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BackDoor-DNW

This page shows details and results of our analysis on the malware BackDoor-DNW

Threat Detail

Malware Type: Trojan

Malware Sub-type: Remote Access

Discovery Date: 2008-03-20

Next Steps:

Overview

BackDoor-DNW trojan provides remote access capabilities to an attacker by opening a backdoor on the compromised machine. The trojan is dropped by Exploit-TaroDrop.g, which exploits a vulnerability in JustSystem Ichitaro.


Minimum DAT

5256 (2008-03-20)

Updated DAT

6152 (2010-10-30)

 Minimum Engine

5.2.00

File Length

Varies

 Description Added

2008-03-20

Description Modified

2009-03-15

Malware Proliferation

Characteristics

Upon execution, the trojan drops following files:

  • %Systemdir%\WudfSvc.exe (Backdoor-DNW trojan)
  • %Systemdir%\fixmapi.dll (Backdoor-DNW trojan)
  • %Systemdir%\MSIMM.dll (Backdoor-DNW trojan)

The following registry key is modified:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run "WudfSvc" = "%Systemdir%\WudfSvc.exe"

It connects the following site and sends system information including computer name and OS version.

  • [removed].lightsut.com
  • port : 80

Then the trojan opens a backdoor. Backdoor has the following functions:

  • list files
  • provide remote shell (cmd.exe)
  • run programs

Symptoms

  • Existence of the Registry key described above
  • Outgoing traffic to the host [removed].lightsut.com port:80

Method of Infection

Backdoor-DNW is dropped by Expolit-TaroDrop.g trojan.

Removal

All Users:
Use current engine and DAT files for detection and removal.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

But in some particular cases, the following steps need to be taken.

Please go to the Microsoft Recovery Console and restore a clean MBR.

On Windows XP:

  • Insert the Windows XP CD into the CD-ROM drive and restart the computer.
  • When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
  • Select the Windows installation that is compromised and provide the administrator password.
  • Issue 'fixmbr' command to restore the Master Boot Record
  • Follow onscreen instructions.
  • Reset and remove the CD from CD-ROM drive.


On Windows Vista and 7:

  • Insert the Windows CD into the CD-ROM drive and restart the computer.
  • Click on "Repair Your Computer".
  • When the System Recovery Options dialog comes up, choose the Command Prompt.
  • Issue 'bootrec /fixmbr' command to restore the Master Boot Record.
  • Follow onscreen instructions.
  • Reset and remove the CD from CD-ROM drive.

Variants

United States - English