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 a worm written in Visual Basic Script language (VBS). This worm spreads via e-mail and IRC (Internet Relay Chat) channels.

Being executed, the worm script creates a new script file "RUNDLL.VBS" in the Windows system folder, and modifies the system registry to execute this script upon every Windows start-up.

Then the worm displays the following message box:

This will add a shortcut to free XXX links on your desktop. Do you want
to continue?

If a user answers is "YES," the worm creates a shortcut on the desktop with URL to XXX site.

Then the worm enumerates all network drives on a computer, and copies infected script to the root directory of each network drive.

To spread via e-mail, the worm uses MS Outlook. The worm's spreading routine is very similar to a such routine in the "Melissa" virus, and works in the same way. The message with the infected worm script contains attached worm script (LINKS.VBS).

The message subject: Check this
The message body:    Have fun with these links.

The "RUNDLL.VBS" script, when run creates, another script file "LINKS.VBS" in the Windows directory (LINKS.VBS is the same script as described above). Then it scans all fixed drives for folders "MIRC", "PIRCH98", "Program Files" (the folder where most Windows programs usually are installed) and also all their subfolders, and searches for the "MIRC32.EXE" or "PIRCH98.EXE" programs (popular IRC clients). If any of these programs are found, the worm creates a script file (SCRIPT.INI for MIRC or EVENTS.INI for PIRCH) that contains commands to send an infected "LINKS.VBS" to other IRC users when they join the same IRC channel to which an infected computer is connected.

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