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Anomaly detection security

You can use the Security plugin with anomaly detection in OpenSearch to limit non-admin users to specific actions. For example, you might want some users to only be able to create, update, or delete detectors, while others to only view detectors.

All anomaly detection indexes are protected as system indexes. Only a super admin user or an admin user with a TLS certificate can access system indexes. For more information, see System indexes.

Security for anomaly detection works the same as security for alerting.

Basic permissions

As an admin user, you can use the Security plugin to assign specific permissions to users based on which APIs they need access to. For a list of supported APIs, see Anomaly detection API.

The Security plugin has two built-in roles that cover most anomaly detection use cases: anomaly_full_access and anomaly_read_access. For descriptions of each, see Predefined roles.

If you use OpenSearch Dashboards to create your anomaly detectors, you may experience access issues even with anomaly_full_access. This issue has been resolved in OpenSearch 2.17, but for earlier versions, the following additional permissions need to be added:

• indices:data/read/search – You need this permission because the Anomaly Detection plugin needs to search the data source in order to validate whether there is enough data to train the model.
• indices:admin/mappings/fields/get and indices:admin/mappings/fields/get* – You need these permissions to validate whether the given data source has a valid timestamp field and categorical field (in the case of creating a high-cardinality detector).

If these roles don’t meet your needs, mix and match individual anomaly detection permissions to suit your use case. Each action corresponds to an operation in the REST API. For example, the cluster:admin/opensearch/ad/detector/delete permission lets you delete detectors.

A note on alerts and fine-grained access control

When a trigger generates an alert, the detector and monitor configurations, the alert itself, and any notification that is sent to a channel may include metadata describing the index being queried. By design, the plugin must extract the data and store it as metadata outside of the index. Document-level security (DLS) and field-level security (FLS) access controls are designed to protect the data in the index. But once the data is stored outside the index as metadata, users with access to the detector and monitor configurations, alerts, and their notifications will be able to view this metadata and possibly infer the contents and quality of data in the index, which would otherwise be concealed by DLS and FLS access control.

To reduce the chances of unintended users viewing metadata that could describe an index, we recommend that administrators enable role-based access control and keep these kinds of design elements in mind when assigning permissions to the intended group of users. See Limit access by backend role for details.

Selecting remote indexes with fine-grained access control

To use a remote index as a data source for a detector, see the setup steps in Authentication flow in Cross-cluster search. You must use a role that exists in both the remote and local clusters. The remote cluster must map the chosen role to the same username as in the local cluster.

Example: Create a new user on the local cluster

1. Create a new user on the local cluster to use for detector creation:

curl -XPUT -k -u 'admin:<custom-admin-password>' 'https://localhost:9200/_plugins/_security/api/internalusers/anomalyuser' -H 'Content-Type: application/json' -d '{"password":"password"}'

1. Map the new user to the anomaly_full_access role:

curl -XPUT -k -u 'admin:<custom-admin-password>' -H 'Content-Type: application/json' 'https://localhost:9200/_plugins/_security/api/rolesmapping/anomaly_full_access' -d '{"users" : ["anomalyuser"]}'

1. On the remote cluster, create the same user and map anomaly_full_access to that role:

curl -XPUT -k -u 'admin:<custom-admin-password>' 'https://localhost:9250/_plugins/_security/api/internalusers/anomalyuser' -H 'Content-Type: application/json' -d '{"password":"password"}'
curl -XPUT -k -u 'admin:<custom-admin-password>' -H 'Content-Type: application/json' 'https://localhost:9250/_plugins/_security/api/rolesmapping/anomaly_full_access' -d '{"users" : ["anomalyuser"]}'

Custom results index

To use a custom results index, you need additional permissions not included in the default roles provided by the OpenSearch Security plugin. To add these permissions, see Step 1: Define a detector in the Anomaly detection documentation.

(Advanced) Limit access by backend role

Use backend roles to configure fine-grained access to individual detectors based on roles. For example, users of different departments in an organization can view detectors owned by their own department.

First, make sure your users have the appropriate backend roles. Backend roles usually come from an LDAP server or SAML provider, but if you use the internal user database, you can use the REST API to add them manually.

Next, enable the following setting:

PUT _cluster/settings
{
  "transient": {
    "plugins.anomaly_detection.filter_by_backend_roles": "true"
  }
}

Now when users view anomaly detection resources in OpenSearch Dashboards (or make REST API calls), they only see detectors created by users who share at least one backend role. For example, consider two users: alice and bob.

alice has an analyst backend role:

PUT _plugins/_security/api/internalusers/alice
{
  "password": "alice",
  "backend_roles": [
    "analyst"
  ],
  "attributes": {}
}

bob has a human-resources backend role:

PUT _plugins/_security/api/internalusers/bob
{
  "password": "bob",
  "backend_roles": [
    "human-resources"
  ],
  "attributes": {}
}

Both alice and bob have full access to anomaly detection:

PUT _plugins/_security/api/rolesmapping/anomaly_full_access
{
  "backend_roles": [],
  "hosts": [],
  "users": [
    "alice",
    "bob"
  ]
}

Because they have different backend roles, alice and bob cannot view each other’s detectors or their results.

If users do not have backend roles, they still can view other users’ anomaly detection results as long as they have anomaly_read_access. This is the same for users who have anomaly_full_access, as it includes all of the permissions as anomaly_read_access. Administrators should inform users that having anomaly_read_access allows for viewing of the results from any detector in the cluster, including data not directly accessible to them. To limit access to the detector results, administrators should use backend role filters at the time the detector is created. This ensures only users with matching backend roles can access results from those particular detectors.