The cyber researchers said that SIM cards using old encryption technology i.e. Data Encryption System(DES), make the devices vulnerable to attacks. The German firm Security Research Labs discovered the mobile bug in 500 million mobile phones as the DES encryption is used in one out of eight devices around the world.

The researchers said that the bug allows hackers to gain control of and also clone certain mobile SIM cards. The hacking only works on SIMs that uses old encryption technology.  Once a hacker copies a SIM, it can be used to make calls and send text messages impersonating the owner of the phone.