This tutorial will introduce you to breaking devices by determining when a device is performing certain operations. It will break simple bootloaders which may otherwise seem 'secure' against password attacks. In particular this uses the excellent [http://jtxp.org/tech/tinysafeboot_en.htm TinySafeBoot] bootloader for AVR microcontrollers. The example uses an old release of TinySafeBoot, since newer releases do not have this vulnerability!