Whack-a-Mole
I assume the Black Hats have been using cellphone SIMs because they're easy, convenient, cheap and reliable. Why bother building a sui generis receiver-transmitter detonator system when you can buy it in a supermarket? With security services and police whacking that particular mole, WiFi is a reasonable thing to try, but it's easy to imagine this arms race regressing to the bad old days of the 1980s, when PIRA were developing their own technology for 'button jobs'—remotely detonated bombs. (ISTR they actually succeeded with one somewhere in mainland Europe.) There are also, of course, plenty of RC plane controllers and similar that could be adapted to the job. So blanketing the RF spectrum in vulnerable regions seems to be the way to go.
But then I think: you can buy the bits for a moderately powerful LED laser, something like the emitter for a desktop engraving system, and knock up a circuit to provide some modulation (simple on-off broadcast of a single byte over the course of half a second, even) and, with sensible choices for collimation, receiver sensitivity and filtering, achieve an effective range of several hundred metres at least. Perhaps several klicks on a clear night. All sorts of possibilities open up if you think about lasers. Your bomb just needs to be in line of sight, or trail a detector/detonator thread to a lens in a location that's LoS. Or just position it near something suitably reflective. And they're unjammable except by optical interruption.
In many types of arms race, one of the competitors tends to keep the initiative, and I suspect here it remains with the Black Hats—very much so if they are technologically savvy.
For a very long time—since at least the time of a bunch of lame brains who conspired with supreme incompetence to blow up planes with purportedly binary explosives—I have thought that the main thing preventing terrorist atrocities is the incompetence of the wannabe terrorists themselves. And it still seems to me that we should be most afraid of a disciplined, intelligent, careful bad guy who has competence in chemistry and electronics. With resources in less than four figures (£$€) I would expect such a person to be able to cause major havoc.
I'm not sure about the counter-terrorism work being done by MI5, FBI, NSA etc: no doubt it is excellent. But whoever has been somehow ensuring that wannabe perpetrators of atrocities are poorly educated, careless and lazy has really been doing sterling work. Long may this state of affairs continue.
Biting the hand that feeds IT
