Does your ringtone sound a little sickly?
By Lia Timson

It's official. Your mobile phone can now catch a virus. The first mobile viruses have begun to circulate and experts say wider infection is inevitable.

Some, such as Cabir and its variants, look for nearby phones and hand-held PCs, or PDAs, with a "visible" or "discoverable" Bluetooth connection before jumping and prompting users to download it. The worm has been detected on Nokia 3650, 6600 and N-Gage smart phones and drains the batteries.

Another, named Skulls, changes icons on phone screens but is not known to cause any damage.

The first Pocket PC virus, Dust, was detected last July. It also propagates by proximity before seeking permission to infect by asking: "Dear user, am I allowed to spread?" Other threats have been found embedded in pirate copies of computer games for mobile phones.

Security software firm McAfee says a Trojan remained in a pirated copy of Mosquitos after the game manufacturer deleted an SMS-sending function used to monitor piracy. A pirated version, however, kept the function and reprogrammed it to send unauthorised messages to other numbers, clocking up large bills for the user. Other variants used the equivalent of PC-based "porn diallers" to automatically dial-up premium-priced phone numbers in order to generate profit for their providers.

James Turner, a security analyst with the research firm Frost & Sullivan, says that as people become more reliant on their smart phones, writers of malicious code will see them as prize targets. Organised crime gangs might hire experienced mobile hackers to get access to sensitive information, as is the case now with phishing (using hoax emails and websites to gather personal information such as bank account details) and other internet-based attacks.

The only factor holding hackers back is the number of different handset models used around the world. "Getting a virus that will work on a lot of handsets is not easy, but mobile platforms have not been developed with security in mind," says Frost & Sullivan analyst Chia Seller.

There are several anti-virus programs available for Palm, Pocket PC and phones such as Nokia that use the Symbian operating system. The anti-virus software comes from companies such as McAfee, F-Secure and Symantec. McAfee marketing director Allan Bell says they are not the only answer.

"The average user doesn't need to go out there and buy protection. They need to use best practices such as disabling Bluetooth visibility, saying 'no' to unknown downloads and not opening every email attachment they get," he says.

Mr Turner says the virus writers will not give up and consumers must stay vigilant. "Humans will always be the weakest link."