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Elastic Docs ›Elastic Security Solution [7.14] ›Detections and alerts ›Prebuilt rule reference
« Attempted Bypass of Okta MFA Attempts to Brute Force an Okta User Account »

Attempts to Brute Force a Microsoft 365 User Accountedit

Identifies attempts to brute force a Microsoft 365 user account. An adversary may attempt a brute force attack to obtain unauthorized access to user accounts.

Rule type: threshold

Rule indices:

  • filebeat-*
  • logs-o365*

Severity: high

Risk score: 73

Runs every: 5 minutes

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

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Cloud
  • Microsoft 365
  • Continuous Monitoring
  • SecOps
  • Identity and Access

Version: 5 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 7.14.0

Rule authors: Elastic, Willem D’Haese, Austin Songer

Rule license: Elastic License v2

Potential false positivesedit

Automated processes that attempt to authenticate using expired credentials and unbounded retries may lead to false positives.

Investigation guideedit

Config

The Microsoft 365 Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.

Rule queryedit

event.dataset:o365.audit and event.provider:(AzureActiveDirectory or
Exchange) and event.category:authentication and
event.action:(UserLoginFailed or
PasswordLogonInitialAuthUsingPassword) and not
o365.audit.LogonError:(UserAccountNotFound or
EntitlementGrantsNotFound or UserStrongAuthEnrollmentRequired or
UserStrongAuthClientAuthNRequired or InvalidReplyTo) and
event.outcome:failure

Threat mappingedit

Framework: MITRE ATT&CKTM

Rule version historyedit

Version 5 (7.14.0 release)

  • Updated query, changed from:

    event.dataset:o365.audit and event.provider:AzureActiveDirectory and
event.category:authentication and event.action:UserLoginFailed and
event.outcome:failure
Version 3 (7.13.0 release)
  • Formatting only
Version 2 (7.12.0 release)
  • Formatting only
« Attempted Bypass of Okta MFA Attempts to Brute Force an Okta User Account »