GCP Storage Bucket Permissions Modification

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Identifies when the Identity and Access Management (IAM) permissions are modified for a Google Cloud Platform (GCP) storage bucket. An adversary may modify the permissions on a storage bucket to weaken their target’s security controls or an administrator may inadvertently modify the permissions, which could lead to data exposure or loss.

Rule type: query

Rule indices:

  • filebeat-*
  • logs-gcp*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-6m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Cloud
  • GCP
  • Continuous Monitoring
  • SecOps
  • Identity and Access

Version: 7 (version history)

Added (Elastic Stack release): 7.10.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Storage bucket permissions may be modified by system administrators. Verify that the configuration change was expected. Exceptions can be added to this rule to filter expected behavior.

Investigation guide

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Rule query

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event.dataset:gcp.audit and event.action:"storage.setIamPermissions"
and event.outcome:success

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 7 (8.4.0 release)
  • Updated query, changed from:

    event.dataset:(googlecloud.audit or gcp.audit) and
    event.action:"storage.setIamPermissions" and event.outcome:success
Version 5 (7.13.0 release)
  • Updated query, changed from:

    event.dataset:(googlecloud.audit or gcp.audit) and
    event.action:storage.setIamPermissions and event.outcome:success
Version 4 (7.12.0 release)
  • Formatting only
Version 3 (7.11.2 release)
  • Formatting only
Version 2 (7.11.0 release)
  • Updated query, changed from:

    event.dataset:googlecloud.audit and
    event.action:storage.setIamPermissions and event.outcome:success