Category: Security

Software defined radio talks from Defcon 23

Defcon is a yearly conference that focuses on computer security and hacking talks. In recent years they have included a “Wireless Village” section that includes talks about all things wireless. This year there were several interesting talks related to Software Defined Radio in some way. Recently some of these talks have been uploaded to YouTube and below we present the ones we have found – let us know if we missed any interesting ones.

Balint Seeber – SIGINT & Blind Signal Analysis w/ GNU Radio & SDR

The workshop will cover many common techniques used to reverse engineer the physical layer of a wireless communications system:

– Blind signal analysis on a signals re-broadcast from a satellite transponder: modulation type, order, symbol rate, error correction,scrambling, differential coding, visualization

– Applying auto-correlation to interesting signals on the HF band: RADAR, OFDM, symbol timing

– Frequency hopping: wide-band, real-time spectrum visualization

All with GNU Radio!

DEF CON 23 - Wireless Village - Balint Seeber - SIGINT & Blind Signal Analysis w/ GNU Radio & SDR

Tim Oshea – GNU Radio Tools for Radio Wrangling/Spectrum Domination

An overview of modern tools available in GNU Radio and the greater GNU Radio ecosystem for building, testing, inspecting and playing with radio system physical layers in gory detail.

DEF CON 23 - Wireless Village - Tim Oshea - GNU Radio Tools for Radio Wrangling/Spectrum Domination

Michael Calabro – Software Defined Radio Performance Trades & Tweaks

This workshop is targeted at new and experienced software defined radio (SDR) operators, developers, and enthusiasts seeking a better end-to-end system understanding, and anyone looking to maximize their SDR’s performance. Commercially available SDRs (e.g. USRPs, RTL-SDRs, BladeRFs, etc) are commonly used to fuzz wireless interfaces, deploy private cellular infrastructure, conduct spectrum surveys, and otherwise interact with a wide variety of custom and commercial devices. This workshop focuses on the key parameters and performance drivers in SDR setup and operation that elevate these common platforms to the level of fidelity required to interact seamlessly with commercial devices and networks.

The workshop will begin by surveying different SDR hardware architectures and summarizing the performance tradespaces of several of SDR applications (e.g. collection/survey/transmit). Then the workshop will break down into three main content focuses:

Understanding SDR Hardware: Breakdown common RF frontend and receiver architectures. Identify and derive key performance parameters, and when they will bound performance. Topics covered will include: Noise figure calculation, internal amplification, Frequency selectivity, external RF chains, and noise sources.

Understanding SDR Platform Objectives: Collection, transmission, surveying, and other applications, each present unique challenges to SDRs and will be limited by different dimensions of SDR processing and/or setup configuration. Topics covered include: real-time processing, host buffering, sampling, guard-intervals, framework selection (GRC vs REDHAWK vs MATLAB vs custom), and frequency and time domain signal representation.

Optimizing and Improving Performance: Now that the hardware and platform trade space have been characterized, how do attendees meet and exceed the performance requirements of their application? We will present specific examples for several common platforms (RTL-SDR and USRP). Topics covered will include clock selection, ADC dynamic range, FPGA/SoC offloading, RFIC configuration, CIC filters, sampling, DC biases, antenna selection & pointing, host buffering / processing, and cost-performance trades.

DEF CON 23 - Wireless Village - Michael Calabro - Software Defined Radio Performance Trades & Tweaks

Karl Koscher – DSP for SDR

The barrier to entry in software-defined radio is now almost non-existent. Wide band, receive-only hardware can be obtained for as little as $10, and tools like gqrx and SDR# make it extremely easy to get started listening to signals. However, there is a steep learning curve graduating from an SDR script kiddie to developing your own SDR tools. In this talk, I’ll cover the basic theory behind software-defined radios digital signal processing, and digital communication, including I/Q samples, FIR filters, timing and carrier recovery, and more.

DEF CON 23 - Wireless Village - Karl Koscher - DSP for SDR

In addition to these Wireless Village talks there was also an interesting talk by Samy Kamkar in which explains how he uses SDR in his vehicle security research.

Samy Kamkar – Drive it like you Hacked it: New Attacks and Tools to Wireles

Gary Numan said it best. Cars. They’re everywhere. You can hardly drive down a busy freeway without seeing one. But what about their security?

In this talk I’ll reveal new research and real attacks in the area of wirelessly controlled gates, garages, and cars. Many cars are now controlled from mobile devices over GSM, while even more can be unlocked and ignitions started from wireless keyfobs over RF. All of these are subject to attack with low-cost tools (such as RTL-SDR, GNU Radio, HackRF, Arduino, and even a Mattel toy).

