July 20th, 2006 at 16:59 UTC by Ross Anderson
Yesterday my wife received through the post a pre-approved unsolicited gold mastercard with a credit limit of over a thousand pounds. The issuer was Debenhams and the rationale was that she has a store card anyway – if she doesn’t want to use the credit card she is invited to cut the credit card in half and throw it away. (Although US banks do this all the time and UK banks aren’t supposed to, I’ll leave to the lawyers whether their marketing tactics test the limits of banking regulation.)
My point is this: the average customer has no idea how to ‘cut up’ a card now that it’s got a chip in it. Bisecting the plastic using scissors leaves the chip functional, so someone who fishes it out of the trash might use a yescard to clone it, even if they don’t know the PIN. (Of course the PIN mailer might be in the same bin.)
Here at the Lab we do have access to the means to destroy chips (HNO3, HF) but you really don’t want that stuff at home. Putting 240V through it will stop it working – but as this melts the bonding wires, an able attacker might depackage and rebond the chip.
My own suggestion would be to bisect the whole chip package using a pair of tin snips. If you don’t have those in your toolbox a hacksaw should do. This isn’t foolproof as there exist labs that can retrieve data from chip fragments, but it’s probably good enough to keep out the hackers.
It does seem a bit off, though, that card issuers now put people to the trouble of devising a means of the secure disposal of electronic waste, when consumers mostly have neither the knowledge nor the tools to do so properly