3-D printer building something

Explosive technology and 3D printers: a history of deadly devices

Hackers: They’ll turn your computer into a BOMB!

“Hackers turning computers into bombs” is a now legendary headline, taken from the Weekly World News. It has rather set the bar for “people will murder you with computers” anxiety. Even those familiar with the headline may not have dug into the story too much on account of how silly it sounds, but it’s absolutely well worth checking out if only for the bit about “assassins” and “dangerous sociopaths.”

Has blasting apart your computer “like a large hand grenade” ever been so much fun? Would it only be a little bit terrifying if the hand grenade was incredibly small? How many decently-sized grenades does it take to make your computer explode like a bomb, anyway? Is the bomb also incredibly large? What kind of power are we talking here, because it would frankly be anti-climatic if it turns out to be a hoax.

Maybe the real grenades were the bombs we made along the way

However you stack it up, the antics of highly combustible cyber assassins are often overplayed for dramatic effect. At this point I’d like to ask, “Who remembers the terrible Y2k trend of exploding computers?” but as you’re aware, that didn’t actually end up happening. Lots of hard-working people spent an incredible amount of time ensuring the Millennium bug didn’t cause Millennium-bug related problems, but I don’t think they were thinking of dramatic explosions when they were doing so.

Still, there’s always been a way to affect hardware in (significantly less spectacular) ways, though most of them seem to be a combination of user error or tinkering with hardware hacks. Even the article above mentions someone claiming to make one of these start smoking by writing programs which toggled the cassette relay switch rapidly. I, myself, once woke up to a PC on fire (and I do mean on fire) after something broke overnight and I was met with the smell of metal burning, plastic melting, and an immediate concern related to not having the house burn down around me.

Evil cyber assassins making you explode, though?

Not that common, sorry. However, there has been the occasional bad event down the years where hardware was specifically targeted in frankly terrifying ways. 

Breaking hardware for fun, profit, and confusion

Before we set down some of the most common techniques hardware can be impacted in ways they probably shouldn’t be, we’ll set the bar early and highlight what’s likely the biggest, baddest example of hardware tampering. Stuxnet, a worm targeting SCADA systems, caused large amounts of damage at a nuclear facility in Iran between 2009/10. It did this by speeding up, slowing down, and then speeding up centrifuges till they were unable to cope and broke. Up to 1,000 centrifuges were taken down as a result of the attack [PDF]. This is an assault which clearly took an incredible amount of planning and prep-work to pull off, and you’ll see the phrase “Nation state attack” an awful lot if you go digging into it.

This is, without a doubt, the benchmark for dragging digital attacks into real-world impact. A close runner-up would be 2017s Wannacry attack which impacted the NHS [PDF]. The key difference is that the plant in Natanz was deliberately targeted, and the infection had specific instructions for a specific task related to the centrifuges. The NHS was “simply” caught in the fallout, and not targeted specifically.

Attacks on people at home, or smaller organisations, tend to be on a much smaller scale. The idea isn’t really to break the hardware beyond repair to make some sort of statement; the device is useful because they can keep on using it. Even so, the impact can range from “mild inconvenience” to “potentially life threatening”. 

What’s mining is mine

You could end up with a higher electricity bill than normal should you find some Bitcoin miners hiding under the hood. This might keep you warm on a chilly winter evening, but it’s not particularly advisable for financial outlay or individual PC parts. The problem with your standard Bitcoin miner placed on a system without permission is the resources they gobble up for computations. They love those big, juicy graphics cards for maximum money-making.

Having said that, your child’s middle-range gaming laptop is also a perfectly acceptable target for them. If the cooling fans are going haywire even when no game is running, it might be time to start running some scans. Overheating can be mitigated on desktops unless they’re clogged up with a lot of dust or faulty parts, but the margin for error is a lot smaller with a laptop. All that heat built up in one siginificantly smaller space over time isn’t great, and while toasting the machine wouldn’t be part of the Bitcoin miner’s gameplan, it’s one side-effect to be wary of.

On the flipside, modern systems are actually pretty good at combating heat…especially if you’re even a little bit into gaming. The reason you don’t see stories in the news about evil hackers melting computers is that a) it is, again, ultimately pointless b) it would be pretty difficult to pull off. Hardware comes with all sorts of failsafes, temperature sensors, shutdown routines, power spike protection, and much more. It would mean significant amounts of time and effort, in the vague hope you end up with something a little more impressive than “The PC shut down to prevent damage and it’s fine”.

BIOs / firmware hacks

Could you bludgeon your way into the very innards of the PC, and force it to do all sorts of terrible things? Perhaps. As with a lot of these scenarios, it typically relies on multiple steps and one specific target in mind. Malicious firmware is a possibility, but you’ll need to set the risk besides the likelihood of this happening. Once more, we see the inherent drawback in “make thing go boom”, or even just bricking the machine forever so it’s unusable. Having someone go to these lengths to attack your PC in this way is probably outside your threat model.

Not impossible, but unlikely. Somebody doing the above wants your data, not your laptop on fire. As a result, you absolutely should be cautious when in a place that isn’t your home.

