Threat description



Skulls.J is minor variant of Skulls.D trojan. The main difference between Skulls.J and Skulls.D is that the Skulls.J doesn't drop any cabir variants directly. The Skulls.J drops SymbOS/AppDisabler.A trojan, which drops Cabir.Y and Locknut.B on the device.


Automatic action

Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.

More scanning & removal options

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Technical Details

In addition of dropping the AppDisabler.A the Skulls.J tries to disable F-Secure Anti-Virus and other Anti-Virus applications.

F-Secure Anti-Virus protected from the trojan attack as it is capable of detecting the trojan using generic detection, which was created long before this trojan surfaced.

Spreading in: Skulls.J trojan SIS file has been manually inserted into several different pirate copied games and applications. However none of these files have been detected in the wild.


Tries to disable Anti-Virus and drops SymbOS/Appdisabler.A.

Skulls.J also contains application that displays animation of flashing skull picture. But unlike in Skulls.D, Skulls.J does not contain startup code for the animation, this code is introduced by AppDisabler.A, but is prevented from working by Locknut.B which is also dropped by Appdisabler.A.


Generic detection that detects Skulls.J was published for F-Secure Mobile Anti-Virus on December 13th, 2004 in

Detection Type: Mobile

Database: database build number 15

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