Parent class: VirWare

Viruses and worms are malicious programs that self-replicate on computers or via computer networks without the user being aware; each subsequent copy of such malicious programs is also able to self-replicate. Malicious programs which spread via networks or infect remote machines when commanded to do so by the “owner” (e.g. Backdoors) or programs that create multiple copies that are unable to self-replicate are not part of the Viruses and Worms subclass. The main characteristic used to determine whether or not a program is classified as a separate behaviour within the Viruses and Worms subclass is how the program propagates (i.e. how the malicious program spreads copies of itself via local or network resources.) Most known worms are spread as files sent as email attachments, via a link to a web or FTP resource, via a link sent in an ICQ or IRC message, via P2P file sharing networks etc. Some worms spread as network packets; these directly penetrate the computer memory, and the worm code is then activated. Worms use the following techniques to penetrate remote computers and launch copies of themselves: social engineering (for example, an email message suggesting the user opens an attached file), exploiting network configuration errors (such as copying to a fully accessible disk), and exploiting loopholes in operating system and application security. Viruses can be divided in accordance with the method used to infect a computer:
  • file viruses
  • boot sector viruses
  • macro viruses
  • script viruses
Any program within this subclass can have additional Trojan functions. It should also be noted that many worms use more than one method in order to spread copies via networks.

Class: Virus

Viruses replicate on the resources of the local machine. Unlike worms, viruses do not use network services to propagate or penetrate other computers. A copy of a virus will reach remote computers only if the infected object is, for some reason unrelated to the virus function, activated on another computer. For example: when infecting accessible disks, a virus penetrates a file located on a network resource a virus copies itself to a removable storage device or infects a file on a removable device a user sends an email with an infected attachment.

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Platform: VBS

Visual Basic Scripting Edition (VBScript) is a scripting language interpreted by Windows Script Host. VBScript is widely used to create scripts on Microsoft Windows operating systems.


Technical Details

This is an Internet-worm written in Visual Basic Script language (VBS). It spreads using MS Outlook Express.

This worm spreads via e-mail by sending infected messages from infected computers. While spreading, the worm uses MS Outlook Express and sends itself to all addresses stored in the Windows Address Book. As a result, an infected computer sends as many messages to as many addresses kept in the Windows Address Book.

It works only on computers on which the Windows Scripting Host (WSH) is installed. In Windows 98 and Windows 2000, WHS is installed by default.

The worm arrives to a computer as an e-mail message with the attached file "" that is the worm itself.

The infected message in the original worm version contains:

Subject = "FW: Symantec Anti-Virus Warning"
Body = ----- Original Message -----
From: []
To: []; [];
[]; [];
[>; [];
Subject: FW: Symantec Anti-Virus Warning
There is a new worm on the Net.
This worm is very fast-spreading and very dangerous!

Symantec has first noticed it on April 04, 2001.

The attached file is a description of the worm and how it replicates itself.

With regards,
F. Jones
Symantec senior developer

Upon activation, the worm creates a fake Symantec virus information page about the non-existing virus "VBS.AmericanHistoryX_II@mm" and displays it. Then it creates several files that are used later for spreading.

The first file is named "c:www.symantec_send.vbs" containing Visual Basic Script that instructs MS Outlook Express to send infected messages to all of the addresses in the Windows Address Book.

The second file "c:message.vbs" contains Visual Basic Script that on November 24th, displays the following message:

Some shocking news
Don't look surprised!
It is only a warning about your stupidity
Take care!

Both of these files are registered by the worm in the system registry in the autorun section. Thusly, these scripts gain control upon each Windows startup.

The worm also registers a fake-virus information page as the start page of Internet Explorer.

To avoid duplicate spreading from the same machine, the worm creates "HKLMSOFTWAREMicrosoftWABOE Done" in the system registry key and sets its value to "Hardhead_SatanikChild". In this way, it does not spread from the same machine twice.

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