SIM or subscriber identity module is essential in mobile communication, SIM is a microchip or an electronic circuit that stores IMSI and other authentication and identification code. The foremost objective of SIM is to give the identification of its owner in the mobile communication network, it also carries the network signals that can hacked to control a mobile phone. How to hack into a SIM card is not the primary objective of this article, however we will study the structure of a SIM and exploitation process.
At DEFCON 21 talk, Karl Koscher and Eric Butler have presented their research and understanding regarding the said topic. Following is the abstract of what's discussed there: