Event Fields

event.action

The action captured by the event.

This describes the information in the event. It is more specific than event.category. Examples are group-add, process-started, file-created. The value is normally defined by the implementer.

type: keyword

example: user-password-change

core

event.agent_id_status

Agents are normally responsible for populating the agent.id field value. If the system receiving events is capable of validating the value based on authentication information for the client then this field can be used to reflect the outcome of that validation.

For example if the agent’s connection is authenticated with mTLS and the client cert contains the ID of the agent to which the cert was issued then the agent.id value in events can be checked against the certificate. If the values match then event.agent_id_status: verified is added to the event, otherwise one of the other allowed values should be used.

If no validation is performed then the field should be omitted.

The allowed values are:

verified - The agent.id field value matches expected value obtained from auth metadata.

mismatch - The agent.id field value does not match the expected value obtained from auth metadata.

missing - There was no agent.id field in the event to validate.

auth_metadata_missing - There was no auth metadata or it was missing information about the agent ID.

type: keyword

example: verified

extended

event.category

This is one of four ECS Categorization Fields, and indicates the second level in the ECS category hierarchy.

event.category represents the "big buckets" of ECS categories. For example, filtering on event.category:process yields all events relating to process activity. This field is closely related to event.type, which is used as a subcategory.

This field is an array. This will allow proper categorization of some events that fall in multiple categories.

type: keyword

Note: this field should contain an array of values.

Important: The field value must be one of the following:

authentication, configuration, database, driver, email, file, host, iam, intrusion_detection, malware, network, package, process, registry, session, threat, vulnerability, web

To learn more about when to use which value, visit the page allowed values for event.category

core

event.code

Identification code for this event, if one exists.

Some event sources use event codes to identify messages unambiguously, regardless of message language or wording adjustments over time. An example of this is the Windows Event ID.

type: keyword

example: 4648

extended

event.created

event.created contains the date/time when the event was first read by an agent, or by your pipeline.

This field is distinct from @timestamp in that @timestamp typically contain the time extracted from the original event.

In most situations, these two timestamps will be slightly different. The difference can be used to calculate the delay between your source generating an event, and the time when your agent first processed it. This can be used to monitor your agent’s or pipeline’s ability to keep up with your event source.

In case the two timestamps are identical, @timestamp should be used.

type: date

example: 2016-05-23T08:05:34.857Z

core

event.dataset

Name of the dataset.

If an event source publishes more than one type of log or events (e.g. access log, error log), the dataset is used to specify which one the event comes from.

It’s recommended but not required to start the dataset name with the module name, followed by a dot, then the dataset name.

type: keyword

example: apache.access

core

event.duration

Duration of the event in nanoseconds.

If event.start and event.end are known this value should be the difference between the end and start time.

type: long

core

event.end

event.end contains the date when the event ended or when the activity was last observed.

type: date

extended

event.hash

Hash (perhaps logstash fingerprint) of raw field to be able to demonstrate log integrity.

type: keyword

example: 123456789012345678901234567890ABCD

extended

event.id

Unique ID to describe the event.

type: keyword

example: 8a4f500d

core

event.ingested

Timestamp when an event arrived in the central data store.

This is different from @timestamp, which is when the event originally occurred. It’s also different from event.created, which is meant to capture the first time an agent saw the event.

In normal conditions, assuming no tampering, the timestamps should chronologically look like this: @timestamp < event.created < event.ingested.

type: date

example: 2016-05-23T08:05:35.101Z

core

event.kind

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.

type: keyword

Important: The field value must be one of the following:

alert, enrichment, event, metric, state, pipeline_error, signal

To learn more about when to use which value, visit the page allowed values for event.kind

core

event.module

Name of the module this data is coming from.

If your monitoring agent supports the concept of modules or plugins to process events of a given source (e.g. Apache logs), event.module should contain the name of this module.

type: keyword

example: apache

core

event.original

Raw text message of entire event. Used to demonstrate log integrity or where the full log message (before splitting it up in multiple parts) may be required, e.g. for reindex.

