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”VCONN pin is connected to VBUS via a resistor. There are also diodes on the board”

A truly paranoid analyst would check that these things that look like a resistor or diode actually are resistors and diodes. That may not be easy, as they could contain a tiny cpu and a few bits of flash memory that change the behavior from “resistor” to something else after x power ups or, using an on-board real-time clock, at a given date, or that run in parallel to the resistor or diode. A simple RFID chip already could be somewhat of use to spies.

Even simpler, that “resistor” could contain a tiny microphone and a radio transmitter (getting reasonable audio quality and reasonable radio range likely would be a challenge, but that’s what big budgets are for).

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I used to think things like these were fun conspiracy theories for a slow afternoon. I remember seeing a guy who got Linux running on a spare ARM CPU on his SATA hard drive, thinking "that'd be a great place for a rootkit".

But didn't think much further of it as that can be a dark rabbithole to go down. Then Snowden leaks came out, and it turned out technology was an active, hostile and full scale warzone.

These are not unreasonable thoughts to have now. Even if you prove one of these fans is safe, it does not prove that an individual has not been targeted with a fan with a payload.

Also, don't discount the entire circuit being the bug. https://en.wikipedia.org/wiki/The_Thing_%28listening_device%...

Exactly. That's a fantastic tactic. Give out a thousand fans and have only 9 or 10 of them be compromised. A safe fan gets torn down by security researchers and declared vanilla, and those 9 or 10 targets believe their fans are safe to use.

Or even just fake the analysis outright. North Korea having someone at Cambridge, or at least being able to feed them a benign variant via an unnamed journalist, is not out of the question.

We can probably rule this out since the paper doesn’t conclude that North Korea is #1 and Bless Dear Leader

The workers' effort of dismantling the fan promoted the mass line consciousness and building of a vigorous cadre feeling in the whole army.

Yes. This is obvious but also counterintuitive. People forget that it's a long game and that malware (such as Stuxnet) is patient and penetrates gradually.

If you're a government operation trying to bug an electronic device, chances are you're certainly not going to have your bug revealed by a simple teardown like this. I've heard rumors of certain cases where current fluctuations in the VBUS rail caused by certain peripherals can be used to compromise the USB controller. Additionally, embedded components can be placed between PCB layers, making it essentially appear "invisible" without using an x-ray system.

There _was_ a government operation like this recently:

"Russia spied on foreign powers at last month’s G20 summit by giving delegations USB pen drives capable of downloading sensitive information from laptops" - https://www.telegraph.co.uk/news/worldnews/europe/russia/104...

And these are simple to do, see BadUSB and Rubber Ducky

I ordered some 2 pin RGB LEDs a few years back. They change color over time via some built in IC, but the crazy thing is that the IC is so small that you can't even see it. And it all fits nicely within a standard LED. I would imagine someone could even fit a similar IC within the traces of a circuit board and nobody would be able to tell.

All of the puzzles Henryk Gasperowicz makes are this sort of thing. They're fun to try to figure out even if you know the basic idea, as they're pretty much all analog circuits. EG: https://www.youtube.com/watch?v=WvXKSSmItls

Ha-ha... damn, this is so cool! Thanks for the pointer.

Does he ever explain how the tricks work?

He posts full schematics on his google+ page - https://plus.google.com/+HenrykGasperowicz

Here is the schematic for the 3LEDs & 0 switches video liked by GP - https://plus.google.com/photos/116398424278304767741/album/5...

I don't understand the electronics, but the logic is hidden inside the 9 volt battery connector.

The bit inside the 9 volt connector isn't really logic. The flip-flops and Schmitt trigger gates are just to generate square waves at 3 different frequencies. There's also a small power supply to drop the 9V down to 6.2V for the input of that, some comparators, and a bit of filtering.

The LEDs contain LC filters, tuned such that they'll light (visibly) when the appropriate frequency is applied. Touching the wire in different places creates a different parasitic load, which is detected by one of the comparators. That comparator then toggles the clock generator for the appropriate frequency, turning that LED off or on.

As with all of his circuits it's a brilliantly simple idea implemented in a ridiculously constrained space.

What I like is how it breaks down the model that most people had. Models simplify, but they also constrain and we need to always be cognizant of where the model stops.

Some people over train in model-space and are unable to make thoughts that occur outside of that universe.

This video of "Inside the RFID Stickers from a Chinese Cashier-less Store" (around 9:20 and again at 12:20) was a real eye-opener to me: https://www.youtube.com/watch?v=0QKrHi-G9WQ

http://spritesmods.com/?art=hddhack

> These are not unreasonable thoughts to have now

They weren't really unreasonable thoughts to have back then, they may have just seemed unreasonable.

You're absolutely right that it would be almost impossible to detect a malicious device in one of those components. But a few things come to mind:

1. If you're that paranoid, don't plug stuff in to your USB ports EVER.

2. If you're going to put a malicious device in this thing, connecting it to VConn isn't a good idea - since you'd have to be hoping that whatever you've plugged into is insecure at a hardware level in quite a specific way that there's no evidence of.

3. There seem to be easier ways to hack visitors to singapore - like getting physical access to their laptop.

> 3. There seem to be easier ways to hack visitors to singapore - like getting physical access to their laptop.

In the US, it's as easy as Customs giving you a choice: 1) sit in a room indefinitely or 2) let them take your device into another room for an hour or so. Definitely a case of this: https://www.xkcd.com/538/

I've zero intention of ever visiting the US (partially because of shit they pull like your post) however if for some (incredibly unlikely) reason it's absolutely unavoidable I'll not be taking any electronics with me at all or taking something cheap and cleanslate that will be binned when I get back - essentially I treat the US as having the same threat model to visitors as China - well done whoever thought up those policies.

> 1. If you're that paranoid, don't plug stuff in to your USB ports EVER.

If you''re that paranoid then is any consumer hardware safe these days? Almost undetectable hardware could be slipped into to just about any device and they're mostly manufactured in a country hostile to personal freedom or countries under their influence.

The future is probably riscv style open hardware but that will need to be combined with local fabrication facilities.

> The future is probably riscv style open hardware but that will need to be combined with local fabrication facilities.

The big question is whether RISC-V is open enough for such purposes.

Is this satire? Did you see the size of the resistors on that thing in fig 5?

But a resistor or doide only have two connectors. How could one possibly hide a tiny CPU or RFID chip inside with only those connectors? Two connectors would be the minimum to just power the chip up.

See https://en.wikipedia.org/wiki/1-Wire

"One distinctive feature of the bus is the possibility of using only two wires: data and ground. To accomplish this, 1-Wire devices include an 800 pF capacitor to store charge and power the device during periods when the data line is active."

You can buy devices that put an entire JVM inside a two-terminal component, of similar physical size.

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