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Entity risk scoring

Learn about the risk scoring engine and its features.

Entity risk scoring is an advanced Elastic Security analytics feature that helps security analysts detect changes in an entity's risk posture, hunt for new threats, and prioritize incident response.

Entity risk scoring allows you to monitor risk score changes of hosts and users in your environment. When generating advanced scoring analytics, the risk scoring engine utilizes threats from its end-to-end XDR use cases, such as SIEM, cloud, and endpoint. It leverages the Elastic SIEM detection engine to generate host and user risk scores from the last 30 days.

It also generates risk scores on a recurring interval, and allows for easy onboarding and management. The engine is built to factor in risks from all Elastic Security use cases, and allows you to customize and control how and when risk is calculated.

Risk scoring inputs

Entity risk scores are determined by the following risk inputs:

Risk inputStorage location
Alerts
.alerts-security.alerts-<space-id> index alias
Asset criticality level
.asset-criticality.asset-criticality-<space-id> index alias

The resulting entity risk scores are stored in the risk-score.risk-score-<space-id> data stream alias.

Note

  • Entities without any alerts, or with only Closed alerts, are not assigned a risk score.
  • To use asset criticality, you must enable the securitySolution:enableAssetCriticality advanced setting.

How is risk score calculated?

  1. The risk scoring engine runs hourly to aggregate Open and Acknowledged alerts from the last 30 days. For each entity, the engine processes up to 10,000 alerts.

  2. The engine groups alerts by host.name or user.name, and aggregates the individual alert risk scores (kibana.alert.risk_score) such that alerts with higher risk scores contribute more than alerts with lower risk scores. The resulting aggregated risk score is assigned to the Alerts category in the entity's risk summary.

  3. The engine then verifies the entity's asset criticality level. If there is no asset criticality assigned, the entity risk score remains equal to the aggregated score from the Alerts category. If a criticality level is assigned, the engine updates the risk score based on the default risk weight for each criticality level. The asset criticality risk input is assigned to the Asset Criticality category in the entity's risk summary.

    Asset criticality levelDefault risk weight
    Low impact
    0.5
    Medium impact
    1
    High impact
    1.5
    Extreme impact
    2

    Note

    Asset criticality levels and default risk weights are subject to change.

  4. Based on the two risk inputs, the risk scoring engine generates a single entity risk score of 0-100. It assigns a risk level by mapping the risk score to one of these levels:

    Risk levelRisk score
    Unknown
    < 20
    Low
    20-40
    Moderate
    40-70
    High
    70-90
    Critical
    > 90

This example shows how the risk scoring engine calculates the user risk score for User_A, whose asset criticality level is Extreme impact.

There are 5 open alerts associated with User_A:

  • Alert 1 with alert risk score 21
  • Alert 2 with alert risk score 45
  • Alert 3 with alert risk score 21
  • Alert 4 with alert risk score 70
  • Alert 5 with alert risk score 21

To calculate the user risk score, the risk scoring engine:

  1. Sorts the associated alerts in descending order of alert risk score:

    • Alert 4 with alert risk score 70
    • Alert 2 with alert risk score 45
    • Alert 1 with alert risk score 21
    • Alert 3 with alert risk score 21
    • Alert 5 with alert risk score 21

  2. Generates an aggregated risk score of 36.16, and assigns it to User_A's Alerts risk category.

  3. Looks up User_A's asset criticality level, and identifies it as Extreme impact.

  4. Generates a new risk input under the Asset Criticality risk category, with a risk contribution score of 16.95.

  5. Increases the user risk score to 53.11, and assigns User_A a Moderate user risk level.

If User_A had no asset criticality level assigned, the user risk score would remain unchanged at 36.16.

Learn how to turn on the risk scoring engine.

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