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Intro to SDR and RF Signal Analysis

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Re: Intro to SDR and RF Signal Analysis

#31

Post by amenghra »

problems wrote: post #20
crispyambulance wrote: post #18

Earlier quoted context omitted.

Assuming you could read signals to/from a key-fob/HID-card, isn't there some encryption involved that would prevent merely repeating the signal to "clone" a key-fob?

You can't clone it as many do challenge response but you can relay it - check out NFCgate for example. This would allow you to say, hold one device to the reader and one against someone's pocket to open a door. Or to share an NFC transit pass between multiple people over the internet.

Search for "distance bound protocol" if you want to read about current crypto research to prevent relaying.

Re: Intro to SDR and RF Signal Analysis

#32

Post by ryandrake »

forg0t_username wrote: post #6

If you want to dabble for _cheap_ with SDR, the RTL-SDR [1] is a It allows to listen to FM radio, decode most 433MHz devices (weather stations), car keys signals, and even NOAA weather satellites [2] with a DIY antenna [3]. [1] https://osmocom.org/projects/sdr/wiki/rtl-sdr [2] http://www.rtl-sdr.com/rtl-sdr-tutorial-receiving-noaa-weath... [3] http://tinhatranch.com/how-to-build-a-qfh-quadrifilar-helix-...

As an aviation enthusiast, I've got a Raspberry Pi in my attic hooked up to two RTL-SDR radios, each connected to homemade antennas mounted on my roof (one VHF to listen to airband transmissions and the other receiving ADS-B[1]). No signal processing required--both are pretty easily achieved by just cobbling together existing open source packages. Also have a GPS receiver on the roof so that Raspberry Pi is also a stratum-1 NTP time server[2]. But that one's not using an SDR. Fun hobby.

EDIT: Added links I found helpful, for the curious:

1: http://www.rtl-sdr.com/adsb-aircraft-radar-with-rtl-sdr/

2: http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

Re: Intro to SDR and RF Signal Analysis

#34

Post by anonymous_iam »

Anyone know the story behind why baudline hasn't been updated in seven years? The site has promised a beta version with some highly desirable features for a LONG time, but nothing. Also, since it's closed source, there's nothing we can do but hope and wait (unless someone were to start an open source equivalent project).

Re: Intro to SDR and RF Signal Analysis

#35

Post by problems »

amenghra wrote: post #31
problems wrote: post #20

Earlier quoted context omitted.

You can't clone it as many do challenge response but you can relay it - check out NFCgate for example. This would allow you to say, hold one device to the reader and one against someone's pocket to open a door. Or to share an NFC transit pass between multiple people over the internet.

Search for "distance bound protocol" if you want to read about current crypto research to prevent relaying.

There are some interesting attempts at these protocols but most of them rely on multiple powered devices, not induction powered smartcards which inherently adds delay and not necessarily predictable delay.

No one has a proven system for doing this in today's smartcards to my knowledge. Though there is some research which promises this may be possible in the future.

Even those proximity car locks do a horrible job of distance bounding - many of them do it off RF level which means an attacker merely needs an amplifier to steal your car - and that offers an almost optimal situation for the application. So I think we'll probably see it there before smart cards. Maybe the timers necessary make this cost prohibitive though. I'm not in a position to say one way or the other.

Re: Intro to SDR and RF Signal Analysis

#36

Post by agumonkey »

forg0t_username wrote: post #6

If you want to dabble for _cheap_ with SDR, the RTL-SDR [1] is a It allows to listen to FM radio, decode most 433MHz devices (weather stations), car keys signals, and even NOAA weather satellites [2] with a DIY antenna [3]. [1] https://osmocom.org/projects/sdr/wiki/rtl-sdr [2] http://www.rtl-sdr.com/rtl-sdr-tutorial-receiving-noaa-weath... [3] http://tinhatranch.com/how-to-build-a-qfh-quadrifilar-helix-...

I heard of dvbt USB that could be used as sdr interface. I just wonder if the dvbt support under Linux is OK.

Re: Intro to SDR and RF Signal Analysis

#37

Post by anonymous_iam »

wonderous wrote: post #19

Beside HackRF One, I've been looking at LimeSDR. Are there any other comparable options?

BladeRF is pretty cool. It doesn't have quite the frequency range of HackRF, but it's full duplex, and uses 12-bit ADC/DAC (vs. HackRF's 8-bit ones). Also it uses USB 3 so the bandwidth is not limited to 20MHz. (I think it's around 40MHz.)

Re: Intro to SDR and RF Signal Analysis

#38

Post by bigiain »

audi100quattro wrote: post #12
pentestercrab wrote: post #3

Earlier quoted context omitted.

There is also meetup groups in San Francisco [1] and Melbourne (Australia) [2]. [1] https://www.meetup.com/en-US/Cyberspectrum/ [2] https://www.meetup.com/en-US/Cyberspectrum-Melbourne/

Thanks for posting links to the videos and the meetup group, would've joined it years ago if I'd known about it. Quick question, anything radar related in the videos?

Have you seen this: http://www.rtl-sdr.com/passive-radar-dual-coherent-channel-r...

I can't find the link here right now, but there's some more recent work that's doing that without needing the two clock synced receivers too...

Re: Intro to SDR and RF Signal Analysis

#39

Post by awqrre »

wyldfire wrote: post #27
awqrre wrote: post #24

Earlier quoted context omitted.

You can also track your neighbors' energy usage by decoding their smart meter transmissions (around here, they transmit about every minute). https://github.com/bemasher/rtlamr I can read about 40 smart meters from inside my home using the antenna that comes with it.

Is there an easy way to confirm which one's yours? Serial number visible from the exterior of the meter e.g.?

yes, the serial number is printed on the outside of every meter (so you can use a telescope to read your neighbor's meter serial number)

Re: Intro to SDR and RF Signal Analysis

#40

Post by gfv »

crispyambulance wrote: post #18
gfv wrote: post #9

Earlier quoted context omitted.

Not all RFID cards are created the same. Most RFID cards that are some kind of "smart" (i.e. contactless bank cards, subway tickets) conform to ISO/IEC 14443 standard that mandates the use of ~13.5MHz carrier to communicate between the reader and the card. This is "the NFC" as your phone understands it. Proximity cards used for door access usually have the 125kHz carrier compatible with the EM-Marin EM4100. No cell p…

Assuming you could read signals to/from a key-fob/HID-card, isn't there some encryption involved that would prevent merely repeating the signal to "clone" a key-fob?

Nope, an EM4100-compatible card (or a key fob) is just a 64-bit ROM with radio interface. You can read its value and replay it to a reader; the latter won't be able to tell the difference between the original card and your spoofed one.

Better (and more expensive) RFID tags may have an encrypted communication protocol.

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