IoT compromise

The world is filled with cheap, poorly secured bits of technology filling up our homes. Security is an afterthought, and even where it isn’t, bad things can still happen. At the absolute opposite end of pretend hackers turning your computer into a bomb, are the people whose sole intention is to compromise devices and live on them for as long as possible. Information, and control, are the two key currencies for domestic abusers implanting hacks into hardware.

Awfully bad, but awfully rare

These are all awful things, in various steep degrees of severity. They tamper with systems and processes in ways which can directly impact the physical operation of a device, or do it in a manner which leaves the object intact but causes trouble in the real world in other, less incendiary ways.

In terms of making things blow up, bomb style, we’re still at a bit of a loss.

All the same: there is a genuine threat aspect to all this, as we’re about to find out.

Strap yourself in and command the DeLorean as we jump from a Register article back in July 2000, to another one along similar lines at the tail end of July, 2020. Despite the warnings, it’s now 20 years on where we’re finally at the point where something a bit like your PC could go kaboom.

The entity known as time comes crashing through the window, reminding me of my melted and very much ablaze PC from about fourteen years ago. Your devices can and do catch fire for a variety of reasons, and they don’t have to be related to hacking.

In the case of a 3D printer enthusiast who found their device bellowing smoke, the likely culprit was a loose heating element and a bit of bad luck to set everything ablaze. Note that the post-incident assessment includes a rework of the physical space around the device. Everything from storage to safety equipment is now considered, to combat (as they put it), the placement of a heavy-duty bit of kit inside a “burn-my-house-down box”.

This is similar to ensuring the space around a VR gaming setup is also secured, in terms of mats on the floor so you know when you’ve wandered out of the safety zone, wires suspended by the ceiling, no sharp / dangerous items nearby and so on. Sadly, people don’t consider the ways in which physical danger presents itself via digital devices.

Keep all of this in mind, when checking out what comes next.

What comes next, is a 3D printer modified with the intention of seeing if it’s possible to “weaponize this 3D printer into a firebomb”.

Weaponizing a 3D printer into a firebomb?

Researchers at Coalfire toiled hard at creating a hand-crafted method to alter the way a specific 3D printer operates and have it hit increasingly dangerous temperatures. In their final bout of testing, the smoke and fumes were so bad in an outdoor location that they couldn’t be closer than 6ft from the smouldering device.

This is, of course, an incredibly bad situation to be in. However, there are some big caveats attached to this one in terms of threat. All 3D printers are a potential fire risk, because they naturally enough involve activities requiring high temperatures. If you leave them alone…and you really shouldn’t…you could end up with the aforementioned burn-my-house-down box. There are also emissions to consider.

In my former life as an artist, I did a lot of work around the old-style MDF which contained all manner of bad things if you cut into it and precautions had to be taken. Similarly, you have to pay attention to what may be wafting out of your printer.

I’ve dabbled in 3D printing a little bit, and the technology encourages me to treat it with a healthy bit of respect on account of how deadly it could be by default, with no tampering required, simply via me getting something wrong.

A good approach generally, I find.

Of worst case scenarios

We don’t know for sure how bad the smoking printer would’ve ended up, given the switch-off when the fumes became too much. A total meltdown seems likely, but a “bomb” as such probably won’t be the case.

This also isn’t something you can casually throw together at the drop of a hat. It’s not one short blog post showing how easy it is; it’s 3 posts of trying an awful lot of things out. Rooting the printer and cracking passwords, digging into board architecture, installing NSA tools to explore functions. Much more.

Creating extra space to house the new code, adjusting the max temperature variable then having to figure out how to bypass the error protection closing down any overenthusiastic temperature increases.

Much, much more.

Note also that to force the device to overheat beyond the safe “cut out” point, they had to replace the power supply with something bigger to achieve the required cookout levels.

It’s an awful lot of work to set your printer on fire. Of course, one worry might be a situation where the modified code is somehow pushed to device owners after some sort of compromise. You could also perhaps send people the rogue code directly as a supposed “update” and let them do the hard work.

One way around this is signed code from the vendor, though there’s usually resistance to that from some folks in maker circles because of issues related to planned obsolescence. Additionally, some prefer to download updates directly from the manufacturer’s website and aren’t keen on auto-updates for their printing tools.

Even so: regardless of the issues surrounding who wants which type of update, or if signed code would fix things or bring unforeseen hassles for the end-user, somebody compromising you remotely with this in some way would still need you to have switched out for a bigger power supply for the big boom.

That’s not very likely.

Hackers: they’ll turn your printer into a BOMB!

For the time being, your printer is (probably) not going to fulfil the prophesied digital cyber-grenade of lore. You’ve got more than enough to be getting on with where basic precautions are concerned, never mind worrying about someone blowing up your house with a toaster or USB headphones.

Treat your 3D printer with respect, follow the safety guidelines for your device, and never, ever leave it running and unattended. You don’t want to end up on the front page of the Weekly World News in 2040.


Christopher Boyd

Former Director of Research at FaceTime Security Labs. He has a very particular set of skills. Skills that make him a nightmare for threats like you.