Return of the MAC

Anna Chapman and her UN-based Russian government handler allegedly held ten meetings around Manhattan between January and June. They would not make overt contact but would exchange data over an ad hoc Wi-Fi network.

Chapman and the offical made things easy for their watchers, however, by using the same laptops with the same MAC addresses every time. It meant the FBI could tell whenever the pair were in contact simply by following them and using an off-the shelf Wi-Fi network analyser package to match the two MAC addresses.

The pair could have simply used multiple machines, or used any one of an array of utilities that would have allowed them to spoof their MAC addresses. Instead, the FBI's complaint that Chapman was an undeclared agent of a foreign government draws heavily on correlating the two numbers broadcast between her laptop and her handler's.

Chapman knew enough about countering surveillance to buy a "burner" mobile phone and international calling card under a fake name to contact Moscow, apparently after she suspected her new handler (in fact an undercover FBI agent) was not all he seemed last weekend. But that was after she had given him her laptop for repairs.

There are plenty of other options of course for more secure coffee shop wireless data exchanges; post your idea in comments.