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Sniffing and Decoding NRF24L01+ and Bluetooth LE Packets For Under $30 46

Posted by timothy
from the on-the-cheap dept.
An anonymous reader writes "I was able to decode NRF24L01+ and Bluetooth Low Energy protocols using RTL-SDR. As far as I can see, this is the first time NRF24L01+ is being decoded, especially considering the low entry price for the hardware. Given the extreme popularity of this transceiver, we are likely to see a wave of hackers attacking the security of many wireless gadgets, and they are likely to succeed as security is usually the last priority for hardware designers of such cheap gadgets. A lot of work has been done to decode bluetooth using dedicated hardware, and I am sure this software can be adapted to output the right format as input to existing Bluetooth decoders such as Wireshark."
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Sniffing and Decoding NRF24L01+ and Bluetooth LE Packets For Under $30

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  • by nobuddy (952985) on Tuesday January 21, 2014 @01:22PM (#46026743) Homepage Journal

    Who needs a keylogger when you can just pipe their output to your local machine directly?

    • by AmiMoJo (196126) * <mojo@@@world3...net> on Tuesday January 21, 2014 @02:02PM (#46027263) Homepage

      Good wireless keyboards and mice encrypt the data. Microsoft hardware does this, and I believe that at least some of it also uses Nordic chips.

      This isn't really a security vulnerability at all. It's like trying to argue that ethernet is insecure. It's a transport layer, the security comes higher up the chain at the application level. Individual devices may fail to do this, but the author of the blog post made no attempt to determine how many of the devices he claims he could see fit into this category.

  • As far as I can see, this is the first time NRF24L01+ is being decoded, especially considering the low entry price for the hardware.

    begin sarcasm:: It is either the first time or it is not the first time. There is nothing that makes it "especially" so. Your violation has been noted. You will be watched for further grammar/logic errors in the future. Tread carefully on Slashdot.

  • 1) dig a hole 30 feet deep, say, 10x10 feet.

    2) drop computer in.

    3) no wires, dammit, take those out.

    4) fill with concrete.

    5) place crew-served weapons on top 24x7 for eternity.

    that's the only way. it would also help to nuke the machine in a microwave for a minute first so all the chips are back to sand.

    • Someone digs in from miles away, steals the computer - you forgot to pour any concrete in before the computer, and even if you did they could take their time cutting through it - and you're completely oblivious to the crime. I'd put it in a glass box at the top of a greasy pole in the middle of the gun-toters.

      • by evilviper (135110)

        I'd put it in a glass box at the top of a greasy pole in the middle of the gun-toters.

        Then somebody drives up in a bucket-truck, wearing a high-visibility shirt with the city/county/state logo on it, and smiles at everyone passing by, while he robs you....

  • by gstoddart (321705) on Tuesday January 21, 2014 @01:40PM (#46026999) Homepage

    I've always suspected pretty much none at all, which is why I keep it turned off unless I really specifically need it -- that and it sucks battery life.

    So, what do the people who know the protocols say? Is Bluetooth a protocol with any actual security, or is it just a lame, wide-open security hole written by lazy people who don't care?

    • by plover (150551)

      The security is "adequate" for most people. However, it's not perfect: http://www.hackfromacave.com/p... [hackfromacave.com]

    • by Megol (3135005)
      The question could be answered by a search string shorter than your post - I'd suggest you'd learn to optimize.

      Yes BT supports encryption, or not. It depends on what is sent and how.

      • by gstoddart (321705)

        The question could be answered by a search string shorter than your post - I'd suggest you'd learn to optimize.

        I know how to use google there, skippy.

        But since Slashdot is most useful when we put these things into the comment threads, I opted for that.

        But, hey, you can feel free to continue to be a smarmy little wanker who thinks the rest of us don't know how to use search engines.

        Because, your "yes, maybe, sorta" adds nothing of value to the discussion.

    • by AmiMoJo (196126) *

      BTLE has minimal security. It is designed to be low power and low range, and most devices are transmit only. I suppose they were hoping that limited range and the transmit only nature of most devices would be enough to get away with extremely minimal security, but in practice users probably don't want other people to be able to monitor their heart rate sensor or send messages to their smart watch.

      • by Chelloveck (14643)

        users probably don't want other people to be able to monitor their heart rate sensor

        I should say not! Hell, if hackers can monitor your heart rate sensor they can get in and adjust it. Make your heart race until it explodes! This is why we need to restrict the transceiver technology this article talks about. Keep it in the hands of licensed professionals. It's just too dangerous to let hackers get anywhere near it.

        • by dfsmith (960400)
          You can adjust the heart rate of someone nearby by telling them a joke. ("Wenn ist das Nunstück git und Slotermeyer?", etc.)
        • by AmiMoJo (196126) *

          Did you read the bit about it being transmit only? It has no receiver, you can't send commands to it. Even if you could it doesn't have any control over your heart, it is just a sensor.

    • It used to suck battery on my older phones, but on my last 2 phones (current being Galaxy S4) it doesn't even register most of the time. Bluetooth is integrated into the same chip as wifi, so if you leave wifi on then it shouldn't really use any extra power.

      • by gstoddart (321705)

        Bluetooth is integrated into the same chip as wifi, so if you leave wifi on then it shouldn't really use any extra power.

