The leak reports that are published by The Intercept, reveal that hacking into the system of Gemalto, NSA and GCHQ had stole millions of the encryption keys that are used to protect the privacy of cell phone communications. These encryption keys were used to decrypt voice and data communications without alerting users, networks or governments.
NSA and GCHQ formed a special team Mobile Handset Exploitation Team (MHET) in April 2010, which specially targets the users cell phones and exploits the vulnerabilities on phones to gain the data.
The documents also reveal that some of the companies involved in SIM production didn't take strong measures to protect users’ personal and sensitive data. According to report, "many" SIM card manufacturers sent the encryption keys to wireless network providers with weak encryption methods that can be broken or no encryption at all.
In a statement, the Gemalto says: “We take this publication very seriously and will devote all resources necessary to fully investigate and understand the scope of such sophisticated techniques.”