The Symbian mobile phone operating system is once again under malware attack, this time from the Trojan Doomboot.A. Many users have found their handsets infected after downloading unauthorised mobile phone games containing the malicious code. It is now estimated that around 30 million phones are potentially threatened.

The worm propagates itself by sending messages via MMS and short-range Bluetooth, both of which are fairly standard features in smart phones. "The worm sends a continuous stream of MMS messages, which will drain the battery of most phones in about an hour," Von Troyer said. "When users try to reboot, they can't. Their handsets needs to be reformatted, resulting in complete loss of their data, such as photos, calendar and address book."

"We're suggesting that people use common sense when going to websites and downloading unauthorised Symbian-based mobile phone games," Von Troyer said. "And we're also recommending that they use anti-virus programs to protect their devices from viruses, Trojan horses and worms."