs. This broad scope ensures that all activity is captured for triage before determining whether an incident has taken place. Understanding this distinction is critical because not every event becomes an incident, and incident response resources are scoped only to adverse events that meet a defined threshold.

The introduction of malicious code describes a specific type of security incident, which is a subset of events, not the definition of an event itself.

An IDS alert is a mechanism for detecting a potential event but is not the definition of an event, since many events occur without triggering any alert.

An adverse occurrence in an information system more closely aligns with the NIST SP 800-61 definition of an 'incident', not the broader definition of an 'event'.