A US TV station has demonstrated how easy it is to lift credit card details from proximity-payment cards, though in the process showing just how pointless the activity is.
The video does a nice job of demonstrating just how close you have to be to read a card, which are induction-powered so have very limited range; you needn't worry about the chap walking behind you, but tube travellers might be concerned about the one pressed against them... But with typical hyperbole, the channel fails to point out the limited risk such reading presents.
The attacker is shown reading the card number and expiry date, which the presenter interprets to mean that 140 million credit card users are at risk, and goes on to ask why the credit card companies aren't doing anything about it.
The reason, of course, is that the risk isn't significant, at least not yet. Remote readers can't pick up the CCV code, which is on the back of the card (the three digits on the signature strip), or the card holder's address – both of which will be required for any online transaction.
So could sniffing the card allow the criminal to create a clone of the card sniffed, then use it at a contactless pay point? Probably, though it would be difficult and not risk-free for the criminal – proximity payments are only used for small-value transactions, and will ask for a PIN at random (which the criminal won't have) as well as leaving a detailed paper trail. Such a card would only work for offline payments, where no challenge-response mechanism is used, and while such things are permitted by the standards, their use could easily be reduced if it became a problem.
So if you notice the stranger behind you shuffling too close, they're more likely trying to cop a feel than to wirelessly pick your pocket: there are a lot more perverts than technically-proficient thieves prepared to go so far for the price of a cup of coffee. ®