Hacking_and_Penetration_Testing_with_Low_Power_Devices

Closing thoughts
237
For reasons mentioned early in this book, I do not recommend the Pi for penetration
tests. Spending more for a less powerful, less compatible, and less reliable device
seems like a bad idea to me. The techniques presented in this book could be used
if you insist on jumping on the Pi bandwagon.
ULTRALOW POWER WITH MICROCONTROLLERS
As was previously mentioned, my initial venture into developing penetration testing
hardware and operating systems for the Beagles was an extension of some USB
forensics work to devices that support high-speed USB. While the BeagleBone Black
is an extremely efficient and powerful computer that can be run from batteries, it is
extremely power hungry when compared to a microcontroller-based board.
The ATMega328P microcontroller found in some versions of the Arduino is a
commonly used chip. The ATMega328P requires only 0.2 mA of current at 1.8 V
(0.36 W) when operating at 1 MHz. In power save mode, this chip consumes only
0.75 mA (0.00075 mA) of current. By sleeping between tasks, a microcontrollerbased
device can operate for months or even years on a set of batteries.
The BeagleBone is overkill for what many people are doing with it. If you need to
push data, flip switches, push buttons, read sensors, run motors, or interface with
other hardware, but don’t need to do any serious computations, a microcontroller
can be a great solution. A set of microcontroller-based devices could easily be used
in a penetration test to feed information to Beagles for further processing.
FTDI (http://ftdichip.com) is a well-known manufacturer of USB-related chips. In
recent years, FTDI has begun to make microcontrollers that are capable of being used
as USB hosts and slaves. I have developed several devices based on their Vinculum II
microcontroller including a USB mass storage device forensic duplicator (https://
www.youtube.com/watch?v¼CIVGzG0W-DM), USB write blocker (https://www.
blackhat.com/html/bh-eu-12/bh-eu-12-archives.html), and USB impersonator (https://
defcon.org/html/links/dc-archives/dc-20-archive.html#Polstra). One limitation of the
Vinculum II is that it does not support high-speed USB. As of this writing, FTDI
has just announced a new microcontroller, the FT900, that supports high-speed
USB (http://www.ftdichip.com/Corporate/Press/FT900%20Press%20Release.pdf). Be
on the lookout for a possible sequel to this book on incorporating microcontrollers into
your penetration tests.
CLOSING THOUGHTS
This book represents several years of research and experimentation. It has introduced
you to a new way of performing penetration tests. My hope is that it has also stimulated
your imagination and will encourage you to do your own experimentation with
new techniques and devices of your own design.