Millions of Sim cards are 'vulnerable to hack attack'

A flaw with mobile phones' Sim card technology is putting millions of people at risk of being spied on and robbed, according to a leading security expert.

Karsten Nohl has said he has found a way to discover some Sims' digital keys by sending them a special text message.

He warned criminals could potentially use the technique to listen in on calls or steal cash.

Industry organisation - the GSMA - said it was looking into the findings.

"Karsten's early disclosure to the GSMA has given us an opportunity for preliminary analysis," said a spokeswoman for the association, which represents global network operators,

"We have been able to consider the implications and provide guidance to those network operators and Sim vendors that may be impacted.

"It would appear that a minority of Sims produced against older standards could be vulnerable."

Mr Nohl has posted preliminary details of the vulnerability on the website of his company, Berlin-based Security Research Labs.

Sim (subscriber identity module) cards effectively act as a security token, authenticating a user's identity with their network operator.

They also store a limited amount of data such as text messages, contacts' telephone numbers and details used for some applications - including a number of payment and banking services.

Mr Nohl said he had found a way to discover the authentication code by sending a device a text message masquerading as a communication from the user's mobile operator.

The message contained a bogus digital signature for the network.

:story: BBC News