Fortinet this week announced the discovery of a new worm targeting Symbian OS phones on mobile networks.

Dubbed Beselo.A, the worm runs on Symbian S60 devices including Nokia 6600, 6630, 6680, 7610, N70 and N72 phones.

"After an installation phase, the worm engages in a propagation routine: phone numbers located in the contact list of the devices are harvested, and targeted by viral MMS carrying a SIS-packed (Symbian Installation Source) version of the worm," according to a company statement. "However, the SIS file does not bear a .sis file extension - rather, it is disguised as a multimedia file with an evocative name: Beauty.jpg, Sex.mp3 or Love.rm."

"In addition to harvesting the numbers stored in the phone address book as mentioned above, the Beselo worm sends itself to generated numbers as well," the security firm adds. "Interestingly, all those numbers are located in China and belong to the same mobile phone operator... The whys and hows of such a routine are still under investigation."

According to F-Secure, the worm also has a "big brother," Beselo.B. "If you have a Symbian S60 phone, and you receive a media file, answer 'no' to any installation prompt that appears when trying to open the file," F-Secure advises. "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."

More here from VNUnet ... more here from CNET News ... more here from PC World ... more here from mobilised ... more here from iTnews ... more here from The Register ... and Fortinet's press release is here.