Cyber security

CrScreenshotDxe – A UEFI DXE Driver For Easy BIOS Setup And UEFI Screenshots

This DXE driver tries to register keyboard shortcut (LCtrl + LAlt + F12) handler for all text input devices.

The handler tries to find a writable FS, enumerates all GOP-capable video devices, takes screenshots from them and saves the result as PNG files on that writable FS.

The main goal is to be able to make BIOS Setup screenshots for systems without serial console redirection support, but it can also be used to take screenshot from UEFI shell, UEFI apps and UEFI bootloaders.

To start the driver, you can either:

  • Integrate it into DXE volume of your UEFI firmware using UEFITool or any other suitable software (don’t forget a DepEx section to prevent too early start)
  • Add it to an OptionROM of a PCIe device (will try it once I have a device needed)
  • Let BDS dispatcher load it by copying it to ESP and creating a DriverXXXX variable
  • Load it from UEFI Shell with load command

Build

It’s a normal EDK2-compatible DXE driver, just add it to your package’s DSC file to include in the build process.

Usage

Load the driver, insert FAT32-formatted USB drive and press LCtrl + LAlt + F12 to take screenshots from all GOP-compatible graphic consoles available at the moment.

To indicate it’s status, the driver shows a small colored rectangle in top-left corner of the screen for half a second.

Rectangle color codes:

  • White – driver is loaded
  • Yellow – no writable FS found, screenshot is not taken
  • Blue – current GOP is pitch black, screenshot is not taken
  • Red – something went wrong, screenshot is not taken
  • Green – screnshot taken and saved to PNG file
Varshini

Varshini is a Cyber Security expert in Threat Analysis, Vulnerability Assessment, and Research. Passionate about staying ahead of emerging Threats and Technologies.

Recent Posts

Nmap cheat sheet for beginners

Nmap (Network Mapper) is a free tool that helps you find devices on a network,…

1 day ago

Understanding the Model Context Protocol (MCP) and How It Works

Introduction to the Model Context Protocol (MCP) The Model Context Protocol (MCP) is an open…

1 week ago

The file Command – Quickly Identify File Contents in Linux

While file extensions in Linux are optional and often misleading, the file command helps decode what a…

1 week ago

How to Use the touch Command in Linux

The touch command is one of the quickest ways to create new empty files or update timestamps…

1 week ago

How to Search Files and Folders in Linux Using the find Command

Handling large numbers of files is routine for Linux users, and that’s where the find command shines.…

1 week ago

How to Move and Rename Files in Linux with the mv Command

Managing files and directories is foundational for Linux workflows, and the mv (“move”) command makes it easy…

1 week ago