IoT Penetration Testing Cookbook

Digging deeper into firmware

Let's first have a look at the bootloader. A bootloader's responsibility is to initialize RAM for volatile data storage, initialize serial port(s), detect the machine type, set up the kernel tagged list, load initramfs (initial RAM filesystem), and call the kernel image. The bootloader initializes hardware drivers via a Board Support Package (BSP), which is usually developed by a third party. The bootloader resides on a separate Electrically Erasable Programmable Read-only Memory (EEPROM), which is less common, or directly on flash storage, which is more common. Think of the bootloader as a PC's BIOS upon start up. Discussing each of the bootloaders' responsibilities in detail is beyond the scope of this book; ...