Azure Blob Permissions Modification

Identifies when the Azure role-based access control (Azure RBAC) permissions are modified for an Azure Blob. An adversary may modify the permissions on a blob 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-azure*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: None (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://docs.microsoft.com/en-us/azure/role-based-access-control/built-in-roles

Tags:

Domain: Cloud
Data Source: Azure
Use Case: Identity and Access Audit
Tactic: Defense Evasion
Data Source: Elastic Defend

Version: 103

Rule authors:

Austin Songer

Rule license: Elastic License v2

Investigation guide

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Setup

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

Rule query

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event.dataset:azure.activitylogs and azure.activitylogs.operation_name:(
     "MICROSOFT.STORAGE/STORAGEACCOUNTS/BLOBSERVICES/CONTAINERS/BLOBS/MANAGEOWNERSHIP/ACTION" or
     "MICROSOFT.STORAGE/STORAGEACCOUNTS/BLOBSERVICES/CONTAINERS/BLOBS/MODIFYPERMISSIONS/ACTION") and
  event.outcome:(Success or success)

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: File and Directory Permissions Modification
- ID: T1222
- Reference URL: https://attack.mitre.org/techniques/T1222/

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