Hacking Rolling Code Keyfobs

 

hacking-rolling-code

Most keyfobs out there that open cars, garage doors, and gates use a rolling code for security. This works by transmitting a different key every time you press the button. If the keys line up, the signal is considered legitimate and the door opens.

[Spencer] took a look into hacking rolling code keyfobs using low cost software-defined radio equipment. There’s two pars of this attack. The first involves jamming the frequency the keyfob transmits on while recording using a RTL-SDR dongle. The jamming signal prevents the receiver from acknowledging the request, but it can be filtered out using GNU Radio to recover the key.

Since the receiver hasn’t seen this key yet, it will still be valid. By replaying the key, the receiver can be tricked. To pull off the replay, GNU Radio was used to demodulate the amplitude shift keying (ASK) signal used by the transmitter. This was played out of a computer sound card into a ASK transmitter module, which sent out a valid key.

Hacking Radio Controlled Outlets

Decoding NRZ ASK

It’s no surprise that there’s a lot of devices out of there that use simple RF communication with minimal security. To explore this, [Gordon] took a look at attacking radio controlled outlets.

He started off with a CC1111 evaluation kit, which supports the RFCat RF attack tool set. RFCat lets you interact with the CC1111 using a Python interface. After flashing the CC1111 with the RFCat firmware, the device was ready to use. Next up, [Gordon] goes into detail about replaying amplitude shift keying messages using the RFCat. He used an Arduino and the rc-switch library to generate signals that are compatible with the outlets.

In order to work with the outlets, the signal had to be sniffed. This was done using RTL-SDR and a low-cost TV tuner dongle. By exporting the sniffed signal and analyzing it, the modulation could be determined. The final step was writing a Python script to replay the messages using the RFCat.

The hack is a good combination of software defined radio techniques, ending with a successful attack. Watch a video of the replay attack after the break.

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Using SDR to Read Your Smart Meter

meter_read_wide

[BeMasher] was dissatisfied with the cost of other solutions to read his smart meter, so he made a project to read it himself using an rtl-sdr dongle.

Using his hacking and reverse engineering skills along with a $20 RTL-SDR dongle, [BeMasher] wrote rtlamr to automatically detect and report the consumption information reported by smart meters within range. Though designed for his Itron C1SR, [BeMasher] claims that any electronic receiver transmitter (ERT) capable smart meter should work.

[BeMasher]‘s Itron C1SR smart meter broadcasts both interval data and standard consumption in the 915MHz ISM band using a Manchester encoded, frequency hopping spread spectrum protocol. [BeMasher] used the RTL-SDR dongle to do the signal capture and analysed the resulting signal in software afterwards. [BeMasher] did a great job of going through the theory and implementation of analysing the resulting data capture, so be sure to check it for an in-depth analysis.

If the RTL-SDR dongles are too limited for you taste, you might want to check out some hacker friendly SDRs with a little more punch.

From vacuum cleaner hacking to weather station reverse engineering

spectrum

[Spock] wanted to do a little reverse engineering of his Miele brand remote control vacuum cleaner, so he broke out his DVB-T SDR dongle to use as a spectrum analyser. Sure enough, he found a 433.83Mhz signal that his vacuum cleaner remote control was using, but to his surprise, he found a stray QAM256 signal when he expected an ASK  only one.

After a little detective work, [Spock] eventually tracked it down to a cheap weather station he had forgotten about. The protocol for the weather station was too compelling for him to go back to his vacuum cleaner, though. After downloading an rc-switch Arduino library and making a quick stop at his local radio shack to get a 433.92 radio receiver to decode the signal, he reverse engineered the weather station so he could digitally record the temperature output. The Arduino rc-switch library proved unable to decode the signal, but some Python work helped him get to the bottom of it.

With software defined radio becoming more accessible and common place, hacks like these are a nice reminder just how wired our houses are becoming.

Verifying A Wireless Protocol With RTLSDR

rtlsdr_nrf905_rtlizer

[Texane] is developing a system to monitor his garage door from his apartment. Being seven floors apart, running wires between the door and apartment wasn’t an option, so he turned to a wireless solution. Testing this wireless hardware in an apartment is no problem, but testing it in situ is a little more difficult. For that, he turned to software defined radio with an RTLSDR dongle.

