Threat description




Worm:W32/Agent.BTZ: Worms are computer programs that replicate independently by copying themselves to other systems.


Automatic action

Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.

More scanning & removal options

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

You may also refer to the Knowledge Base on the F-Secure Community site for more information.

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Technical Details

Creates these files:

The files "winview.ocx" and "mswmpdat.tlb" holds the log of the files and their location that the malware has installed. The content of these file are encrypted. The file "muxbde40.dll" is the malware itself with a different name.

Spreading function

The worm spreads by creating an AUTORUN.INF file to the root of each drive with the malicious .dll file. The contents of the file are as follows:

shell\open\Command=rundll32.exe .\\[RANDOM].dll,InstallM

Note: [RANDOM] represents a random name that the worm creates for the dll. If the malware detects a new partition, or usb stick for example, it will get infected immediately. The registry keys are used to make sure that the malware gets launched when the computer starts.

File System Changes

Creates these files:

  • %windir%\system32\muxbde40.dll
  • %windir%\system32\winview.ocx
  • %temp%\6D73776D706461742E746C62FA.tmp
  • %windir%\system32\mswmpdat.tlb
Network Connections

Attempts to download files from:

  • https://worldnews.ath.cx/update/img0008/[REMOVED].jpg
Registry Modifications

Sets these values:

  • HKLM\Software\Classes\CLSID\{FBC38650-8B81-4BE2-B321-EEFF22D7DC62} (default) = Java.Runtime.52
  • HKLM\Software\Classes\CLSID\{FBC38650-8B81-4BE2-B321-EEFF22D7DC62}\InprocServer32\ (default) = C:\WINDOWS\system32\muxbde40.dll
  • HKLM\Software\Classes\CLSID\{FBC38650-8B81-4BE2-B321-EEFF22D7DC62}\InprocServer32\ ThreadingModel = Apartment
  • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\ShellServiceObjectDelayLoad\ UpdateCheck = {FBC38650-8B81-4BE2-B321-EEFF22D7DC62}

Creates these keys:

  • HKLM\Software\Microsoft\Windows\CurrentVersion\StrtdCfg
  • HKLM\Software\Classes\CLSID\{FBC38650-8B81-4BE2-B321-EEFF22D7DC62}
  • HKLM\Software\Classes\CLSID\{FBC38650-8B81-4BE2-B321-EEFF22D7DC62}\InprocServer32\

Description Created: 2008-06-26 15:41:53.0

Description Last Modified: 2008-06-26 16:54:32.0

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