Getting a Personal Unlock Code for Your O2 Cell Phone

O2 is a UK cell phone network. The company gives you the option of setting up a PIN on your phone. The idea is that if someone steals your phone, they can’t make calls. If they type the PIN incorrectly three times, the phone is blocked. To deal with the problems of phone owners mistyping their PIN — or forgetting it — they can contact O2 and get a Personal Unlock Code (PUK). Presumably, the operator goes through some authentication steps to ensure that the person calling is actually the legitimate owner of the phone.

So far, so good.

But O2 has decided to automate the PUK process. Now anyone on the Internet can visit this website, type in a valid mobile telephone number, and get a valid PUK to reset the PIN — without any authentication whatsoever.

Oops.

EDITED TO ADD (7/4): A representitive from O2 sent me the following:

“Yes, it does seem there is a security risk by O2 supplying such a service, but in fact we believe this risk is very small. The risk is when a customer’s phone is lost or stolen. There are two scenarios in that event:

“Scenario 1 – The phone is powered off. A PIN number would be required at next power on. Although the PUK code will indeed allow you to reset the PIN, you need to know the telephone number of the SIM in order to get it – there is no way to determine the telephone number from the SIM or handset itself. Should the telephone number be known the risk is then same as scenario 2.

“Scenario 2 – The phone remains powered on: Here, the thief can use the phone in any case without having to acquire PUK.

“In both scenarios we have taken the view that the principle security measure is for the customer to report the loss/theft as quickly as possible, so that we can remotely disable both the SIM and also the handset (so that it cannot be used with any other SIM).”

Posted on July 3, 2006 at 2:26 PM

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