Symbian S60 Malware out in the wild.

F-Secure has today been reporting that two variants of a new mobile phone worm have been discovered in the wild.

The SymbOS/Beselo family of worms, comprising of Beselo.A and Beselo.B, have been infecting S60 2nd Edition phones, and is spreading via MMS and Bluetooth when users are tricked into running an incoming Symbian application installer (.sis) file.

The malware never advertises itself as such, preferring to use common media extensions and vaguely enticing filenames, such as beauty.jpg, sex.mp3, and love.rm.

F-Secure has noted that both worms have been able to escape operator and antivirus company attention for some time by employing this simple disguise.

F-Secure has advised users of S60 phones to reject any installation prompt that appears when trying to open a media file such as jpg, mp3, or rm.

"There is no reason for any image file to ask installation questions on the Symbian platform, so any image or sound file that does something else than play immediately is without question something else than it claims to be," the company writes on its blog.

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