User Shell Folders Registry Modification via CommandLine

Title: User Shell Folders Registry Modification via CommandLine
Status: experimental
Description:Detects modifications to User Shell Folders registry values via reg.exe or PowerShell, which could indicate persistence attempts. Attackers may modify User Shell Folders registry values to point to malicious executables or scripts that will be executed during startup. This technique is often used to maintain persistence on a compromised system by ensuring that malicious payloads are executed automatically.
References:
  -https://www.welivesecurity.com/en/eset-research/muddywater-snakes-riverbank/
Author: Swachchhanda Shrawan Poudel (Nextron Systems)
Date: 2026-01-05
modified:None
Tags:

• -'attack.persistence'
• -'attack.privilege-escalation'
• -'attack.defense-impairment'
• -'attack.t1547.001'
• -'attack.t1112'

Logsource:

• category: process_creation
• product: windows

Detection:
  selection_img:
    - Image|endswith:
      - '\powershell.exe'
      - '\pwsh.exe'
      - '\reg.exe'
    - OriginalFileName:
      - 'powershell.exe'
      - 'pwsh.dll'
      - 'reg.exe'
  selection_cli_action:
    CommandLine|contains:
      -' add '
      -'New-ItemProperty'
      -'Set-ItemProperty'
      -'si '

  selection_cli_paths_root:
    CommandLine|contains:
      -'\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders'
      -'\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders'

  selection_cli_paths_suffix:
    CommandLine|contains: 'Startup'
  condition:all of selection_*
Falsepositives:
  -Usage of reg.exe or PowerShell to modify User Shell Folders for legitimate purposes; but rare.
Level: high