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[New Rule] Microsoft Entra ID Excessive Account Lockouts Detected #4782

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Merged
merged 6 commits into from
Jun 10, 2025

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terrancedejesus
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Summary - What I changed

Adds a new rule for Entra ID excessive account lockouts being reported as error codes when attempting authentication. This may be indicative of brute forcing attempts by an adversary. Please see linked issue for more details.

How To Test

  • Query can be tested in TRADE stack.

Checklist

  • Added a label for the type of pr: bug, enhancement, schema, maintenance, Rule: New, Rule: Deprecation, Rule: Tuning, Hunt: New, or Hunt: Tuning so guidelines can be generated
  • Added the meta:rapid-merge label if planning to merge within 24 hours
  • Secret and sensitive material has been managed correctly
  • Automated testing was updated or added to match the most common scenarios
  • Documentation and comments were added for features that require explanation

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github-actions bot commented Jun 6, 2025

Rule: New - Guidelines

These guidelines serve as a reminder set of considerations when proposing a new rule.

Documentation and Context

  • Detailed description of the rule.
  • List any new fields required in ECS/data sources.
  • Link related issues or PRs.
  • Include references.

Rule Metadata Checks

  • creation_date matches the date of creation PR initially merged.
  • min_stack_version should support the widest stack versions.
  • name and description should be descriptive and not include typos.
  • query should be inclusive, not overly exclusive, considering performance for diverse environments. Non ecs fields should be added to non-ecs-schema.json if not available in an integration.
  • min_stack_comments and min_stack_version should be included if the rule is only compatible starting from a specific stack version.
  • index pattern should be neither too specific nor too vague, ensuring it accurately matches the relevant data stream (e.g., use logs-endpoint.process-* for process data).
  • integration should align with the index. If the integration is newly introduced, ensure the manifest, schemas, and new_rule.yaml template are updated.
  • setup should include the necessary steps to configure the integration.
  • note should include any additional information (e.g. Triage and analysis investigation guides, timeline templates).
  • tags should be relevant to the threat and align/added to the EXPECTED_RULE_TAGS in the definitions.py file.
  • threat, techniques, and subtechniques should map to ATT&CK always if possible.

New BBR Rules

  • building_block_type should be included if the rule is a building block and the rule should be located in the rules_building_block folder.
  • bypass_bbr_timing should be included if adding custom lookback timing to the rule.

Testing and Validation

  • Provide evidence of testing and detecting the expected threat.
  • Check for existence of coverage to prevent duplication.

@terrancedejesus terrancedejesus marked this pull request as ready for review June 6, 2025 17:49
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@imays11 imays11 left a comment

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Is this rule why you excluded 50053 from the larger brute force rule?

Comment on lines 110 to 111
AND user_agent != "Mozilla/5.0 (compatible; MSAL 1.0) PKeyAuth/1.0"
AND asn_org != "MICROSOFT-CORP-MSN-AS-BLOCK"
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are those really necessary, they make t easy (Esp user agent to bypass the rule) ?

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It filters out any MSAL-based auth for proof-of-possesion so mainly certificates for device authentication. Your right, I don't think we have to filter out in this instance for lockouts. However, UAs are unfortunately sometimes the only good fingerprint we may have globally for cloud workloads or IdP based requests.

@terrancedejesus terrancedejesus merged commit 9569aa4 into main Jun 10, 2025
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@terrancedejesus terrancedejesus deleted the new-rule-excessive-account-lockouts-entra-id branch June 10, 2025 15:31
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[New Rule] Microsoft Entra ID Exccessive Account Lockouts Detected
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