Private Browsing Proxy

On Windows, Firefox ships with a small binary that always launches firefox.exe in Private Browsing mode (private_browsing.exe). Its sole purpose for existing is to allow Private Browsing shortcuts to have their own Visual Elements. This is most notably seen when pinning a Private Browsing shortcut to the Start Menu – Visual Elements are used for the icon there rather than the shortcut’s icon.

In addition to always passing -private-window, private_browsing.exe will forward any other command line arguments given to it to firefox.exe. It will also forward shortcut information from the Windows STARTUPINFOW structure to ensure that Firefox knows how it was started.