A mobile phone virus is a computer virus specifically adapted for the cellular environment and designed to spread from one vulnerable phone to another. Although mobile phone virus hoaxes have been around for years, the so-called Cabir virus is the first verified example. The virus was created by a group from the Czech Republic and Slovakia called 29a, who sent it to a number of security software companies, including Symantec in the United States and Kapersky Lab in Russia. Cabir is considered a "proof of concept" virus, because it proves that a virus can be written for mobile phones, something that was once doubted.
Cabir was developed for mobile phones running the Symbian and Series 60 software, and using Bluetooth. The virus searches within Bluetooth's range (about 30 meters) for mobile phones running in discoverable mode and sends itself, disguised as a security file, to any vulnerable devices. The virus only becomes active if the recipient accepts the file and then installs it. Once installed, the virus displays the word "Caribe" on the device's display. Each time an infected phone is turned on, the virus launches itself and scans the area for other devices to send itself to. The scanning process is likely to drain the phone's batteries. Cabir can be thought of as a hybrid virus/worm: its mode of distribution qualifies it as a network worm, but it requires user interaction like a traditional virus.
Cabir is not considered very dangerous, because it doesn't cause actual damage, and because users can prevent infection by simply refusing to accept suspicious files. However, the virus's code could be altered to create more harmful malware that might, for example, delete any information stored on phones it infects, or send out fake messages purporting to be from the phone's owner.