Here’s something interesting. You may remember this story from back in November about the CIA spy network in Lebanon that met at a Pizza Hut they codenamed PIZZA, and which was rolled up by a joint Hezbollah-Lebanese military intelligence investigation. The key detail is as follows:
U.S. officials also denied the source’s allegation that the former CIA station chief dismissed an email warning that some of his Lebanese agents could be identified because they used cellphones to call only their CIA handlers and no one else.
Lebanon’s security service was able to isolate the CIA informants by analyzing cellphone company records that showed the numbers called, duration of each call and location of the phone at the time of the call, the source said.
Using billing and cell tower records for hundreds of thousands of phone numbers, software can isolate cellphones used near an embassy, or used only once, or only on quick calls. The process quickly narrows down a small group of phones that a security service can monitor.
If the top paragraph is true, it would have been catastrophically ill-advised. Even somebody special, like a CIA agent under diplomatic cover, has a relatively large number of weak ties to normal people. This is the reverse of the small-world principle, and is a consequence of the fact that the great majority of people are real human beings rather than important persons. As a result, things like STELLAR WIND, the illegal Bush-era effort to analyse the whole pile of call-detail records at AT&T and Verizon in the hope that this would find terrorists, face a sort of Bayesian doom. We’ve gone over this over and over again.
However, phone numbers that only talk to special people are obviously suspicious. Most numbers with a neighbourhood length of 1 will be things like machine-to-machine SIMs in vending machines and cash points, but once you’d filtered those out, the remaining pool of possibles would be quite small. It is intuitive to think of avoiding surveillance, or keeping a low profile, but what is required is actually camouflage rather than concealment.
There are more direct methods – which is where electronic warfare and shopping mall management intersect.
Path Intelligence, a Portsmouth-based startup, will install a network of IMSI-catchers, devices which act as a mobile base station in order to identify mobile phones nearby, in your shopping centre so as to collect really detailed footfall information.
Similarly, you could plant such a device near that Pizza Hut to capture which phones passed by and when, and which ones usually coincided. Alternatively, you could use it in a targeted mode to confirm the presence or absence of a known device. Which makes me wonder about the famous Hezbollah telecoms network, and whether it was intended at least in part to be an electronic-intelligence network – as after all, nothing would be a better cover for a huge network of fake mobile base stations than a network of real ones.
Meanwhile, this year’s CCC (like last year’s) was just stuffed with GSM exploits. It really is beginning to look a lot like “time we retired that network”.