Threat Descriptons



Category :


Type :


Aliases :

Hobbes.A, SymbOS/Hobbes.A


Hobbes.A is a malicious SIS file trojan that drops corrupted binary that causes the application loader to crash on older phones that use Symbian OS.


Disinfection if user has not rebooted the phone

1. Uninstall the Symantec.sis using application manager

Disinfection is user has rebooted the phone

  • 1. Remove memory card from the phone and boot it again
  • 2. Install some file manager on the phone
  • 3. Go to the memory card and delete file \system\recogs\recAutoExec.mdl
  • 4. Uninstall the Symantec.sis using application manager

The Hobbes.A affects only phones that use Symbian OS version 6.1,which means that only old models such as Nokia NGage and Nokia 3650 are affected by the trojan.

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 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.

Technical Details

Hobbes.A pretends to be a pirated copy of Symantec Anti-Virus for Symbian phones. The installation package contains texts that instruct user to reboot after installation.

The corrupted binary in Hobbes.A causes OS to fail at boot so that none of the system applications are started. This means that all smartphone functionalities are disabled, calling and receiving calls on the phone works as normal.

Users who have a phone that is infected with Hobbes.A must not reboot their phone, as the damage caused by Hobbes.A is activated only on reboot.

Installation to system

When installed to the system the Hobbes.A installs corrupted version of FExplorer trying to disable FExplorer file manager, but fails as it installs it into incorrect directory.

Hobbes.A also installs several recognizer components to C: and E: drives, one of the components is a corrupted version of legitimate application which is missing it's other components and thus crashing on boot on older Symbian versions.

Spreading in: Symantec.SIS


Crashes the operating system application loading mechanism on reboot. Thus preventing applications menu or other programs from starting-

Exact detection was published in March 14th, 2005 in database build number 36.

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