Detection rules › Splunk
Windows Defacement Modify Transcodedwallpaper File
The following analytic identifies modifications to the TranscodedWallpaper file in the wallpaper theme directory, excluding changes made by explorer.exe. This detection leverages the Endpoint.Processes and Endpoint.Filesystem data models to correlate process activity with file modifications. This activity is significant as it may indicate an adversary attempting to deface or change the desktop wallpaper of a targeted host, a tactic often used to signal compromise or deliver a message. If confirmed malicious, this could be a sign of unauthorized access and tampering, potentially leading to further system compromise or data exfiltration.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Impact | T1491 Defacement |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 1 | Process creation |
| Sysmon | 11 | FileCreate |
Stages and Predicates
Stage 1: tstats
tstats WHERE Processes.process_path!="*\\Windows\\Explorer.EXE" BY _time, Processes.action, Processes.dest, Processes.original_file_name, Processes.parent_process, Processes.parent_process_exec, Processes.parent_process_guid, Processes.parent_process_id, Processes.parent_process_name, Processes.parent_process_path, Processes.process, Processes.process_exec, Processes.process_guid, Processes.process_hash, Processes.process_id, Processes.process_integrity_level, Processes.process_name, Processes.process_path, Processes.user, Processes.user_id, Processes.vendor_product
Stage 2: search
search
Stage 3: rename
rename
Stage 4: join
join type=inner (...)
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 |
|---|---|---|
Filesystem.file_path | eq |
|
Processes.process_path | ne |
|