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Danmec.c

This page shows details and results of our analysis on the malware Danmec.c

Threat Detail

Malware Type: Trojan

Malware Sub-type: Dropper

Discovery Date: 2009-09-22

Next Steps:

Overview

---Update on September 23, 2009---
The risk assessment of this threat has been updated to Low-Profiled due to media attention at:
http://www.theregister.co.uk/2009/09/21/razer_distributes_malware/
--

Droppers are files which contain other binaries within their body. They act like a self-extracting ZIP file - taking the files stored inside and then installing them on the affected machine.

The types of files which are dropped by many droppers include other Trojans (such as Downloaders) to download yet more files from the remote machine, BackDoors to allow the hacker remote access to the client machine as well as Dialers to change the dial-up settings of the client's Internet connection, normally to premium rate number.


Minimum DAT

5751 (2009-09-24)

Updated DAT

5751 (2009-09-24)

 Minimum Engine

5.3.00

File Length

Varies

 Description Added

2009-09-22

Description Modified

2009-09-23

Malware Proliferation

Characteristics

---Update on September 23, 2009---
The risk assessment of this threat has been updated to Low-Profiled due to media attention at:
http://www.theregister.co.uk/2009/09/21/razer_distributes_malware/
--

When run, this Trojan drops multiple maliciousfiles on the victim's machine. The names and locations of the files include the following:

  • Current directory
  • %WINDIR%\nod_x32.txt
  • %WINDIR%\system32\usbctl.exe
  • %WINDIR%\Temp\_check32.bat
  • %WINDIR%\Temp\~9.tmp (this filename can vary)
  • %WINDIR%\Temp\~C.tmp
  • %WINDIR%\Temp\xewtsirbvr.tmp (this filename can vary)

Here %WINDIR% is the user's Windows directory, usually C:\Windows.

The dropped files are detected as Danmec.c, Downloader-BVX, and Generic Dropper.kz.

The Trojan also creates the following registry key to start one of the dropped files as a service:

  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\usbctl

Symptoms

The presence of the above-mentioned files and registry keys.

Method of Infection

Droppers are not viruses, and as such do not themselves contain any method to replicate. However they may themselves be downloaded by other viruses and/or Trojans to be installed on the user's system.

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