Hidden User Creation

 1title: Hidden User Creation
 2id: b22a5b36-2431-493a-8be1-0bae56c28ef3
 3status: test
 4description: Detects creation of a hidden user account on macOS (UserID < 500) or with IsHidden option
 5references:
 6    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1564.002/T1564.002.md
 7author: Daniil Yugoslavskiy, oscd.community
 8date: 2020/10/10
 9modified: 2021/11/27
10tags:
11    - attack.defense_evasion
12    - attack.t1564.002
13logsource:
14    category: process_creation
15    product: macos
16detection:
17    dscl_create:
18        Image|endswith: '/dscl'
19        CommandLine|contains: 'create'
20    id_below_500:
21        CommandLine|contains: UniqueID
22        CommandLine|re: '([0-9]|[1-9][0-9]|[1-4][0-9]{2})'
23    ishidden_option_declaration:
24        CommandLine|contains: 'IsHidden'
25    ishidden_option_confirmation:
26        CommandLine|contains:
27            - 'true'
28            - 'yes'
29            - '1'
30    condition: dscl_create and id_below_500 or dscl_create and (ishidden_option_declaration and ishidden_option_confirmation)
31falsepositives:
32    - Legitimate administration activities
33level: medium