Threat Description

AntiBTC

Details

Aliases: AntiBTC, IE0199, SNDVOL
Category: Malware
Type:
Platform: W32

Summary



A trojan named ie0199.exe was mailed to a large group of recipients in January 1999. The spammed messages were faked to look like coming from Microsoft and claimed to contain an update for Internet Explorer. The e-mail contained a 28kB big attachment called IE0199.EXE.



Removal



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Technical Details



The original mail looked like this:

Date: Mon, 25 Jan 1999 20:00:26 -0500
  From: "Microsoft Internet Explorer Support" IEsupport@microsoft.com
  To: "Microsoft Internet Explorer User"
  Subject: Please Upgrade Your Internet Explorer
    Microsoft Corporation
    1 Microsoft Way
    Redmond, WA 98052
    US
       Dear Sir/Madam
  As an user of the Microsoft Internet
  Explorer, Microsoft Corporation provides
  you with this upgrade for your web browser.
  It will fix some bugs found in your Internet
  Explorer. To install the upgrade, please save
  the attached file (ie0199.exe) in some folder
  and run it.
  For more information, please visit our
  web site at www.microsoft.com/ie/
  --------------------------------------------------------
  (c) 1995-1998 Microsoft Corporation. All Rights Reserved

When the IE0199.EXE file is run, it extracts two files from its body (MPREXE.DLL and SNDVOL.EXE) and copies them to the Windows system directory. Note: the MPREXE.EXE executable file (not a DLL) is one of the standard Windows file.

The trojan then registers the MPREXE.DLL file in the system to force the system to run this file on each reboot. The registration is done depending on the Windows version either in the system registry, or in the SYSTEM.INI file in [boot] section in the "drivers=" string. The MPREXE.DLL file is pointed as auto-executed.

When executed the MPREXE.DLL file just executes the SNDVOL.EXE file and exits. The SNDVOL.EXE file enables auto-dialing by changing the system registry Internet options, randomly selects one of three Bulgarian Web servers (www.btc.bg, www.infotel.bg, ns.infotel.bg), connects them and sleeps for some time. The trojan does not perform any other actions.

As a result, the trojan causes lots of network traffic both inside the infected company and at the Bulgarian servers. The trojan has probably been written to cause denial-of-service attacks for the Bulgarian systems.


Variant:PHO.EXE

PHOTOS17.EXE

This is the same trojan as described above, but it has been distributed with different names - and within different e-mails. Here's one sample e-mail:

Date:          Sat, 6 Mar 1999 07:24:32 +0200 (EET)
        From:          Lidia Steward LidiaSt27@aol.com
        To:friends
        Subject:       photos
        Hi,
    Look at the photos we talked about.
I have archived them with WinZip.
    Lidia
        Attachment: pho.exe

Apparently, such messages have been sent to thousands of unsuspecting internet users with a mass-mailing program. The pho.exe file is a extracting executable that will drop the same AntiBTC trojan as described above.

Do not open e-mail attachments sent by strangers.





Description Created: Analysis: Mikko Hypponen, Peter Szor, F-Secure, 1999


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