The hardware for this project is based around a TI Stellaris board and a PTR8000 radio module. All the code for this project was written from scratch (Github here), making it questionable if the code worked on the first try. To test his code, [Texane] picked up one of those USB TV tuner dongles based around the RTL2832U chipset. This allowed him to monitor the frequencies around 433MHz for the packets his hardware should be sending.

After that, the only thing left to do was to write a frame decoder for his radio module. Luckily, the datasheet for the module made this task easy.

[Texane] has a frame decoder for the NRF905 radio module available in his Git. It’s not quite ready for serious applications, but for testing a simple radio link it’s more than enough.

Build a Cheap Airplane ADS-B Radio Receiving Tracking Station

airplane tracking with ADS-B radio receiving

Do you have commercial or general aviation flying over your home or near your home? Would you like to know more about these airplanes: identity, heading, speed, altitude and maybe GPS data along with even more information? Well then [Rich Osgood] has just the project for you and it’s not that expensive to set up. [Rick] demonstrates using a cheap USB dongle European TV tuner style SDR (software defined radio) tuner that you can get for under $30 to listen in on the Automatic Dependent Surveillance-Broadcast (ADS-B) 1090 MHz mode “S” or 978 MHz mode “UAT” signals being regularly transmitted from these aircraft.

He steps us through configuring the radio to use a better antenna for improved reception then walks through detailed software installation and set up to control the radio receiver as well as pushing the final decoded data to mapping software. This looks like a fascinating and fun project if you live near commercial airways. You won’t need a license for this hack because you’re only listening and not transmitting, plus these are open channels which are legal to receive.

There are some frequencies you are not legally allowed to eavesdrop on—private communications for residential wireless telephones and cellular frequencies to name just a few (Code of Federal Regulations Title 47, Part 15.9). So remember you do have to be careful and stay within legal frequencies even if your equipment is not restricted from such reception. Also note that just because you have a legal right to intercept conversations or data on some frequencies it could be illegal to publicly share the intercepted content or any details on the reception or decoding (just saying for the record).

We wonder if [Rick] could partner with [G. Eric Rogers] to upgrade [Eric’s] motorized telescope airplane tracking system to extrapolate the radio telemeter data into vector data so his Arduino can track without relying on a video feed. That merger might just get them both on a short TSA list.

Join us after the break for some extra informational links and to watch the video on setup, installation and usage of this cheap airplane tracking rig.

[Read more...]

Cracking GSM with RTL-SDR for Thirty Dollars

GSM

Theoretically, GSM has been broken since 2003, but the limitations of hardware at the time meant cell phone calls and texts were secure from the prying ears of digital eavesdroppers and all but the most secret government agencies. Since then, the costs of hardware have gone down, two terabytes of rainbow tables have been published, and all the techniques and knowledge required to listen in on cell phone calls have been available. The only thing missing was the hardware. Now, with a super low-cost USB TV tuner come software defined radio, [domi] has put together a tutorial for cracking GSM with thirty dollars in hardware.

Previous endeavours to listen in and decrypt GSM signals used fairly expensive software defined radios – USRP systems that cost a few thousand dollars a piece. Since the advent of RTL-SDR, the price of software defined radios has come down to about $30 on eBay, giving anyone with a Paypal account the ability to listen in on GSM calls and sniff text messages.

The process of cracking GSM first involves getting the TMSI – Temporary Mobile Subscriber Identifier – a unique ID for each phone in a certain cell. This is done by sending a silent SMS that will send back and acknowledgement an SMS has been received on the victim’s phone, but won’t give the victim any indication of   receiving a message.

From there, the attacker listens to the GSM signals in the cell, receiving bursts attached to a TMSI, and cracking the encrypted stream using 1.6 TB of rainbow tables.

[domi] put up a four-part tutorial series (part 1 above; part 2, part 3, and part 4) that goes over the theory and the actual procedure of cracking text messages and voice calls with a simple USB TV tuner. There are a few limitations; the attacker must be in the same cell as the victim, and it looks like real-time voice decoding isn’t yet possible. Cracking GSM for $30, though, that’s good enough for us.