Virus warning: Mobile bug launches attack

Mobile phone viruses, largely considered a paper tiger in the digital security world, became a bit more dangerous this week with the release of a two-pronged program.

Antivirus company F-Secure said on Monday that writers have released a virus, known as Lasco.A, that spreads both through wireless connections and by attaching itself to files,. Until now, malicious mobile phone programs have spread using one mechanism or the other.

"We have received a new Symbian malware that combines two spreading tactics, which is common in PC malware but previously unheard of in mobile systems," F-Secure said in a posting on its website.

The Lasco.A virus will attach itself to any application file on a phone that uses the Symbian operating system, F-Secure said. It is activated when mobile phone owners click on the file and install it on their handsets.

"Thus any [application] file in the device that gets copied to another phone, as frequently happens as people swap software, will also contain a copy of Lasco.A," F-Secure said.

The program also acts like a computer worm, attempting to copy itself directly to any phone within range using Bluetooth wireless technology, F-Secure said. That capability is similar to several recent worms -- variants of the Cabir worm -- that have managed to spread to a limited amount of phones in the wild.

Such programs have not been very successful, however. Only recent mobile phone operating systems are programmable to the extent that viruses can effectively spread. Moreover, the large number of proprietary operating systems used in mobile phones make the development of broad threats much more difficult.

As the new virus can only spread on mobile phones that have Bluetooth in discoverable mode, the best way to protect handset systems is to set it to hidden Bluetooth mode, F-Secure has advised.

Robert Lemos writes for CNET News.com.