1. Symantec/
  2. Security Response/
  3. Android.Backapp


Risk Level 1: Very Low

September 27, 2012
September 27, 2012 10:19:14 AM
Systems Affected:
Android package file
The Trojan may arrive as a package with the following characteristic:

Package name: com.androidkernel.flash

When the Trojan is being installed, it requests permissions to perform the following actions:
  • Access extra location provider commands
  • Access location information, e.g. Cell-ID, WiFi, GPS
  • Access power management
  • Access the camera device
  • Allow read-only access to phone state
  • Create mock location providers for testing
  • Disable the keyguard
  • End background processes
  • Initiate a phone call without going through the Dialer user interface for the user to confirm that the call is being placed
  • Modify global audio settings
  • Modify the phone state, e.g. turn on or off
  • Monitor incoming SMS messages, to record or perform processing on them
  • Monitor, modify, or abort outgoing calls
  • Open network sockets
  • Read or write the system settings
  • Read the low-level system log files
  • Read the user's contacts data
  • Read, write, and send SMS messages
  • Receive the ACTION_BOOT_COMPLETED message that is broadcast after the system finishes booting
  • Record audio
  • Restart packages
  • Update device statistics
  • Use the PowerManager WakeLocks to keep the processor from sleeping or the screen from dimming
  • Write (but not read) the user's contacts data
  • Write to an external storage device

This Trojan must be installed manually. Once installed, it does not display an icon.

The Trojan installs itself as a system service on the device.

The Trojan creates the following receivers:
  • com.androidkernel.flash.b.br
  • com.androidkernel.flash.cm.SR

Next, it creates the following services:
  • com.androidkernel.flash.b.oo
  • com.androidkernel.flash.s.SE1
  • com.androidkernel.flash.s.SE2
  • com.androidkernel.flash.s.SE3
  • com.androidkernel.flash.s.SE4
  • com.androidkernel.flash.s.SE5
  • com.androidkernel.flash.s.SE6
  • com.androidkernel.flash.s.SE7
  • com.androidkernel.flash.s.SE8
  • com.androidkernel.flash.s.SE9
  • com.androidkernel.flash.s.SE10
  • com.androidkernel.flash.call.ca
  • com.androidkernel.flash.call.CR
  • com.androidkernel.flash.cm.SP
  • com.androidkernel.flash.task.TaskService

The Trojan then monitors for SMS messages containing the following string:

An SMS message containing the above string is a command from the remote attacker and these messages will not be displayed.

The Trojan may then gather the following information from the device:
  • .3gp files
  • .amr files
  • .jpg files
  • GPS location
  • SMS messages

The above information is then sent to the remote attacker.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.
Writeup By: Tommy Dong
Summary| Technical Details| Removal

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