A cellphone (also called a mobile phone) virus is the equivalent to a computer virus, only it infects consumer cellphones and spreads by way of MMS attachments, Bluetooth transfers, and Internet downloads. The most common type of cellphone virus is one that travels from computers to cellphones by way of infected files that are downloaded from the Internet. However cellphone-to-cellphone viruses, while less common, do exist.
The first known cellphone virus was called Cabir and was detected in June 2004 by Kaspersky Labs. The Cabir worm was coded to infect Symbian OS cellphones. Cabir was designed to scan for all accessible phones using Bluetooth technology, and send a copy of itself to the first one found. Setting your phone into a non-discoverable (hidden) Bluetooth mode will protect your phone from the Cabir worm. But, once the phone is infected it will try to infect other systems even if you try to disable Bluetooth from system settings. In 2005 Cabir's source code became widely available on the Internet.