wikileaks in a jam

Vexation about the publication on Wikileaks of some US Army documents with details of the counter-IED radio jammers. Well, you can see why they’re concerned; but I very much doubt this is particularly important.

Recap: the New-Old Iraqi Army was in the habit of using command-detonated IEDs to blow up Coalition and Iraqi government road convoys. To begin with, the command element was often either a GSM device or else some sort of el cheapo radio device like a garage-door opener, RF thermostat, bits and pieces from an industrial process-control rig or the like. After much spending and much fuss, the US Department of Defense deployed “secret” but much hyped jammers on the lead vehicles in the convoys.

Now, there was almost certainly no reason to spend anywhere as much as they did. This is directly linked to the non-fuss about Wikileaks. The devices we have just mentioned have an internationally-standardised frequency band to chatter away in – the so-called Industrial Scientific Medical band, which is unlicensed spectrum – anyone can use it for anything, so long as they don’t use too much power. Among other things, all the world’s WLAN access points work in the ISM 2.4GHz band, as do wireless hi-fi speakers, baby monitors, cheap CCTV cams, etc, etc. So right back in 2003, it was blindingly obvious which frequencies were involved and what an upper bound on the power output would be. Which made the problem of jamming it pretty simple – just hammer away in the ISM with noise at a significantly higher Tx wattage.

Radio waves are electromagnetic radiation, and therefore their intensity changes with the inverse square of the distance from the source. So you could trivially calculate how much power you need to trigger the device a given distance away from the target. All you need is something that will radiate in the ISM band on command, like…a WLAN card, which now costs about five quid (or, perhaps, a door opener with a better antenna…). I have to say, I suspect that Donald Rumsfeld got played terribly over this. And, of course, nothing radio-frequency stays secret once you start transmitting; everyone can hear you.

There are cleverer things you can do; regarding the GSM ones, you could carry a malicious base station around with you, and therefore blackhole all traffic to and from phones in range. Or you could tap the phones and find out whodunnit (we know the other side do it to us). If I was really serious about this, I’d use one of these, which can be programmed to emulate pretty much anything radio.

So, like so much government secrecy, this is much more to do with security from embarrassment (we spent $billions on technology that would have been cutting edge in 1940!) than security from anything else.




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