Unified Extensible Firmware Interface or UEFI, is the result of a common effort from several manufacturers and industry stakeholders based on an initiative from Intel. It is a new software component or ‘middleware’ interposed between the hardware and the operating system designed to replace the traditional aka old BIOS. This presentation is a study of the overall architecture of UEFI from a security point of view with a focus on a bootkit implementation for Windows 8 x64 which exploits the UEFI firmware: Dreamboot. Dreamboot has two specific payloads: Privilege escalation and Windows local authentication bypass. DreamBoot comes in the form of a bootable ISO, to use preferably as part of a physical attack (i.e. when the attacker has physical access to the machine peripherals: DVD or USB ports). It is also fully functional in virtualized environments like VMWare Workstation or ESX. The presentation also describes how to develop for UEFI platforms using Tianocore SDK and the new security risks its deployment implies. The Windows boot process and its evolution from BIOS to UEFI implementation will be covered and all bootkit implementation details explained.