On 17th November we were able to confirm that 8 customers had been unlawfully upgraded to a new device by fraudsters who intended to intercept and sell on those devices.
I can now confirm that the people carrying out this activity were also able to obtain some customer information. In total, information from 133,827 customer accounts was obtained but no bank details, passwords, pin numbers, payment information or credit/debit card information are stored on the upgrade system in question.
We believe the primary purpose of this was not to steal customer information but was criminal activity to acquire new handsets fraudulently.
We are contacting all of these customers today to individually confirm what information has been accessed and directly answer any questions they have.
As an additional precaution we have put in place increased security for all these customer accounts.
There's some good news here. No passwords were exposed, and no financial information.
Furthermore, although customer contact information could be abused by scammers in an attempt to extract further details (such as banking information) it doesn't appear that this was the motivation for the attack. Instead, by all accounts, the belief is that criminals were ordering new phone upgrades on behalf of individuals, and then physically intercepting the devices' delivery in order to sell them on to others.
Three says it is working closely with law enforcement agencies, and appears to be keen to communicate with affected customers. Good for them!
More information can be found in Three's FAQ.