Wallpaper blanked via reg.exe and refreshed via rundll32 (Stealer/1.0)
This rule detects unauthorized modification of the desktop wallpaper registry key to an empty string, typically used for desktop defacement or disruptive activity, followed by a system parameter refresh to apply the changes immediately. It monitors for the use of reg.exe to clear the wallpaper registry value and rundll32.exe to invoke the User32.dll UpdatePerUserSystemParameters function, which forces the Windows shell to refresh desktop settings.
Sigma
