Here’s how to install and start up an UltraVNC server from within an RDP session. This has been tested with UltraVNC 1.0.8 and a remote desktop session into a Windows XP Professional SP3 installation, but should work in other Windows / UltraVNC combinations as well.

  1. RDP into the target system, and install UltraVNC. Be sure to select the checkboxes for registering VNC as a service, and starting up the service at boot time.
  2. Set a VNC password for the currently logged in user by starting up the VNC server (Start > All Programs > UltraVNC > UltraVNC Server > Start UltraVNC Service), then entering a password when prompted
  3. Open up Regedit (Start > Run > regedit)
  4. Copy the HKEY_CURRENT_USER\Software\ORL\WinVNC3\Password entry’s current value
  5. Create a new binary value entry located at “HKEY_LOCAL_MACHINE\SOFTWARE\ORL\WinVNC3\Default\Password”. Paste in the value you copied in the previous step to this new entry’s value
  6. Reboot

That’s it! It may be possible to get VNC going without the reboot, but this is the combination that got a working installation going for me.