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Elastic Docs ›Elastic Security Solution [7.14] ›Detections and alerts ›Prebuilt rule reference

Rare User Logon

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Rare User Logon

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A machine learning job found an unusual user name in the authentication logs. An unusual user name is one way of detecting credentialed access by means of a new or dormant user account. A user account that is normally inactive, because the user has left the organization, which becomes active, may be due to credentialed access using a compromised account password. Threat actors will sometimes also create new users as a means of persisting in a compromised web application.

Rule type: machine_learning

Machine learning job: auth_rare_user

Machine learning anomaly threshold: 75

Severity: low

Risk score: 21

Runs every: 15 minutes

Searches indices from: now-30m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Authentication
  • Threat Detection
  • ML

Version: 1

Added (Elastic Stack release): 7.14.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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User accounts that are rarely active, such as an SRE or developer logging into a prod server for troubleshooting, may trigger this alert. Under some conditions, a newly created user account may briefly trigger this alert while the model is learning.

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