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Mosquito software bites smart phones

A possible Trojan horse hidden in an illegal cell-phone game hits smart phones using the Symbian operating system.

A new possible Trojan horse making the rounds forces some cell phones based on the Symbian operating system to generate pricey text messages.

The software resides in an illegal version of the cell phone game "Mosquito" that is now available at no cost on the Internet and peer-to-peer networks, according to a statement from Symbian, the company that licenses the operating system of the same name.

Symbian, which has identified the problem as a Trojan horse, said the software did not seem to have been created with malicious intent. Rather, the feature was incorporated in early versions of the game by the legitimate manufacturer, Ojom, as an experimental licensing and copy protection mechanism. The illegal copies are based on an early version of the game and still include the message feature, Symbian said.

But others, including security company F-Secure, have called into question whether the software is a Trojan horse at all. Some reports describe it as an antipiracy feature that forces phones that illegally download the Mosquito software to make a costly call.

Once installed, the game may cause phones to send text messages to premium rate numbers in the United Kingdom, Germany, the Netherlands and Switzerland without the user's approval or knowledge, Symbian said. Deleting the game rids users of the problem, the company said.

"The Mosquito Trojan is a clear indication that users need to be aware of the risks of downloading and installing illegal or pirated software," Symbian said. "Symbian believes that mobile security is the responsibility of the entire industry. It requires cooperation and trust."

The company did not offer an estimate of the number of phones affected nor when the virus began making the rounds.

The episode underscores how virus writers are now focusing on smart phones, which are cell phones that are always connected to the Internet and that have PDA-like processing power for much more complex tasks than a typical handset. The two major makers of smart-phone operating systems are Symbian and Microsoft.

The buzz about the Mosquito Trojan comes about a month after antivirus companies began deciphering the workings of the first worm to target smart phones. That worm program, dubbed Cabir by Russian antivirus company Kaspersky, apparently uses the Bluetooth short-range wireless feature of Symbian-based smart phones to transfer itself as a package file to other Symbian phones. While able to replicate the spread of the virus in research settings, antivirus companies have not found any evidence that the program is infecting smart phones outside some limited test cases.

In mid-July, a virus that infects Windows CE was developed--the first such bug discovered for the handheld operating system, according to one firm. Romania-based BitDefender said it has discovered a "proof of concept" virus for Microsoft's operating system for smart phones and other handhelds. The malicious code's author, who uses the pseudonym Ratter, is part of the 29A VX group that created a virus for the Symbian operating system.