Map data fields to entities in Microsoft Sentinel

Note

Azure Sentinel is now called Microsoft Sentinel, and we’ll be updating these pages in the coming weeks. Learn more about recent Microsoft security enhancements.

Important

  • See "Notes on the new version" at the end of this document for important information about backward compatibility and differences between the new and old versions of entity mapping.

Introduction

Entity mapping is an integral part of the configuration of scheduled query analytics rules. It enriches the rules' output (alerts and incidents) with essential information that serves as the building blocks of any investigative processes and remedial actions that follow.

The procedure detailed below is part of the analytics rule creation wizard. It's treated here independently to address the scenario of adding or changing entity mappings in an existing analytics rule.

How to map entities

  1. From the Microsoft Sentinel navigation menu, select Analytics.

  2. Select a scheduled query rule and select Edit from the details pane. Or create a new rule by clicking Create > Scheduled query rule at the top of the screen.

  3. Select the Set rule logic tab.

  4. In the Alert enrichment section, expand Entity mapping.

    Expand entity mapping

  5. In the now-expanded Entity mapping section, select an entity type from the Entity type drop-down list.

    Choose an entity type

  6. Select an identifier for the entity. Identifiers are attributes of an entity that can sufficiently identify it. Choose one from the Identifier drop-down list, and then choose a data field from the Value drop-down list that will correspond to the identifier. With some exceptions, the Value list is populated by the data fields in the table defined as the subject of the rule query.

    You can define up to three identifiers for a given entity. Some identifiers are required, others are optional. You must choose at least one required identifier. If you don't, a warning message will instruct you which identifiers are required. For best results - for maximum unique identification - you should use strong identifiers whenever possible, and using multiple strong identifiers will enable greater correlation between data sources. See the full list of available entities and identifiers.

    Map fields to entities

  7. Click Add new entity to map more entities. You can map up to five entities in a single analytics rule. You can also map more than one of the same type. For example, you can map two IP entities, one from a source IP address field and one from a destination IP address field. This way you can track them both.

    If you change your mind, or if you made a mistake, you can remove an entity mapping by clicking the trash can icon next to the entity drop-down list.

  8. When you have finished mapping entities, click the Review and create tab. Once the rule validation is successful, click Save.

Note

  • Each mapped entity can identify up to ten entities.

    • If an alert contains more than ten items that correspond to a single entity mapping, only the first ten will be recognized as entities and be able to be analyzed as such.
    • This limitation applies to actual mappings, not to entity types. So if you have three different mapped entities for IP addresses (say, source, destination, and gateway), each of those mappings can accommodate ten entities.
  • The size limit for an entire alert is 64 KB.

    • Alerts that grow larger than 64 KB will be truncated. As entities are identified, they are added to the alert one by one until the alert size reaches 64 KB, and any remaining entities are dropped from the alert.

Notes on the new version

  • As the new version is now generally available (GA), the feature-flag workaround to use the old version is no longer available.

  • If you had previously defined entity mappings for this analytics rule using the old version, they will be automatically converted to the new version.

Next steps

In this document, you learned how to map data fields to entities in Microsoft Sentinel analytics rules. To learn more about Microsoft Sentinel, see the following articles: