Threat Description



Aliases: Trojan:​SymbOS/CDropper.A, Trojan:​SymbOS/CDropper.A, SymbOS/Cabir.Dropper
Category: Malware
Type: Trojan
Platform: SymbOS


A trojan, or trojan horse, is a seemingly legitimate program which secretly performs other, usually malicious, functions. It is usually user-initiated and does not replicate.


Automatic Disinfection

F-Secure Mobile Anti-Virus will detect the installed Cabir variants and delete the worm components.

After deleting worm files you can delete go to application manager and uninstall the fileNorton AntiVirus 2004 Professional.sis.

Alternative Installation of F-Secure Mobile Anti-Virus

If your phone is infected with some Cabir variant and you cannot install files over Bluetooth, you can download F-Secure Mobile Anti-Virus directly to your phone

  • Open web browser on the phone
  • Go to
  • Select link "Download F-Secure Mobile Anti-Virus" and select phone model
  • Download the file and select open after download
  • Install F-Secure Mobile Anti-Virus
  • Go to applications menu and start Anti-Virus
  • Activate Anti-Virus and scan all files

Technical Details

Trojan:SymbOS/CDropper.A infects mobile devices that run on the Symbian Series 60 operating system. On arriving on a clean device, it will install Cabir.E and Cabir.D into the device and disables the Bluetooth control application.


The original version of CDropper.A is distributed in a Symbian installation file deceptively named "Norton AntiVirus 2004 Professional.sis". When Cdropper.A is installed, it will drop files into the following directories:

  • \images\
  • \sounds\digital
  • \system\apps
  • \system\install
  • \system\recogs
  • \system\apps\btui
  • \system\apps\fexplorer
  • \system\apps\file
  • \system\apps\freakbtui
  • \system\apps\smartfileman
  • \system\apps\smartmovie
  • \system\apps\systemexplorer
  • \system\apps\[yuan]

CDropper.A installs different Cabir variants into several places in the device file system.

Some of the installed Cabirs replace common third party applications (FExplorer, SmartFileMan, Smartmovie and SystemExplorer) so that if user has one of those applications installed, it gets replaced with Bluetooth-Worm:SymbOS/Cabir.D and its icon in the menu will go blank.

If user clicks on one of the replaced icons in the menu, the Cabir.D that has replaced that application will start and try to spread to other devices. If Cabir.D starts, it will spread as Cabir.D ([YUAN].SIS) without other Cabir variants or Cdropper.A

CDropper.A will also install auto start component that tries to automatically start Cabir.D upon system reboot, but fails as the auto start component points into directory that is not installed on the device.

CDropper.A will also install non-functional version of the Bluetooth control application, so that user cannot change Bluetooth settings without disinfecting the device first.


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