Fail Of The Week: This Flash Drive Will NOT Self-Destruct In Five Seconds

November 25, 2023 by Dan Maloney 49 Comments

How hard can it be to kill a flash drive? Judging by the look of defeat on [Walker]’s face in the video below, pretty darn hard.

To bring you up to speed, and to give the “Mission: Impossible” reference in the title some context, it might be a good idea to look over our earlier coverage of [Walker]’s Ovrdrive project. It started way back in 2022 with the idea that some people might benefit from a flash drive that could rapidly and covertly render the data stored on it, err, “forensically unavailable.” This would require more than just erasing the data, of course, so [Walker] began looking at ways to physically kill a memory chip. First up was a voltage doubler to apply voltage much greater than the absolute maximum rating of 4.6 V for any pin on the chip. That corrupted some files on the flash chip, enough of a win to proceed to a prototype that actually succeeded in releasing the Magic Smoke.

But sadly, that puff of smoke ended up being a fluke. [Walker] couldn’t repeat the result, at least not with the reliability required by people for whom data privacy is literally a life-or-death matter. To increase the odds of a kill, he came up with an H-bridge circuit to reverse the polarity of the memory chip’s supply. Surely that would kill the chip, and from the thermal camera images, it sure looked promising. But apparently, even 167°C isn’t enough to forensically disable the chip, which kind of makes sense from the point of view of reflow survivability.

What’s next for [Walker]? He says he’s going to team up his overvoltage and reverse-polarity methods for one last shot, but after that, he’s about out of reasonable options. Sure, a thermite charge or a vial of superacid would do the trick, but neither is terribly covert. If you’re going to go that way, you might as well just buy a standard flash drive and throw it in the microwave or a blender. And we need to remember that this may be something the drive’s owner needs to do with jack-booted thugs kicking in the door, or possibly at gunpoint. It wouldn’t do to be too conspicuous under such circumstances. That’s why we like the “rapid power cycling” method of triggering the drive’s self-destruct sequence; it could easily be disguised as shaking hands in a stressful situation.

Who knew that memory chips were this robust? Kudos to [Walker] for getting the project as far as he did, and we’re still rooting for him to make it work somehow.

Continue reading “Fail Of The Week: This Flash Drive Will NOT Self-Destruct In Five Seconds” →

Self-Destructing USB Drive Releases The Magic Smoke

March 1, 2023 by Tom Nardi 52 Comments

There were some that doubted the day would ever come, but we’re happy to report that the ambitious self-destructing USB drive that security researcher [Walker] has been working on for the last 6+ months has finally stopped working. Which in this case, is a good thing.

Readers may recall that the goal of the Ovrdrive project was to create a standard-looking flash drive that didn’t just hide or erase its contents when accessed by an unauthorized user, but actively damaged itself to try and prevent any forensic recovery of the data in question. To achieve this, [Walker] built a voltage doubler circuit into the drive that produces 10 volts from the nominal 5 VDC coming from the USB port. At the command of an onboard microcontroller, that 10 V is connected to the circuit’s 3.3 V rail to set off the fireworks.

Early attempts only corrupted some of the data, so [Walker] added some more capacitance to the circuit to build up more of a charge. With the revised circuit the USB controller IC visibly popped, but even after it was replaced, the NAND flash was still unresponsive. Sounds pretty dead to us.

Unfortunately, there’s still at least one issue that’s holding back the design. As we mentioned previously, [Walker] was having trouble getting the computer to actually acknowledge his homebrew drive had any free space available. It turns out that the SM3257EN USB controller IC he’s using needs to be initialized by some poorly documented Windows XP software, which might not be such a big deal if the goal was just to build one of them, but could obviously be a hindrance when going into production.

He hopes further reverse engineering will allow him to determine which commands the XP software is giving to the IC so that he can duplicate them in a less ancient environment. Sounds like a job for Wireshark to us — with any luck he should be able to capture the commands being sent to the hardware and replay them.

While we can understand some readers may have lingering doubts about the drive’s spit-detection authentication system, it’s clear [Walker] has made some incredible progress here. This project demonstrates that not only can an individual spin up their own sold state storage, but that should they ever need to, they can also destroy it in an instant.

Retrotechtacular: Understanding A Voltage Doubler

August 13, 2013 by Mike Szczys 28 Comments

This very stern looking gentleman is about to explain how voltage doubles work in a plodding, yet satisfyingly thorough manner.

We’re not certain when this US Air Training Command video was produced. Obviously it was used to train servicemen who were responsible for keeping electronics running during war time. We’re glad for that, as they really found just the right balance to present a concept that required some knowledge, but is approachable for even the most basic of new electronics hackers.

The demonstration board shown on the right is the voltage circuit highlighted in the lesson. Here the pointing stick is being used to trace out the circuit function during one phase of the input transformer. The capacitor/diode pairs rectify the voltage, with the capacitors discharging in ~~parallel~~ series to double the output voltage. But how does the variable load (RL) affect the output? This is demonstrated under several different conditions using an oscilloscope to illustrate the change.

The discussion of how the diodes work reminded us of a modern tutorial we just ran across this weekend. It’s a bit bizarre, but explains the PN junction in a different way than we’re accustomed to. In this case you will already need to be familiar with how semiconductors work to understand the presentation.

Both clips can be found below the jump.

Continue reading “Retrotechtacular: Understanding A Voltage Doubler” →

Making A 12V Bulb Work In A 6V Socket

March 27, 2013 by Mike Szczys 28 Comments

12v-led-in-6v-socket

This is something of a square peg in a round hole type of problem. [Kiel Lydestad] has been riding a vintage Moped around. You know, a motorcycle that can be pedaled like a bike. He of course wants to keep the thing looking stock, but also needs it to be fully functional. Enter this light bulb replacement project. His brake light needed a new bulb, and he managed to make this 12V LED bulb work in the 6V socket.

An LED is a really great choice for this application since the Motobécane Moped uses a magneto generator to power the lights. It won’t pull much current, but it did need modification to run from half as much voltage. [Kiel] mentions that it may have been possible to crack open the LED tower and adjust the current limiting circuit inside, but he felt it was easier to just add this voltage doubling circuit. He assembled the components in a way that still allows them to fit in the metal base of the bulb.