User Shell Folders Registry Modification via CommandLine

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.

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Detection logic

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_*

Raw YAML

title: User Shell Folders Registry Modification via CommandLine
id: 8f3ab69a-aa22-4943-aa58-e0a52fdf6818
related:
    - id: 9c226817-8dc9-46c2-a58d-66655aafd7dc
      type: similar
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
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 ' # reg.exe modification
            - 'New-ItemProperty'
            - 'Set-ItemProperty'
            - 'si ' # short for Set-ItemProperty
    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' # covers both 'Startup' and 'Common Startup'
    condition: all of selection_*
falsepositives:
    - Usage of reg.exe or PowerShell to modify User Shell Folders for legitimate purposes; but rare.
level: high
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_user_shell_folders_registry_modification/info.yml
simulation:
    - type: atomic-red-team
      name: Change Startup Folder - HKLM Modify User Shell Folders Common Startup Value
      technique: T1547.001
      atomic_guid: acfef903-7662-447e-a391-9c91c2f00f7b