Trojan:SymbOS/Blankfont is a family of SIS file trojans that install a corrupted Font file.
Disinfection
Disinfection
• Uninstall the SIS file with which Trojan:SymbOS/Blankfont was installed
• To make sure that uninstallation was successful, scan your phone with antivirus before rebooting the phone
F-Secure Mobile Anti-Virus can be downloaded from f-secure.mobi.
Disinfection for cases when the phone has been rebooted
CAUTION! This method will remove all data on the device including calendar and phone numbers
• Power off the phone
• Hold following three buttons down "answer call" + "*" + "3"
• Keep holding the buttons and power on the phone
• Depending on the model, you either get text "formatting" or start-up dialog that asks for initial phone settings
• Your phone is now formatted and can be used again
Additional Details
Trojan:SymbOS/Blankfont copies corrupted font files into the phone's memory and thus prevents the phone from loading the valid font files from ROM.
The corrupted font files installed onto the phone will not cause the device to crash, but if the device is rebooted it will then lose the system font and will be unable to display user interface texts.