Threat Descriptons



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Aliases :

Skulls.U, SymbOS/Skulls.U


Skulls.U is a SIS file trojan that pretends to be installation file for Battery Extender software.


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

Spreading in: Ximplyfy Battery Extender.sis

When installed Skulls.U disables several built in applications, drops component files from Locknut.A, Doomboot.A and installs Cabir.B and Cabir.X

In addition of directly installing damaging files, Skulls.U also drops Locknut.C and MGDropper.A into the device.

Skulls.U also installs a pirate copied version of Simworks Anti-Virus into the device.

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Submit a Sample

Submit a file or URL for analysis.