Cracking GSM

Abstract

Next year – 2012 – will be the 30th anniversary of the birth of the GSM standard. Back in 1982, the European Conference of Postal and Telecommunications Administrations (CEPT) created the Groupe Special Mobile (GSM) standard to allow mobiles to be used across Europe. In 1989, the development process was transferred to ETSI, the European Telecommunications Standards Institute, and phase I of the GSM specifications was published in a year later. The GSM standard is about to reach its 30th anniversary. But although it uses encryption to protect the integrity of the data transmissions – voice calls or data – the technology has been shown to have some serious vulnerabilities. Many of these stem from the fact that the mobile device must authenticate itself to the network over the air. This is achieved through a combination of the International Mobile Subscriber Identity (IMSI) – the unique electronic serial number of the SIM card inserted into the phone – and the International Mobile Equipment Identity (IMEI), which is a unique serial number of the mobile. But recent research has shown how these can be intercepted and spoofed. Steve Gold investigates GSM's weak spots.