Most people reading this won't know who Bunny Huang is, but he does a regular on his blog called "Name that ware". Basically, a bare PCB is photographed and put up, and people have to guess what device it came from. This is often a lot easier than it sounds: key components and design features often narrow down the range extremely quickly.
Somewhat close to the bone, this month's "Name that ware" was the PCB used in the Laserjet cartridge bomb found a few days ago at our East Midlands Airport. As per usual, the contributors narrowed down the hardware very quickly to an extremely common (and cheap) Nokia model.
Bunnie's follow-up thoughts on the design are extremely interesting. It's always insightful to get thoughts from someone expert but not State-sponsored, and there are a number of things Bunnie says which are quite inconsistent with what has been said in the media:
- assuming it was meant to be detonated remotely, it wasn't well-designed;
- in any event, it wasn't well put together.
Clearly, it has been put together to some kind of recipe, though. PETN, the explosive used, is slightly more stable than simpler compounds, and can be manufactured from simple components. It's World War 1-era, so quite basic, but effective - and doesn't need an awful lot of expertise to put together (the news says they're currently holding a medical student: that would fit; PETN is also used as a heart medicine...)
In addition to that, they made sure to pick the right type of handset: the Nokia model is quad-band, so you can send it pretty much anywhere in the world and with the right SIM it will work, but it's so simple that anyone can modify the PCB without too much hassle.
The picture of the PCB shows it was mounted onto the printer, which from the pictures on the news is an HP Laserjet P2055. Again cheap and common, but someone would have needed to do a bit of research to make sure that there was room for the PCB in a location which wasn't suspicious - this one was mounted just below the main controller board, and on an X-Ray machine would have probably looked quite normal.
For it to work, someone would have also needed to research the cartridges to make sure that they had enough capacity for the explosives (cheap printers often can't take much toner), and that there was some sensible way of getting the detonation wires into the body of it. So again, someone figured out how to get this all done, but the person who actually put this together probably didn't need to know that much: anyone with basic electronics skills who knows the business end of a screwdriver and soldering iron could have created this thing.
So the whole "this was put together by professionals" schtick I don't really buy. It's not unbelievable that someone posted the guide to making these things online at some point for anyone to put together. Obviously some thought was put into the making of this, but when you think through the logic:
- We need space for explosive, packed into some area that would usually have some kind of inert substance;
- We need electronics to hide our trigger mechanism in;
- We need something of a decent size so the extra weight isn't noticed.
... things start getting pretty easy, and a Laserjet is a decent choice. But if the idea was to blow a plane up mid-flight, it's not a great design: as well as the problem with the aerial on the PCB, it was mounted against a large piece of metal which could also cause problems with signal reception. The only chance would be as the aircraft comes in to land, which would require some spectacular timing on the terrorist's part (not to mention danger, as they would need to be pretty close to the airport they're trying to cause the accident at, unless they just war-dialled the device continually).
This kind of home-brew kit doesn't make me think this is some kind of well-organised and orchestrated effort. If you set this same problem to a couple of University electronics/chemistry students, they'd come up with something similar but (I would bet) much better designed, and it's a level of engineering which anyone with sufficient motivation could teach themselves this stuff.
Of course, that's not to say it's not scary: of course it's incredibly scary that people can get PETN onto aircraft, and the fact that they've come up with a half-practical design is also worrying.