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[New Rule] Adding Coverage for AWS IAM Virtual MFA Device Registration #4626

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terrancedejesus
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@terrancedejesus terrancedejesus commented Apr 16, 2025

Pull Request

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Summary - What I changed

Adds detection coverage for AWS MFA device registration attempts with temporary credentials (user session tokens).

Identifies attempts to register or enable an IAM Virtual MFA device using temporary credentials (access keys starting with 'ASIA'). This may indicate an adversary attempting to escalate privileges or establish persistence using stolen session tokens.

Additional Information:

  • From CloudTrail logs, identifies CreateVirtualMFADevice or EnableMFADevice API operations
  • These operations must also include an access key ID that starts with ASIA, indicating temporary user session tokens being passed in the request
  • It is not odd to create virtual MFA devices in the console or even with long term credentials in AWS configuration file, but with temporary creds is an anomaly.

How To Test

  • Please refer to the meta regarding emulation behavior testing
  • Query can be used in serverless cloud 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

Contributor checklist

@terrancedejesus terrancedejesus added Integration: AWS AWS related rules Domain: Cloud Rule: New Proposal for new rule labels Apr 16, 2025
@terrancedejesus terrancedejesus self-assigned this Apr 16, 2025
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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 April 16, 2025 18:18
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@DefSecSentinel DefSecSentinel left a comment

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LGTM

@terrancedejesus terrancedejesus merged commit 9423779 into main Apr 21, 2025
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@terrancedejesus terrancedejesus deleted the new-rule-aws-persistence-attempt-to-register-virtual-mfa branch April 21, 2025 15:02
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3 participants