Potentially Suspicious Desktop Background Change Using Reg.EXE

detection:
  selection_cli_reg_1:
    CommandLine|contains|all:
      - '/v NoChangingWallpaper'
      - '/d 1'
  selection_cli_reg_2:
    CommandLine|contains|all:
      - '/v Wallpaper'
      - '/t REG_SZ'
  selection_cli_reg_3:
    CommandLine|contains|all:
      - '/v WallpaperStyle'
      - '/d 2'
  selection_keys:
    CommandLine|contains:
      - 'Control Panel\Desktop'
      - 'CurrentVersion\Policies\ActiveDesktop'
      - 'CurrentVersion\Policies\System'
  selection_reg_flag:
    CommandLine|contains: 'add'
  selection_reg_img:
    - Image|endswith: '\reg.exe'
    - OriginalFileName: 'reg.exe'
  condition: all of selection_reg_* and selection_keys and 1 of selection_cli_reg_*

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Stephen Lincoln @slincoln-aiq (AttackIQ), under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

None of the everyday examples and documented commands on CmdID’s program pages trips it. To see whether a command line does, paste it into CmdID.