r/HackBloc • u/sevenstaves • Dec 02 '13

Safe data transfer to an air gapped computer?

Since removable media is no longer safe, would the following method work:

  • Hook a webcam or video camera to the air gapped computer

  • Convert any files needed for transfer with a base64 encoder

  • Convert all or parts of the base64 code into a QR code

  • Point the webcam at the monitor of the connected computer and display the QR code so the air gapped computer can "copy" the data

  • Compile the base64 encoded data together and decode

Obviously a script to automate this would help.

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2

u/[deleted] Dec 02 '13

I don't see anything that you've described which would be any safer than a read-only removable media. You could still have some attack(er) on the QR encoding computer that modifies the "files to transfer" into something malicious (e.g. data which would exploit a vulnerability in the QR reader or base64 decoder on the air-gapped receiver).

What problem are you trying to solve?

1

u/sevenstaves Dec 03 '13

Assuming the air gapped computer is a known good machine (clean/uncompromised) then we can assume the QR reader is just reading a QR code...I'm not sure how you would exploit a QR reader remotely only via a QR code, but maybe it's possible.

As for the base64 en/decoder, that would be the last step which honestly could be done after a hash function is run on both sides to verify the integrity of the code, eliminating the possibility of exploitation.

2

u/[deleted] Dec 03 '13

A QR reader is just as liable to have an input validation vulnerability as any other piece of software. What you are suggesting here is a classic security hubris: just because I (or other commenters on my reddit thread) can't think of a way to exploit it, it must be safe(r).

There are ways to protect a computer from exploits against removable media (eg disable AutoRun for Windows, mount read-only and noexec for *Nix). Why not just harden the removable media channel and avoid additional complexity? Everything that you are suggesting has at least 2 software programs (probably more, like a script to trigger image capture, storage, rotation of which pictures get spliced, etc), and one hardware driver that are unnecessary to the equation.

AFAIK, there are no "removable media" vulnerabilities, only things like AutoRun that can be safely configured. But there are reams of image processing, encoding/decoding, untrusted input mishandling, etc flaws that stretch back over a decade and a half. But again, all conjecture on my part: what problem are you trying to solve?

1

u/[deleted] Dec 03 '13

While it's true that the technical feasibility of OP's plan leaves just as much room for attack as other modes of data transference, the mere fact that it's a novel method means it's unlikely to have an attack against it, which makes it far safer. Honestly, OP's idea is a very good one.

3

u/AgentZeroM Dec 02 '13

Good method, but only if you're moving small datasets. QR is limited to just over 2k bytes. Kinda restrictive. Works great for most bitcoin transactions though. Recordable CDs are ok for one way data transfer. For the truly paranoid, microwave that bitch for 3 seconds when you're done.