Create Your Own Fitness Tracker Firmware

Dive into the world of fitness tracker firmware modification in this 25-minute conference talk from Recon 2018 Montreal. Explore the Fitbit ecosystem, including server, tracker, and smartphone app interactions. Learn about the reverse-engineering process of Fitbit Flex firmware, covering encryption libraries, BLE communication, proprietary protocol parsing, and accelerometer processing. Discover how to modify firmware through binary patching using the adapted Nexmon framework. Witness a live demonstration of wirelessly flashing custom firmware on a Fitbit Flex, understanding the intricacies of the proprietary protocol, encryption, and validity checks. Gain insights into newly published firmware modifications that enable raw accelerometer readings, all without requiring hardware teardown.