Trojan trips up some smart phones

A Trojan program called Skulls has appeared, disabling many of the functions of Internet-enabled cell phones that use the operating system from the Symbian Ltd. consortium.

The Finnish company F-Secure Corp. said the software, masquerading as Extended Theme Manager, was first identified Nov. 19. F-Secure is reporting isolated cases of it being downloaded from a Symbian shareware site.

Once installed, application icons are replaced with skull-and-bones icons that no longer point to the applications. This reduces the device to a mere telephone on which you can make and answer calls.

The file is named Extended theme.sis and claims to be a theme manager for the Nokia 7610 smart phone, written by Tee-222. It does not contain any actual malicious code, according to F-Secure.

"It is just a Symbian installation file that installs critical system ROM binaries into the C: drive with the same names and locations as in the ROM drive," F-Secure reported.

This replaces the ROM drive files, and an Application Info and Icon file then replaces the icons with phonies that point nowhere.

Uninstalling the Trojan appears to require a third-party file manager on the infected phone. A description of the program and directions for disinfecting are available online from F-Secure [http://www.f-secure.com/v-descs/skulls.shtml].