This field is not indexed and doc_values are disabled. It cannot be searched, but it can be retrieved from _source. If users wish to override this and index this field, please see Field data types in the Elasticsearch Reference.

type: keyword

example: Sep 19 08:26:10 host CEF:0|Security| threatmanager|1.0|100| worm successfully stopped|10|src=10.0.0.1 dst=2.1.2.2spt=1232

core

event.outcome

This is one of four ECS Categorization Fields, and indicates the lowest level in the ECS category hierarchy.

event.outcome simply denotes whether the event represents a success or a failure from the perspective of the entity that produced the event.

Note that when a single transaction is described in multiple events, each event may populate different values of event.outcome, according to their perspective.

Also note that in the case of a compound event (a single event that contains multiple logical events), this field should be populated with the value that best captures the overall success or failure from the perspective of the event producer.

Further note that not all events will have an associated outcome. For example, this field is generally not populated for metric events, events with event.type:info, or any events for which an outcome does not make logical sense.

type: keyword

Important: The field value must be one of the following:

failure, success, unknown

To learn more about when to use which value, visit the page allowed values for event.outcome

core

event.provider

Source of the event.

Event transports such as Syslog or the Windows Event Log typically mention the source of an event. It can be the name of the software that generated the event (e.g. Sysmon, httpd), or of a subsystem of the operating system (kernel, Microsoft-Windows-Security-Auditing).

type: keyword

example: kernel

extended

event.reason

Reason why this event happened, according to the source.

This describes the why of a particular action or outcome captured in the event. Where event.action captures the action from the event, event.reason describes why that action was taken. For example, a web proxy with an event.action which denied the request may also populate event.reason with the reason why (e.g. blocked site).

type: keyword

example: Terminated an unexpected process

extended

event.reference

Reference URL linking to additional information about this event.

This URL links to a static definition of this event. Alert events, indicated by event.kind:alert, are a common use case for this field.

type: keyword

example: https://system.example.com/event/#0001234

extended

event.risk_score

Risk score or priority of the event (e.g. security solutions). Use your system’s original value here.

type: float

core

event.risk_score_norm

Normalized risk score or priority of the event, on a scale of 0 to 100.

This is mainly useful if you use more than one system that assigns risk scores, and you want to see a normalized value across all systems.

type: float

extended

event.sequence

Sequence number of the event.

The sequence number is a value published by some event sources, to make the exact ordering of events unambiguous, regardless of the timestamp precision.

type: long

extended

event.severity

The numeric severity of the event according to your event source.

What the different severity values mean can be different between sources and use cases. It’s up to the implementer to make sure severities are consistent across events from the same source.

The Syslog severity belongs in log.syslog.severity.code. event.severity is meant to represent the severity according to the event source (e.g. firewall, IDS). If the event source does not publish its own severity, you may optionally copy the log.syslog.severity.code to event.severity.

type: long

example: 7

core

event.start

event.start contains the date when the event started or when the activity was first observed.

type: date

extended

event.timezone

This field should be populated when the event’s timestamp does not include timezone information already (e.g. default Syslog timestamps). It’s optional otherwise.

Acceptable timezone formats are: a canonical ID (e.g. "Europe/Amsterdam"), abbreviated (e.g. "EST") or an HH:mm differential (e.g. "-05:00").

type: keyword

extended

event.type

This is one of four ECS Categorization Fields, and indicates the third level in the ECS category hierarchy.

event.type represents a categorization "sub-bucket" that, when used along with the event.category field values, enables filtering events down to a level appropriate for single visualization.

This field is an array. This will allow proper categorization of some events that fall in multiple event types.

type: keyword

Note: this field should contain an array of values.

Important: The field value must be one of the following:

access, admin, allowed, change, connection, creation, deletion, denied, end, error, group, indicator, info, installation, protocol, start, user

To learn more about when to use which value, visit the page allowed values for event.type

core

event.url

URL linking to an external system to continue investigation of this event.

This URL links to another system where in-depth investigation of the specific occurrence of this event can take place. Alert events, indicated by event.kind:alert, are a common use case for this field.

type: keyword

example: https://mysystem.example.com/alert/5271dedb-f5b0-4218-87f0-4ac4870a38fe

extended