SIM cloning

SIM cloning consists of duplicating the GSM SIM card, which allows calls or other services to use the identification of the cloned SIM and to be charged to that account.

In the early 1990s, due to poor security, cloning was more common than it is today. Cloning has now been rendered more challenging technically (since physical access to the SIM card is now required, contrary to simply being within radio reach).

SIM cloning is now more difficult to perform, because merely duplicating the contents of the SIM does not enable a duplicate SIM to operate, since the SIM itself performs security operations on the data contained inside to avoid such copying. In order to function, the cloned SIM needs to perform security operations on the data contained, just like the 'original' one.

SIM cloning is a great concern to security/police services since it renders GSM location-based service (LBS) unreliable when more than one handset uses the same SIM.

In the movie "The Bourne Supremacy", the main character clones a SIM card to enable him to listen in to calls to a U.S. official from the CIA. It is widely held that actually cloning a SIM could not be accomplished as quickly as it was in the film.

A realistic time for extracting the Ki from a SIM card is approximately 4-8 hours. There is 40% probability of damaging the card in the process. Additionally, the attacker must have pre-knowledge of the SIM card's PIN (CHV1).Fact|date=September 2007

Cracking Ki by overhearing radio GSM traffic is difficult but not impossible (although illegal in the United States). In many countries GSM traffic is not encrypted thus with proper equipment (a computer based radio scanner (eg. USRP) and the proper software), a hacker could overhear GSM traffic and clone SIMs.

The security has been improved with the newer generation of SIM cards to be used with 3GSM networks, known as USIMs. The new specification implements a new publicly announced algorithm (the KASUMI algorithm).

SIM cloning is also sometimes used to unlock phones from foreign providers for use on your home network; by using your Ki and switching between your IMSI and the IMSI that the phone expects the phone can be fooled into thinking that it has the SIM from its native provider (this is commonly done for Japanese phones as well as the iPhone before its software unlock was released).