Audit logs

Audit logs

Audit logs let you track access to your OpenSearch cluster and are useful for compliance purposes or in the aftermath of a security breach. You can configure the categories to be logged, the detail level of the logged messages, and where to store the logs.

To enable audit logging:

Add the following line to opensearch.yml on each node:
```
plugins.security.audit.type: internal_opensearch
```
This setting stores audit logs on the current cluster. For other storage options, see Audit Log Storage Types.
Restart each node.

After this initial setup, you can use OpenSearch Dashboards to manage your audit log categories and other settings. In OpenSearch Dashboards, choose Security, Audit logs.

Tracked events

Audit logging records events in two ways: HTTP requests (REST) and the transport layer.

Event	Logged on REST	Logged on transport	Description
`FAILED_LOGIN`	Yes	Yes	The credentials of a request could not be validated, most likely because the user does not exist or the password is incorrect.
`AUTHENTICATED`	Yes	Yes	A user successfully authenticated.
`MISSING_PRIVILEGES`	No	Yes	The user does not have the required permissions to execute the request.
`GRANTED_PRIVILEGES`	No	Yes	A user made a successful request to OpenSearch.
`SSL_EXCEPTION`	Yes	Yes	An attempt was made to access OpenSearch without a valid SSL/TLS certificate.
`opensearch_SECURITY_INDEX_ATTEMPT`	No	Yes	An attempt was made to modify the Security plugin internal user and privileges index without the required permissions or TLS admin certificate.
`BAD_HEADERS`	Yes	Yes	An attempt was made to spoof a request to OpenSearch with the Security plugin internal headers.

These default log settings work well for most use cases, but you can change settings to save storage space or adapt the information to your exact needs.

Exclude categories

To exclude categories, set:

plugins.security.audit.config.disabled_rest_categories: <disabled categories>
plugins.security.audit.config.disabled_transport_categories: <disabled categories>

For example:

plugins.security.audit.config.disabled_rest_categories: AUTHENTICATED, opensearch_SECURITY_INDEX_ATTEMPT
plugins.security.audit.config.disabled_transport_categories: GRANTED_PRIVILEGES

If you want to log events in all categories, use NONE:

plugins.security.audit.config.disabled_rest_categories: NONE
plugins.security.audit.config.disabled_transport_categories: NONE

Disable REST or the transport layer

By default, the Security plugin logs events on both REST and the transport layer. You can disable either type:

plugins.security.audit.enable_rest: false
plugins.security.audit.enable_transport: false

Disable request body logging

By default, the Security plugin includes the body of the request (if available) for both REST and the transport layer. If you do not want or need the request body, you can disable it:

plugins.security.audit.log_request_body: false

Log index names

By default, the Security plugin logs all indices affected by a request. Because index names can be aliases and contain wildcards/date patterns, the Security plugin logs the index name that the user submitted and the actual index name to which it resolves.

For example, if you use an alias or a wildcard, the audit event might look like:

audit_trace_indices: [
  "human*"
],
audit_trace_resolved_indices: [
  "humanresources"
]

You can disable this feature by setting:

plugins.security.audit.resolve_indices: false

Disabling this feature only takes effect if plugins.security.audit.log_request_body is also set to false.

Configure bulk request handling

Bulk requests can contain many indexing operations. By default, the Security plugin only logs the single bulk request, not each individual operation.

The Security plugin can be configured to log each indexing operation as a separate event:

plugins.security.audit.resolve_bulk_requests: true

This change can create a massive number of events in the audit logs, so we don’t recommend enabling this setting if you make heavy use of the _bulk API.

Exclude requests

You can exclude certain requests from being logged completely, by either configuring actions (for transport requests) and/or HTTP request paths (REST):

plugins.security.audit.ignore_requests: ["indices:data/read/*", "SearchRequest"]

Exclude users

By default, the Security plugin logs events from all users, but excludes the internal OpenSearch Dashboards server user kibanaserver. You can exclude other users:

plugins.security.audit.ignore_users:
  - kibanaserver
  - admin

If requests from all users should be logged, use NONE:

plugins.security.audit.ignore_users: NONE

Configure the audit log index name

By default, the Security plugin stores audit events in a daily rolling index named auditlog-YYYY.MM.dd. You can configure the name of the index in opensearch.yml:

plugins.security.audit.config.index: myauditlogindex

Use a date pattern in the index name to configure daily, weekly, or monthly rolling indices:

plugins.security.audit.config.index: "'auditlog-'YYYY.MM.dd"

For a reference on the date pattern format, see the Joda DateTimeFormat documentation.

(Advanced) Tune the thread pool

The Search plugin logs events asynchronously, which keeps performance impact on your cluster minimal. The plugin uses a fixed thread pool to log events. You can define the number of threads in the pool in opensearch.yml:

plugins.security.audit.threadpool.size: <integer>

The default setting is 10. Setting this value to 0 disables the thread pool, which means the plugin logs events synchronously. To set the maximum queue length per thread:

plugins.security.audit.threadpool.max_queue_len: 100000