Detection rules › Splunk
Modification Of Wallpaper
The following analytic detects the modification of registry keys related to the desktop wallpaper settings. It leverages Sysmon EventCode 13 to identify changes to the "Control Panel\Desktop\Wallpaper" and "Control Panel\Desktop\WallpaperStyle" registry keys, especially when the modifying process is not explorer.exe or involves suspicious file paths like temp or public directories. This activity is significant as it can indicate ransomware behavior, such as the REVIL ransomware, which changes the wallpaper to display a ransom note. If confirmed malicious, this could signify a compromised machine and the presence of ransomware, leading to potential data encryption and extortion.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Impact | T1491 Defacement |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 13 | RegistryEvent (Value Set) |
Stages and Predicates
Stage 1: search
search ((Details IN ("*\\temp\\*", "*\\users\\public\\*") TargetObject IN ("*\\Control Panel\\Desktop\\Wallpaper", "*\\Control Panel\\Desktop\\WallpaperStyle")) OR (Image!="*\\explorer.exe" TargetObject IN ("*\\Control Panel\\Desktop\\Wallpaper", "*\\Control Panel\\Desktop\\WallpaperStyle"))) EventCode=13
Stage 2: stats
stats BY action, dest, process_guid, process_id, registry_hive, registry_path, registry_key_name, registry_value_data, registry_value_name, status, user_id, vendor_product
Stage 3: search
search
Stage 4: search
search
Stage 5: search
search `macro`
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 |
|---|---|---|
Details | in |
|
EventCode | eq |
|
Image | ne |
|
TargetObject | in |
|