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In my country you can buy a prepaid plan without ID. Lets say I buy two 4G dongles, connect both of them to a Rasperry Pi, pipe my connection trough the first dongle to the second dongle, hide the Pi in a public building ceiling and power it from the AC-line.

Assume that nobody find the Pi, the data is encrypted, no DNS or WebRTC leakage and I'm not using any of my personal accounts (eg. bank). Is there anyway that the ISP or someone else can find out where the data originally came from (IP address etc)?

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  • 3
    The "someone else" makes this difficult to answer, but my default stance for "can someone do X?" is almost always "yes, with enough effort". Now, are they going to spend that time, money, and effort? Maybe not. But that depends entirely on what you are doing and what your threat model is. – a CVn Dec 23 '16 at 12:42
  • It is unclear, what you mean with where the data comes from. Anonymity in the title hints that you may mean if they identify you as person (possibly without searching for the device), while hiding the Pi and asking about the IP sounds like you ask if the device can be found. – allo Apr 12 '18 at 9:33
  • If you did longer-range communication using DSSS (Direct Sequence Spread Spectrum) with a cryptographically secure sequence key and with multiple DSSS jammers to improve LPI/LPD (Low Probability of Interception/Detection), then it might provide some anonymity with an anonymity set within the radius of the transmitter's and jammers' range... it might work. It's quite overkill, even though it is what you would need to accomplish what you want. Yes, people have thought of this before. – forest Apr 12 '18 at 9:35
  • Hiding Information in Noise: Fundamental Limits of Covert Wireless Communication. – forest Apr 12 '18 at 9:39
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Summary: Don't do it.

Your question is mainly about anonymity. So I'll address that first:

  • You are talking about buying three pieces of hardware and two SIM cards. Each of these have an identification, which could possibly be tracked back to time and location of sale. At that point it could possibly be tied back to a CCTV recording or a card used to pay for the purchase.
  • There is also the possibility of a CCTV catching you in the act of hiding the device.
  • Finally you would want to communicate with this device. Both the ISP that you use to get in touch with this device as well as the ISP you use to establish connection to the device will likely have records indicating which pair of IP addresses are communicating.
  • There are plenty of ways in which the association between the two 4G dongles could be established. First of all you might have bought both at the same time, secondly the provider will know the approximate location of both dongles which happen to be the same and hardly ever changing.

As for the legality there are multiple reasons why what you are asking about might be illegal:

  • You might be violating trespassing laws when installing the device.
  • Even if you are allowed to be in that location, you might not be allowed to leave any of your personal belongings behind, when you leave that location again.
  • Hooking into an AC line without permission is almost certainly illegal and could potentially get you electrocuted.
  • You may be liable for the disruption caused by evacuation of the building and the bomb squad sent in to remove the device if the first person to find it does not have a clue what it is.

The reliability of such a device is unlikely to be good:

  • There is the possibility of the network access provided by your SIM cards to go through a CGN which means connecting to this device remotely can be difficult or even impossible.
  • If you were able to hide it in a public place there is the possibility that somebody else could find your device and modify and/or steal it.
  • If you ever return to the device in order to service it, there is no way of knowing who might be waiting there for you. (But they will probably suspect you to be a terrorist.)
  • The connectivity of either 4G dongle or the power supply could change in unanticipated ways with no warning.
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  • I have selled in my country these devices and plans. PoS-system read only EAN and if I don't put SIM to my phone and it is impossible to trace that back. You are right about legal issues. – Evus Dec 23 '16 at 14:12
  • And I'm pretty sure that ISP(or if I bought from two different provider) would not flag close or same location. Its aproximation based on dB and in appartment building can have about 100 none moving 3G/4G devices – Evus Dec 23 '16 at 14:16
  • CGN which means connecting to this device remotely can be difficult or even impossible this is not true with even a mild amount of know-how and automation you could work around this. – CaffeineAddiction Apr 12 '18 at 8:15
  • You should also mention that it'd likely be fairly trivial to locate both transmitters once you know the location of only one. Locating the "server" is trivial since it is not anonymous. The "client" follows. – forest Apr 12 '18 at 9:42
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I would need more details on your threat model to determine who would be looking, how competent they are, and how motivated they would be.

That being said, unless you are planning some light treason at a 3 letter agency, or your facility is otherwise obscenely security focused, there is a vanishingly small chance

  1. they would ever even find the hardware
  2. they would be motivated and/or willing to trace said hardware
  3. that hardware purchased carefully with cash, intermediaries, and/or pseudonymously would lead back to you via that route.

So, the technical aspect of something like this is not going to get you. You need to worry about:

  1. if discovered, will people assume it was the only nerd in the office who also happened to have a plausible motivation (investigations don't start with forensic analysis, they start by identifying means/motive/opportunity and work backwards)
  2. complacency: after 6 months of no one noticing, you will get lazy, sloppy, start accessing it from the same locations multiple times, then probably just doing it from home, at which point, the sheer number of tor network activity correlations would be enough to damningly implicate you, even if they can't prove it with 100% technical certainty.

When someone get's killed, they just go interview that persons spouse. When they find a spy device in the ceiling of your work, they're probably going to interview you.

Non-technical operational security considerations are almost always vastly under-attended to and usually the thing that bones people.

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  • complacency it will get you every time – CaffeineAddiction Apr 12 '18 at 8:16
  • I agree and have one thing to add: If they find the hardware, there may be some non-digital evidences like fingerprints on it. You may need to think like a criminal to avoid leaving any clues which can be used to identify you. – allo Apr 12 '18 at 9:37
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It seems to me that you are constructing a very small, private, unoptimized, and untested TOR network. Therefore, we can expand your question to: "Can I be deanonymized while using TOR?"

The answer to that is yes, using various techniques that are available to varying levels of sophisticated attackers, which have been detailed in the security news.

Since your system is less robust than TOR, we can assume that it will be correspondingly easier to find you. Your system is particularly vulnerable to prediction, because you just have 1 entry node and 1 exit node.

You seem to think that physically hiding the system will make it more secure, but (as kasperd points out), it only exposes you to unnecessary risk. The speed bump of "unknown server in an unknown location" isn't harder technically if the server is hidden, as opposed to in Bermuda.

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  • I would love link to paper or example, how TOR deanomyze techniques could apply on my device. (Without Social Engineering) – Evus Dec 23 '16 at 14:26
  • extremetech.com/extreme/… Your system will be very vulnerable to this style, because there is no traffic to mix with, and no delays to obscure the connection between the entry and exit. It would be trivial for the ISP / phone networks to connect this traffic to your source IP. – J Kimball Dec 30 '16 at 17:37
  • @JKimball if you setup a transparent proxy on it and publicly publish it as a transparent proxy ... you could get enough traffic to cover your tracks ... going to eat into your pre-payed budget though. – CaffeineAddiction Apr 12 '18 at 8:12
  • Do you mean a proxy/VPN? Tor is secure because it is a network, while the pi approach would be more like redirecting a single connection via a single hop on the pi. – allo Apr 12 '18 at 9:35

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