Detection rules › Sigma
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.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | T1112 Modify Registry |
| Defense Evasion | T1112 Modify Registry |
| Impact | T1491.001 Defacement: Internal Defacement |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 1 | Process creation |
Stages and Predicates
Stage 1: all of selection_reg_img
or:
Image|endswith: '\reg.exe'
OriginalFileName: reg.exe
Stage 2: all of selection_reg_flag
CommandLine|contains: add
Stage 3: selection_keys
or:
CommandLine|contains: 'Control Panel\Desktop'
CommandLine|contains: 'CurrentVersion\Policies\ActiveDesktop'
CommandLine|contains: 'CurrentVersion\Policies\System'
Stage 4: 1 of selection_cli_reg_1
CommandLine|contains: '/d 1'
CommandLine|contains: '/v NoChangingWallpaper'
Stage 5: 1 of selection_cli_reg_2
CommandLine|contains: '/t REG_SZ'
CommandLine|contains: '/v Wallpaper'
Stage 6: 1 of selection_cli_reg_3
CommandLine|contains: '/d 2'
CommandLine|contains: '/v WallpaperStyle'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
CommandLine | match |
|
Image | ends_with |
|
OriginalFileName | eq |
|