Lasco.A spreads by searching for all SIS installation files on an infected phone and embedding itself within the files, according to a security notice published by F-Secure. That means that as users trade programs, they'll spread the worm. Lasco.A also tries to infect phones that have Bluetooth connectivity enabled.
Malicious code threats which target mobile phones have been theoretical for years, until recent months. In November and December, several variants of the Skulls cell-phone Trojan and the Cabir Bluetooth worm surfaced. Antivirus companies said they received some reports of infections.
Most antivirus companies that offer protection for mobile phones offer protection against Lasco.A, or will soon. Security experts suggest those with Bluetooth-enabled phones not leave them on in "discoverable" mode.