1. A virtual user authentication system, comprising: a computing platform comprising a virtual machine manager (VMM) communicatively coupled to a user operating system (OS) and a service OS, the VMM configured to receive keystroke input destined for an application executing on the user OS and communicate the keystroke input to the service OS, the keystroke input processed by the service OS; wherein the service OS is configured to determine whether the keystroke input is associated with a security sensitive credential; wherein the service OS is configured to generate arbitrary placeholder characters corresponding to characters of the keystroke input if the keystroke input is associated with a security sensitive credential; wherein the arbitrary placeholder characters are communicated to a virtual keyboard driver of the user OS.