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-*

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: 1

Added (Elastic Stack release): 7.10.0

Rule authors: Elastic

Rule license: Elastic License

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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The GCP Filebeat module must be enabled to use this rule.

Rule query

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

Threat mapping

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Framework: MITRE ATT&CKTM