We will investigate how these features work, and of course, how they can be exploited. I will be releasing new tools and vulnerabilities in this area, such as key-space reduction attacks on fixed-codes, advanced “code grabbers” using RF attacks on encrypted and rolling codes, and how to protect yourself against such issues.

By the end of this talk you’ll understand not only how vehicles and the wirelessly-controlled physical access protecting them can be exploited, but also learn about various tools for car and RF research, as well as how to use and build your own inexpensive devices for such investigation.

Ladies and gentlemen, start your engines. And other people’s engines.

Samy Kamkar is a security researcher, best known for creating The MySpace Worm, one of the fastest spreading viruses of all time. He (attempts to) illustrate terrifying vulnerabilities with playfulness, and his exploits have been branded:

“Controversial”, -The Wall Street Journal
“Horrific”, -The New York Times
“Now I want to fill my USB ports up with cement”, -Gizmodo

He’s demonstrated usurping typical hardware for surreptitious means such as with KeySweeper, turning a standard USB wall charger into a covert, wireless keyboard sniffer, and SkyJack, a custom drone which takes over any other nearby drones allowing them to be controlled as a massive zombie swarm. He’s exposed issues around privacy, such as by developing the Evercookie which appeared in a top-secret NSA document revealed by Edward Snowden, exemplifying techniques used by governments and corporations for clandestine web tracking, and has discovered and released research around the illicit GPS and location tracking performed by Apple, Google and Microsoft mobile devices. He continues to produce new research and tools for the public as open source and open hardware.

DEF CON 23 - Samy Kamkar - Drive it like you Hacked it: New Attacks and Tools to Wireles

Hak5: Reverse Engineering Radio Protocols with SDR and the Yardstick One

Over on YouTube the popular security and hacking themed channel Hak5 have created two videos together with Mike Ossmann (creator of the HackRF and Yardstick One) that give a good introduction and overview on reverse engineering unknown radio protocols. In the video they show how to use a SDR like the RTL-SDR or HackRF to initially capture the radio signal, and then how to use the Yardstick One to reverse engineer and recreate the signal. Using this process they reverse engineer the radio protocol for a wireless liquor cabinet lock.

The Yardstick One is a computer controlled wireless transceiver (but it is not an SDR). The Yardstick One understands many radio protocols by default and can be programmed in Python, lowering the learning barrier for reverse engineering signals.

Mike Ossmann has also been slowly releasing very detailed video tutorials about DSP and radio related topics. If you are interested in reverse engineering radio signals it is a very helpful series to watch.

Radio Hacking: Reverse Engineering Protocols Part 1 - Hak5 1913

Radio Hacking: Reverse Engineering Protocols Part 2 - Hak5 1914

Hak5: Hacking Wireless Doorbells and Software Defined Radio tips

On this weeks episode of Hak5, a popular electronics and hacking YouTube show, the presenters talk about reverse engineering and performing replay attacks on wireless devices such as a doorbell. They also talk about using the recently released Yardstick One which is a PC controlled wireless transceiver that understands multiple modulation techniques (ASK, OOK, GFSK, 2-FSK, 4-FSK, MSK) and works on multiple bands (300-348 MHz, 391-464 MHz, and 782-928 MHz), but is not a software defined radio.

Finally they discuss how to use the RTL-SDR and GQRX to stream received audio over a UDP network connection using netcat in Linux.

Hacking Wireless Doorbells and Software Defined Radio tips - Hak5 1910

If you are interested in the Yardstick one, Hak5 also uploaded two earlier episodes this month showing how to use the Yardstick one, and how to hack wireless remotes by using the RTL-SDR to do the initial reverse engineering, and then using the Yarstick One to do the transmitting.

How to begin hacking with the YARD Stick One - Hak5 1908

How to Hack Wireless Remotes with Radio Replay Attacks - Hak5 1909

Hacking GSM Signals with an RTL-SDR and Topguw

The ability to hack some GSM signals has been around for some time now, but the steps to reproduce the hack have been long and difficult to set up. Recently RTL-SDR.com reader Bastien wrote into us to let us know about his recently released project called Topguw. Bastien's Topguw is a Linux based program that helps piece together all the steps required in the GSM hacking process. Although the steps are simplified, you will still need some knowledge of how GSM works, have installed Airprobe and Kraken, and you'll also need a 2TB rainbow table which keeps the barrier to this hack still quite high. Bastien writes about his software:

So like I said my software can "crack" SMS and call over GSM network.

How ?

I put quotation marks in crack because my software is not enough to deciphered GSM itself. My software can make some steps of the known-plaintext attack, introduce by Karsten Nohl, and by the way, increase the time to decipher an SMS or call. I'll not explain here all the steps because they are long and tedious, but there is a lot of work done behind the Gui.

