Mobiles can be infected by worms that spread themselves via the mobile phone network.

In 2004, the first mobile phone worm was written. The Cabir-A worm affects phones that use the Symbian operating system, and is transmitted as a telephone game file (an SIS file). If you launch the file, a message appears on the screen, and the worm is run each time you turn the phone on thereafter. Cabir-A searches for other mobile phones nearby using Bluetooth technology, and sends itself to the first it finds.

There are also conventional viruses that send messages to mobile phones. For example, Timo A uses computer modems to send text (SMS) messages to selected mobile numbers, but in cases like these the virus can’t infect or harm the mobile phone.

Until now, the risks for mobile phones have been few. The reason could be that they use many different operating systems, and that the software and device characteristics change so rapidly.