--[ Why Won't U Boot?

$ getent passwd rgreer
├─ name: Ryan Greer
└── org: REDLattice

Ryan is a security researcher at REDLattice in Virginia. Prior to this he was a Captain in the US Army at the 781st MI BN. His research interests are in embedded device security and modern vulnerability analysis.


Working with embedded Linux devices can be intimidating. Flash, serial, bootloaders, kernels, firmware... it all sounds very complicated. So complicated, in fact, that it can be difficult to know exactly what will break things. Sometimes, attempting to patch a firmware upgrade results in a "soft-brick" which is a device that won't boot due to a problem with the software. Other times, it is simply necessary to run firmware other than what was intended by the manufacturer. Understanding the boot process and relevant components is critical to solving these problems and many others.

The purpose of this talk is to discuss these topics and demonstrate that they aren't that complicated after all. This talk will cover a common open-source embedded bootloader, U-Boot, and common firmware-related activities such as extraction, flashing, and modification that can be accomplished through U-Boot. Attendees can expect to leave with a better understanding of embedded Linux boot processes and the confidence to tackle this type of challenge in the future.