Threat Descriptions

Worm:W32/Agent.BTZ

Classification

Category :

Malware

Type :

Worm

Platform :

W32

Aliases :

Worm:W32/Agent.BTZ

Summary

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

Removal

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

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: 

[autorun]
open=
shell\open=Explore
shell\open\Command=rundll32.exe .\\[RANDOM].dll,InstallM
shell\open\Default=1

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\