All About Technologies

So now that you hopefully have at least a basic understanding of how gsm operates, let’s talk about the fun stuff. The first trick I will discuss is an activity that is becoming quite prevalant, SIM cloning. If you have paid attention to any cell phone related tutorials in the past, then you may remember cloning being made popular by certain public figures like Kevin Mitnick in order to place calls on the bill of another subscriber. Well, even with GSM this trick still holds relevant. How could such a flaw exist in a system that is obviously concentrated on preventing such fraudulant use? The flaw is within the COMP128 authentication algorithm used as an instantiation of A3/A8 widely used by gsm providers. Unfortunately for these providers, the COMP128 algorithm is just not strong enough to prevent fraud. We attack the algorithm by using a chosen-challenge attack, which works by forming a number of specially-chosen challenges and querying the SIM card for each one. Then by analyzing the responses from these queries, we are able to determine the value of the secret key that is used for authentication. So how do we perform this attack?

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As I’ve said in past tutorials, in order to hack anything in any sense of the word you have to first understand how it operates. Therefore in this section you will learn the details on GSM to have a better understanding of how it operates. Therefore, you will have a better understanding of how it can be exploited. GSM (Global System for Mobile communication) is fundamentally different from some of it’s older counterparts like AMP in the sense that it operates using digital technology, instead of using the traditional analog technology. GSM being a cellular system is of course divided into cells. These cells correspond to their covering area of one trasmitter, or a small collection of transmitters. The size of these cells depend on the power of their transmitter. GSM, as with other cellular systems, uses low power transmitters so that frequencies can be reused efficiently. The frequency band used by a cellular mobile radio system is distributed over a group of cells, which is repeated in all the covering area of an operator. All the radio channels that are available can then be used in each group of cells that form the covering area of an operator. The frequencies that are used then will be reused several cells away.

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Mig33 is a global mobile community that lets you keep in touch with friends and family through a variety of online services, right on your mobile phone.

With mig33, you can chat and send instant messages and emails, make inexpensive international phone calls, share photos, connect with old friends and even meet new ones. Think of it as an addition to your phone’s existing service. Read the rest of this entry »