        Well, I'm not really prepared to leave wifi on for well documented [slashdot.org] reasons.

        Wifi and Bluetooth are turned on only as needed -- anything else seems like a dumb idea.

        • by jodosh (1260096)
          That well documented reason is only an issue if you have your device try to join any open WiFi network. Why that is even an option is beyond me, but leaving WiFi on is not itself a problem.
    • by mpeg4codec (581587) * on Tuesday January 21, 2014 @03:22PM (#46028289) Homepage

      Hi, I'm a Bluetooth Security researcher [lacklustre.net]. My primary focus is on BLE for which I built a highly robust sniffer on the Ubertooth platform [sourceforge.net]. I have experience in other aspects of Bluetooth.

      TL;DR: Classic Bluetooth is very secure, BLE is secure under some circumstances. Even if you leave your Bluetooth on in discoverable mode, there isn't much an attacker can do to harm you barring bugs in your Bluetooth stack.

      Bluetooth is a well-designed protocol stack that takes security seriously in its design. Implementation quality (and bugs therein) varies from stack to stack. It's always a good idea to disable Bluetooth if you aren't using it, as is the case with any other remotely accessible feature.

      Classic Bluetooth has used Secure Simple Pairing (SSP) since 2.1 in 2007. This pairing mechanism is based on ECDH to provide perfect forward secrecy and is highly secure. There was one weakness discovered in the numeric entry pin mode [blackhat.com] in 2008 by Andrew Lindell. This mode is not commonly used in older devices and more recent devices do not implement it. It's effectively impossible for an attacker to sniff any data sent over Bluetooth with SSP.

      BLE has major weaknesses in its pairing protocol that I spoke about at BlackHat USA 2013 [blackhat.com] and other venues. For the most recent video see my presentation at USENIX WOOT 13 [usenix.org].

      In BLE, a passive eavesdropper who is present during pairing can recover the secret key used to encrypt all communications. This effectively makes the security worthless. However, if the attacker is not present during pairing then the encryption is very effective. It uses AES-CCM and doesn't have any major flaws in the design. AES-CCM is used in WPA2-AES; it's well-established and has no major shortcomings.

      Finally, some Bluetooth stack implementations have bugs. I've found remote bugs in one major vendor's stack.

  • by tlambert (566799) on Tuesday January 21, 2014 @02:03PM (#46027289)

    Uh, Nordic documents its over the air protocols...

    https://devzone.nordicsemi.com... [nordicsemi.com]

    • by Chelloveck (14643)
      This reminds me of a 2600 article I saw way back in the day. The authors had painstakingly reverse engineered the analog cellular system control channel. I read the article, saw the trouble they went through and where they drew the wrong conclusions, and thought to myself, "Guys, you know you can just go buy the actual spec, right?"
  • why so much complexity to decode a standardized protocol.

    Just to be clear. This is no security breach this is just a very complicated way to set up a demodulator. All that happens is that this guy pulls out the bits from the on-air datastream. Any reasonably configurable 2.4GHz band RF device capable of 1Mbit GFSK would be able to do this.

    BLE uses AES to encrypt the channel, so to compromise security you need to extract the key. You either need to compromise the initial key exchange, or you need to perform

    • by plover (150551)

      If you can force errors to cause the user to perform another key exchange that you can compromise, it's still game over. Never pair your Bluetooth devices in an untrustworthy location, especially if they "used to work".

  • RTFA, everyone... (Score:5, Informative)

    by Shoten (260439) on Tuesday January 21, 2014 @02:19PM (#46027527)

    He isn't decrypting the traffic; he's just able to pull the raw packets from the air and express then, still encrypted, as data. And for BTLE, he isn't even able to do that, as he can't manage the frequency agility. So he isn't even seeing the encrypted data, just the BT advertisements...which you can already do with a variety of tools (bluetoothscan, bluelog, etc.) and a cheap BT dongle with greater range than the setup he has put together.

    It's a clever kluge for capturing and reading 2.4 GHz traffic with a sub-2.2 GHz device on the cheap but it's not really meaningful from a security perspective.

    • I built a BLE sniffer on Ubertooth [sourceforge.net] which does capture traffic on BLE data channels. Also I wrote a tool that can crack the pairing protocol and decrypt the data [lacklustre.net].

      It is more expensive than the sniffer in the article ($120) but very robust. I achieve the requisite frequency agility by handling timing in real-time on the microcontroller on the dongle.

  • This is not a hack. This is a kludge that is more expensive and way more complicated than any competent person could have done by reading the datasheet and using the device as it was intended. I know this because I use it this way on a project I'm working on right now.

    There is no security on the nRF24l01+. It transmits in the clear and describes how it does so in it's publicly and freely available datasheet.

    The nRF24l01+ data has been decoded millions of times - by other nRF24l01+ devices. If you just buy o

  • by Bender_ (179208) on Tuesday January 21, 2014 @04:36PM (#46029105) Journal

    This is a nice hack, but in the end, he just build a receiver for the 2.4Ghz band. Big deal.

    There has been a much nicer hack to convert a nRF24L01 into a promiscuous listening device:

    http://travisgoodspeed.blogspo... [blogspot.de]

    This achieves a very similar goal, but much cheaper.

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