Detectionmediumtest
Potentially Suspicious Desktop Background Change Using Reg.EXE
Detects the execution of "reg.exe" to alter registry keys that would replace the user's desktop background. This is a common technique used by malware to change the desktop background to a ransom note or other image.
Convert In Phoenix Studio
Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.
Launch
Log Source
WindowsProcess Creation
ProductWindows← raw: windows
CategoryProcess Creation← raw: process_creation
Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.
Detection Logic
Detection Logic6 selectors
detection:
# TODO: Improve this to also focus on variation using PowerShell and other CLI tools
selection_reg_img:
- Image|endswith: '\reg.exe'
- OriginalFileName: 'reg.exe'
selection_reg_flag:
CommandLine|contains: 'add'
selection_keys:
CommandLine|contains:
- 'Control Panel\Desktop'
- 'CurrentVersion\Policies\ActiveDesktop'
- 'CurrentVersion\Policies\System'
selection_cli_reg_1:
CommandLine|contains|all:
- '/v NoChangingWallpaper'
- '/d 1' # Prevent changing desktop background
selection_cli_reg_2:
CommandLine|contains|all:
- '/v Wallpaper'
- '/t REG_SZ'
selection_cli_reg_3:
CommandLine|contains|all:
- '/v WallpaperStyle'
- '/d 2' # Stretch
condition: all of selection_reg_* and selection_keys and 1 of selection_cli_reg_*False Positives
Administrative scripts that change the desktop background to a company logo or other image.
MITRE ATT&CK
Techniques
Sub-techniques
Rule Metadata
Rule ID
8cbc9475-8d05-4e27-9c32-df960716c701
Status
test
Level
medium
Type
Detection
Created
Thu Dec 21
Path
rules/windows/process_creation/proc_creation_win_reg_desktop_background_change.yml
Raw Tags
attack.persistenceattack.defense-evasionattack.impactattack.t1112attack.t1491.001