Actually my software can extract Keystream (or try to find some of them) from a capture file of GSM, or by sniffing GSM with a rtl-sdr device. Then you just have to use Kraken to crack the key and you're able to decipher sms or call.

Why ?

This hack is very interesting! With only a little receiver (rtl-sdr) and some hard-disk capacity (2Tb), everyone can try to hack the GSM. It's very low cost compare to other hack vector. Moreover the success rate is really great if you guess the Keystream correctly. So when I started to done this with my hands I though -> why don't try to make something to do this automatically.
This is how Topguw was born.

Topguw, I hope, will sensitize people about risk they take by calling or sending sms with GSM.

My software is currently in beta version but I did run several time and I got good results. Maybe better than something done by hand. But Topguw is made to help people who want to learn the hack. This is why several files are made to help GSM reverse-engineering.

Topguw can be downloaded from GitHub at https://github.com/bastienjalbert/topguw. Bastien has also uploaded a video showing his software in action. If you're interested in Bastiens YouTube channel as he plans to upload another video soon where he shows himself hacking his own GSM sms/call signals.

Topguw Proof of concept - GSM Hacking educational purpose

Of course remember that hacking into GSM signals is very illegal and if you do this then you must check the legality of doing so in your country and only receive your own messages or messages that are intended for you.

Update 27 Feb 2023: Note that this content is constantly being censored by video upload sites. If the above video is down, Bastien has uploaded links to alternative video upload sites on pastebin.

Controlling Siri and Google Now with a Yagi and USRP

Wired magazine have recently run a story that shows how French researchers have discovered a method for remotely controlling modern smartphones through an RF attack that targets the voice control functionality called Siri on the iPhone and Google Now on Android. The attack only works for phones that have voice commands enabled, and there must be a pair of microphone enabled headphones plugged in.

The attack is pretty simple in theory. It works by using a software defined radio to transmit a high power amplitude modulated CW signal that will be picked up by the microphone’s cable which acts like an antenna. The AM CW signal is modulated in such a way that the built in low pass filter in the microphone works as a demodulator and turns the signal into an audio voice command.

In their experiments they were able to use a USRP SDR, amplifier and directional Yagi antenna to cause a smartphone to load up their webpage. The same attack could probably be performed with a cheaper HackRF SDR. 

A talk by the researchers was uploaded to Google earlier this month and is shown below.

HIP15-TALK:You don't hear me but your phone's voice interface does

Reverse engineering a public parking electronic display to play Tetris

Recently we received an email from RTL-SDR.com reader @Ivoidwarranties about his latest project which involved using a HackRF to reverse engineer the RF protocol used by a public parking electronic display. Once reverse engineered @Ivoidwarranties used a XR-2206 monolithic function generator, hybrid RF amplifier and an Arduino to create a device that overrides the public parking display and plays a game of Tetris on it.

We don’t have any details on the HackRF reverse engineering side of things, but he has uploaded a video to YouTube showing the hack in action.

Real hacking of public parking electronic display

Video showing SMS Texts and Voice Calls being sniffed with an RTL-SDR

Over on YouTube user Osama SH has uploaded a video briefly showing the steps needed to use an RTL-SDR dongle to sniff some SMS text messages and voice calls made from his own phone. This can be done if some encryption data is known about the phone sending the messages, so it cannot be used to listen in on any phone – just ones you have access to. In the video he uses Airprobe and Wireshark to initially sniff the data, and find the information needed to decode the text message. Once through the process he is able to recover the SMS message and some voice audio files.

Reverse Engineering Wireless Mobile Traffic Lights with an RTL-SDR

When roadworks suddenly appeared on Bastian Bloessl’s girlfriends street the workers put up a set of automated wireless traffic lights to control the flow of traffic during the works. Seeing these lights, Bastian quickly grabbed his RTL-SDR dongle and got to work on reverse engineering the status telemetry signals transmitted by these lights.

Wireless traffic lights reverse engineered with an RTL-SDR
Wireless traffic lights reverse engineered with an RTL-SDR

Bastian discovered two signals at around 170 MHz which corresponded to two pairs of lights. By analyzing the signal in Baudline and Audacity he discovered that the signal was AFSK1200 modulated between 1200Hz and 2400Hz. He then created a simple GNU Radio program which was able to output the frame bit data. After some analysis he was able to make sense of the structure and create a simple web interface that visualized the data as virtual traffic lights on his PC. The YouTube video below shows the signal and his RTL-SDR decoding software in action.

It seems that the telemetry is unencrypted, however we would assume that the control signals are encrypted.

Traffic Lights + GNU Radio + RTL SDR