Hidden User Creation — Sigma Rule

Rule metadata and linked tags

Author: Daniil Yugoslavskiy, oscd.community. Source status: test; severity: medium. Source dates: 2020-10-10 / 2021-11-27.

{
  "category": "process_creation",
  "product": "macos"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: fdd4a79d1262a7dfe24923949c020151734a6d39f6e0b59e6adc50b9e31128f6

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Hidden User Creation
id: b22a5b36-2431-493a-8be1-0bae56c28ef3
status: test
description: Detects creation of a hidden user account on macOS (UserID < 500) or with IsHidden option
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1564.002/T1564.002.md
author: Daniil Yugoslavskiy, oscd.community
date: 2020-10-10
modified: 2021-11-27
tags:
    - attack.stealth
    - attack.t1564.002
logsource:
    category: process_creation
    product: macos
detection:
    dscl_create:
        Image|endswith: '/dscl'
        CommandLine|contains: 'create'
    id_below_500:
        CommandLine|contains: UniqueID
        CommandLine|re: '([0-9]|[1-9][0-9]|[1-4][0-9]{2})'
    ishidden_option_declaration:
        CommandLine|contains: 'IsHidden'
    ishidden_option_confirmation:
        CommandLine|contains:
            - 'true'
            - 'yes'
            - '1'
    condition: dscl_create and id_below_500 or dscl_create and (ishidden_option_declaration and ishidden_option_confirmation)
falsepositives:
    - Legitimate administration activities
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate administration activities

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1564.002/T1564.002.md