Is this proof of a backdoor? It sure seems like it. With a USB and a few files you can find on Github, you can break Bitlockers encryption.
YellowKey can be triggered simply by merely copying some files to a USB stick and rebooting to the Windows Recovery Environment. We tested this ourselves, and sure enough, not only does it work, it bears all the hallmarks of a backdoor, down to the exploit's files disappearing from the USB stick after it's used once.
The process is dead simple: grab any USB stick, get write access to the "System Volume Information," and copy into it the "FsTx" folder and its contents. Shift+click Restart to get Windows to the recovery environment, but then switch to holding down the Control key and don't let go. The machine will reboot, and without asking any questions or showing any menus, will drop you in an elevated command line with full access to the formerly Bitlocked drive, without asking for any keys.
