Threat Descriptons



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BZub.DN, a variant of BZub, is a Trojan. BZub.DN creates files in the Windows directory and steals logins, passwords, PINs, check words and other info related to logging to bank websites.


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

The BZub.DN trojan was spammed to a large number of people as an attachment to an email message. The attachment name was rechnung.exe, the same file name that was recently used for a spammed variant of Haxdoor backdoor. The trojan drops a keylogger and spies against users of several banks.After being run by the user, the trojan drops three files to the Window System folder. The dropped files represent the main spying component (ipv6monl.dll) and a keylogger (msn.exe and hook.dll). Both spying components are registered to start with every Windows session and remain active in memory at all times. The main spying component steals information related to various on-line banking accounts. Customers of the following banks and on-line payment systems may be affected:

  • Barklays
  • E-Gold
  • Intelligent Finance
  • Nationwide's Internet Bank
  • Postbank

The trojan also steals the following info and sends it to a hacker:

  • HTTP mail password
  • HTTP mail user name
  • IE autocomplete fields data
  • IE protected storage data
  • MSN Explorer signup data
  • Outlook account passwords
  • POP server name
  • POP server password
  • POP server user name
  • SMTP email address

The keylogger records all keystrokes on an infected computer and sends the stolen info to the hacker.

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