Threat description




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


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

More information on the 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.

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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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