This is one of four ECS Categorization Fields, and indicates the highest level in the ECS category hierarchy.
event.kind gives high-level information about what type of information the event contains, without being specific to the contents of the event. For example, values of this field distinguish alert events from metric events.
The value of this field can be used to inform how these kinds of events should be handled. They may warrant different retention, different access control, it may also help understand whether the data coming in at a regular interval or not.
This value indicates an event that describes an alert or notable event, triggered by a detection rule.
event.kind:alert is often populated for events coming from firewalls, intrusion detection systems, endpoint detection and response systems, and so on.
This value is the most general and most common value for this field. It is used to represent events that indicate that something happened.
This value is used to indicate that this event describes a numeric measurement taken at given point in time.
Examples include CPU utilization, memory usage, or device temperature.
Metric events are often collected on a predictable frequency, such as once every few seconds, or once a minute, but can also be used to describe ad-hoc numeric metric queries.
The state value is similar to metric, indicating that this event describes a measurement taken at given point in time, except that the measurement does not result in a numeric value, but rather one of a fixed set of categorical values that represent conditions or states.
Examples include periodic events reporting Elasticsearch cluster state (green/yellow/red), the state of a TCP connection (open, closed, fin_wait, etc.), the state of a host with respect to a software vulnerability (vulnerable, not vulnerable), and the state of a system regarding compliance with a regulatory standard (compliant, not compliant).
Note that an event that describes a change of state would not use
event.kind:state, but instead would use event.kind:event since a state change fits the more general event definition of something that happened.
State events are often collected on a predictable frequency, such as once every few seconds, once a minute, once an hour, or once a day, but can also be used to describe ad-hoc state queries.
This value indicates that an error occurred during the ingestion of this event, and that event data may be missing, inconsistent, or incorrect.
event.kind:pipeline_error is often associated with parsing errors.
This value is used by the Elastic SIEM app to denote an Elasticsearch document that was created by a SIEM detection engine rule.
A signal will typically trigger a notification that something meaningful happened and should be investigated.
Usage of this value is reserved, and pipelines should not populate
event.kind with the value "signal".