Search

Hacking GSM: Building a Rogue Base Station to Hack Cellular Devices



Introduction


A rogue base station (also called a dirt box or rogue BTS) is the use of a software-defined radio (SDR) to create a fake cell tower and a software implementation of a GSM/GPRS radio access network. The software typically used to power rogue BTS’ is YateBTS, which supports GSM850, EGSM900, DCS1800, PCS1900 GSM bands.


The purpose of creating a rogue base station in vulnerability research or penetration testing of cellular-capable IoT devices or embedded systems, such as telematics control units (TCUs) inside connected cars is to force an association of the device talking over GSM to associate to the rogue BTS instead of a legitimate cell tower. This is done in an attempt to capture, analyze, and in some cases, intercept and modify the transmission between the backend and the device in an attempt to control it to affect the confidentiality, integrity, or availability of the data transmitted to it.


Very little research has been published on how to build rogue BTS’ over the years, especially as it applies to performing penetration testing of connected cars. As a matter of fact, the last video created on it was by me in 2017. Now, three years later, much has changed, so much so that even a new BladeRF has been released by Nuand that supports 5G.


What’s unique about this series is not only will I walk you through setting up and configuring a rogue BTS using the BladeRF 2.0 Micro, but also how to perform a connected car penetration test using law enforcement vehicles as targets. Earlier this year, state law enforcement across multiple states requested me to perform a penetration test of their different vehicles, the Ford Intercepter, Dodge Charger, and Ford Explorer. The Las Vegas Police Department (LVPD) was kind enough to allow me to film the engagement so long as no badges were recording during the filming.


This documentary-style film will be released alongside the final article in this series. This article focuses on the configuration and installation of the BladeRF tools, YateBTS, and how to sniff the GSM packets traversing the local loopback interface for devices that associate to your rogue BTS.


The instructions in this article are for the installation and setup of the BladeRF 2.0 Micro. My setup uses the 2.0 Micro (A9) model. The BladeRF X40, the predecessor to the BladeRF 2.0 Micro supported 300 MHz to 3.8 GHz while the 2.0 Micro supports 47 MHz to 6 GHz.


The final article in this series will provide instructions on how to setup and install the BladeRF 2.0 Micro. In addition to hacking devices that have SIM chips in them and use GSM, the new frequency range of the 2.0 M