Writing simple BIOS bootloaders using NASM



The tutorial ends with a pointer to some BIOS interrupts. It should have mentioned Ralph Brown’s classic list.



memory loading


iPXE-Boot-Server: Setup iPXE to support both BIOS and UEFI

Step by step guide for how to build your own PXE boot server supporting both legacy BIOS and EFI hardare

Build your own PXE boot server

This article is a step by step guide for building your own PXE boot infrastructure which can be used to boot both legacy BIOS and EFI based hardware from network. There are many articles on the Internet for building PXE boot infrastructure however I found most of them does not work for EFI based hardware. I use iPXE as the boot image and dnsmasq as DHCP & TFTP server and I found it’s dead simple to setup those two software.






CheckBIOSDisk: Check uefi/legacy bios and gpt/mbr disk type for WinPE

This is a Win32 console application for Windows Preinstall Environment system. The gaol is checking PC uses UEFI BIOS (or with CSM) must ensures the disk type is GPT format, otherwise the legacy BIOS must using MBR format for disk layout. C++ code only does windows executing diskpart and reg commands and checks results to improve function, because requester is lazy and having lack knowledge on his job to design commands flow.


PS: Another tool by author:




Fruct20: UEFI BIOS and Intel ME attack vectors and vulnerabilities

UEFI BIOS and Intel Management Engine Attack Vectors and Vulnerabilities
Alexander Ogolyuk, Andrey Sheglov, Konstantin Sheglov
Saint Petersburg National Research University of Information Technologies, Mechanics and Optics
St. Petersburg, Russia

We describe principles and implementation details of UEFI BIOS attacks and vulnerabilities, suggesting the possible security enhancement approaches. We describe the hidden Intel Management Engine implementation details and possible consequences of its security possible discredit. Described breaches in UEFI and Intel Management Engine could possibly lead to the invention of “invulnerable” malicious applications. We highlight the base principles and actual state of Management Engine (which is a part of UEFI BIOS firmware) and its attack vectors using reverse engineering techniques.

From conclusion:
* Disable all SMM code (if possible by patching or other methods)
* Disable any external firmware components (PCI boot)
* Disable S3 Bootscript (after sleep mode)
* SMI transaction Monitor extensive usage (to find malicious SMI calls)
* Enable Secure Boot mode
* Enable BIOS password
* Extensive reverse engineering of vendor’s firmware samples to find and report vulnerabilities
* Code reviews (of open sourced UEFI based systems like Tiano-Core)






Intel seeks BIOS/UEFI Tools Developer

BIOS-UEFI Firmware Tools Engineer

As BIOS-UEFI Firmware Tools Engineer you will develop tools and scripts needed for build and test automation infrastructure that is the backbone of the the Continuous Integration process in Intel’s Data Center UEFI firmware BIOS team.[…]


PS: I need to figure out a way to get some swag/etc from jobs that’re filled via this blog. ;-(

PS: Intel HR: spaces in URLs is generally frowned upon.