User Added to Local Administrators Group

 1title: User Added to Local Administrators Group
 2id: ad720b90-25ad-43ff-9b5e-5c841facc8e5
 3related:
 4    - id: ffa28e60-bdb1-46e0-9f82-05f7a61cc06e # Remote Desktop groups
 5      type: similar
 6    - id: 10fb649c-3600-4d37-b1e6-56ea90bb7e09 # Privileged groups
 7      type: similar
 8status: test
 9description: Detects addition of users to the local administrator group via "Net" or "Add-LocalGroupMember".
10references:
11    - https://blog.talosintelligence.com/2022/08/recent-cyber-attack.html?m=1
12author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
13date: 2022/08/12
14modified: 2023/03/02
15tags:
16    - attack.persistence
17    - attack.t1098
18logsource:
19    category: process_creation
20    product: windows
21detection:
22    selection_main:
23        - CommandLine|contains|all:
24              # net.exe
25              - 'localgroup '
26              - ' /add'
27        - CommandLine|contains|all:
28              # powershell.exe
29              - 'Add-LocalGroupMember '
30              - ' -Group '
31    selection_group:
32        CommandLine|contains:
33            - ' administrators '
34            - ' administrateur' # Typo without an 'S' so we catch both
35    condition: all of selection_*
36falsepositives:
37    - Administrative activity
38level: medium