Trojan:SymbOS/Blankfont.C

Classification

Malware

Trojan

SymbOS

Blankfont.C

Summary

Trojan:SymbOS/Blankfont.C is a SIS file trojan that installs corrupted system binaries/font file. The system files dropped by Blankfont.C cause the device to fail on the next reboot. If you have installed Blankfont.C, the most important thing is not to reboot the phone and follow the disinfection instructions in this description.

Removal

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

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

Suspect a file is incorrectly detected (a False Positive)?

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest detection database updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    NOTE If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note You need administrative rights to change the settings.

Find out more

Knowledge Base

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User Guide

See the user guide for your product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical 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 file installed to the phone does not cause device to crash, but if the device is rebooted it will then lose the system font and is unable to display user interface texts.

Installation to the System

Blankfont.C installs corrupted system binaries into the C:\ drive of the phone. When the phone boots these corrupted binaries will be loaded instead of the correct ones, and the phone will crash at boot.