Threat description


DATE DISCOVEREDAugust 22, 2006


BZub.BL is a member of the BZub family of trojan spies.These types of trojans compromise system security by providing authentication information (logon, passwords, credit card numbers, etc.) to malicious users. This trojan steals the logon information of some Online German Bank accounts. Aside from that, it also steals e-mail accounts and passwords that are stored in the user's computer system.BZub.BL is downloaded and executed by Small.DOG.


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Technical Details

BZub.BL is downloaded and executed by Small.DOG from the following URL:


Once BZub.BL is executed, it drops a file named Ipv6mons.dll into the Windows Systems Directory. It adds several encrypted or random registry values under the following subkey as its auto start technique:

  • [SOFTWARE\Microsoft\Windows\CurrentVersion\Control Panel\load]

The registry values are the following:

  • cmpid
  • forwas
  • h
  • net_insll
  • nw
  • worg
  • wspopp

Moreover, it registers itself as a Browser Helper Object (BHO) using the following registry entries:

  • [HKEY_CLASSES_ROOT\CLSID\\InprocServer32] @ = "{systemdir}\ipv6mons.dll"
  • [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\\InprocServer32] @ = "{systemdir}\ipv6mons.dll"

It also registers its Internet Explorer as an authorized application to prevent the Windows Firewall from blocking network transactions through the said program:

  • [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess \Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List] "{Program Files}\Internet Explorer\IEXPLORE.EXE" = "{Program Files} \Internet Explorer\IEXPLORE.EXE:*:Enabled:Internet Explorer"

BZub.BL also makes a copy of the existing file C:\ to C:\ewerufeassur8fr. It deletes the following files:

  • C:\clearsdingdrfive
  • C:\test.txt

It creates a file named info.txt containing information about the infected system:

  • Computer ID
  • Computer name
  • Country/Region
  • IP Address
  • Windows version

BZub.BL steals information about the following by monitoring websites/forms and querying some registries:

  • Bank logon details
  • Cache password
  • Hotmail smtp/pop3 server
  • IEAutoCompleteFields
  • MSN Explorer Signup
  • Outlook Express

It steals the logon details of bank account users that have the following strings:

  • app/
  • app/
  • https://*
  • https://signin.ebay*/ws/eBayISAPI.dll

BZub.BL sends gathered information via FTP using any of the following files:

  • form.txt
  • info.txt
  • shot.txt

Detection Type: PC

Database: 2006-08-21_02

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