Conference:  Defcon 31

Authors: Matthew Harris Student, Medford Vocational Technical High School, Noah Gibson, Scott Campbell, Zachary Bertocchi

2023-08-01

Who likes paying to ride the subway? Sure, you could hop the fare gates, but that can be athletically challenging and simply isn’t cool enough for our tastes. What’s a mischievous and miserly rider to do, then? Hack the fare system of course! In this talk we'll walk you through how we, four high school students and cybersecurity noobs became the first to fully reverse engineer Boston’s CharlieCard fare system and earn ourselves free rides for life… or at least until the system gets fixed, whichever comes first. We’ll start by exploring the trials and tribulations of exploring the hardware behind the CharlieCards. Next, we’ll dive into the emotional rollercoaster of reverse engineering the black box that is a transit card system older than us. We’ll then explain the process of disclosing our findings to a government agency without having to hire a legal team. Finally, we’ll show you a demo of some of the tools we made, including our own portable fare machine! By the end of our talk, regardless of whether you’re an avid RFID hackerman, or a complete noob, we’ll leave you with useful reverse engineering strategies, tips for working with a government agency, and if nothing else, a fun story.