TCC Bypass via Mounted APFS Snapshot Access

Identifies the use of the mount_apfs command to mount the entire file system through Apple File System (APFS) snapshots as read-only and with the noowners flag set. This action enables the adversary to access almost any file in the file system, including all user data and files protected by Apple’s privacy framework (TCC).

Rule type: query

Rule indices:

auditbeat-*
logs-endpoint.events.*

Severity: high

Risk score: 73

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://theevilbit.github.io/posts/cve_2020_9771/

Tags:

Elastic
Host
macOS
Threat Detection
Defense Evasion

Version: 1

Added (Elastic Stack release): 7.12.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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event.category : process and event.type : (start or process_started)
and process.name : mount_apfs and process.args :
(/System/Volumes/Data and noowners)

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Direct Volume Access
- ID: T1006
- Reference URL: https://attack.mitre.org/techniques/T1006/

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