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W32/GetCodec

This page shows details and results of our analysis on the malware W32/GetCodec

Threat Detail

Malware Type: Virus

Malware Sub-type: Win32

Discovery Date: 2008-07-22

Next Steps:

Overview

This detection is for a virus that spreads by infecting media files.


Minimum DAT

5344 (2008-07-22)

Updated DAT

5993 (2010-05-25)

 Minimum Engine

5.2.00

File Length

varies

 Description Added

2008-07-22

Description Modified

2008-07-30

Malware Proliferation

Characteristics

When executed files of type WMA WMV and ASF throughout the system are modified by the trojan to include a url for required codec.  When the modified media files are played in Windows Media Player the player will recognize the additional directive in the modified file and attempt to connect to a remote URL (http://[removed].net?t=3) to download the required codec.  Instead of a codec the location contains a Trojan that is then downloaded an installed on the system.

At the time of analysis the file that media player downloaded from the remote URL was named windows_media_player_flash_codec_plugin.exe and is detected with current McAfee DATs as Nebuler.

Symptoms

The presence of media files containing a URLANDEXIT directive followed by a URL similar to the following format:

  • hxxp://xxxxx.net?t=3

x = alpha character [a-z]

Method of Infection

Distribution mechanisms can include IRC, peer-to-peer networks, newsgroup postings, or any way which media files are shared between computers.

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