Threat description


Category: Malware
Type: Trojan
Platform: SymbOS
Aliases: Trojan:SymbOS/AppDisabler.A


Trojan:SymbOS/Appdisabler.A is a malicious SIS file dropper, which is dropped by the Skulls.J trojan.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.


More information on scanning and removal options available in your F-Secure product can be found in the Help Center.

You may also refer to the Knowledge Base on the F-Secure Community site for more information.

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details

Appdisabler.A tries to disable third party file managers and drops two other malwares:

  • Trojan:SymbOS/Locknut.B
  • Bluetooth-Worm:SymbOS/Cabir.Y.


When installed, AppDisabler.A will replace many third-party file managers as well as other third party applications with non-functional application files. It also drops Locknut.B and Cabir.Y onto the system.


When active, Appdisabler.A disables following applications:

  • EFileman
  • FExplorer
  • File
  • SmartFileManager
  • Smartmovie
  • SystemExplorer
  • Yewsprite
  • UltraMP3

The dropped malware Cabir.Y will not start automatically, but will attempt to start at the next boot. However, on most devices Locknut.B will cause application loading to fail. This prevent Cabir.Y from starting.

Appdisabler.A also contains a bootstrap component that attempts to start a component of Skulls.J showing animation of flashing skull. This functionality is also hampered by Locknut.B.


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