Summary

Bootton.F is a SIS file that installs a small software component that resets the device. This component will be executed automatically after installation and at system start up. That causes the reboot to fail and leaves the phone in an unusable state.

Disinfection

CAUTION! This method will remove all data on the device including the calendar and phone numbers:

1. Power off the phone
2. Hold following three buttons down "answer call" + "*" + "3"
3. Keep holding the buttons and power on the phone
4. Depending on the model, you either get text "formatting" or start-up dialog that asks for initial phone settings
5. Your phone is now formatted and can be used again

Additional Details

In its structure, Bootton.F is quite similar to SymbOS/Bootton.E with the exception that instead of needing user action to reboot the phone it does so automatically after installation and at the phone's start up.

Detection

F-Secure Mobile Anti-Virus for Symbian detects this malware starting from the update build number 44.

Write-up: Mika Tolvanen, May 10, 2006

Technical Details: Mika Tolvanen, May 10, 2006

F-Secure Corporation