There's nothing more dangerous than a bored engineer with a screwdriver, and hell hath no fury like a security researcher scorned. Last month, Security researcher Chaotic Eclipse (aka Nightmare-Eclipse) published two zero-day exploits, BlueHammer and RedSun, that made Windows Defender offer up system administrator privileges. They did this after their disclosure reports were allegedly dismissed by Microsoft's security team, resulting in a vendetta of sorts. Eclipse has now done it again, posting two new zero-day exploits, the first one an extremely serious BitLocker exploit named Yellow Key that grants full access to a locked drive. The second one, GreenPlasma, doesn't have a complete proof-of-concept (PoC), but it allegedly performs a local privilege escalation and gains system-level access. Given Eclipse's track record, it's a fair bet that it works as advertised.
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.
