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: Email-Worm

Email-Worms spread via email. The worm sends a copy of itself as an attachment to an email message or a link to its file on a network resource (e.g. a URL to an infected file on a compromised website or a hacker-owned website). In the first case, the worm code activates when the infected attachment is opened (launched). In the second case, the code is activated when the link to the infected file is opened. In both case, the result is the same: the worm code is activated. Email-Worms use a range of methods to send infected emails. The most common are: using a direct connection to a SMTP server using the email directory built into the worm’s code using MS Outlook services using Windows MAPI functions. Email-Worms use a number of different sources to find email addresses to which infected emails will be sent: the address book in MS Outlook a WAB address database .txt files stored on the hard drive: the worm can identify which strings in text files are email addresses emails in the inbox (some Email-Worms even “reply” to emails found in the inbox) Many Email-Worms use more than one of the sources listed above. There are also other sources of email addresses, such as address books associated with web-based email services.

Read more

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 Internet worm spreads via e-mail by sending infected messages from affected computers. While spreading, the worm uses MS Outlook and sends itself to all addresses that are stored in the MS Outlook Address Book. As a result, an infected computer sends as many messages to as many addresses stored in the MS Outlook Contacts List.

The worm is written in the scripting language "Visual Basic Script" (VBS). It works only on computers in which the Windows Scripting Host (WSH) has been installed. In Windows 98 and Windows 2000, WHS is installed by default. To spread itself, the worm accesses MS Outlook and uses its functions and address lists. This is available in Outlook 98/2000 only, so the worm is able to spread only in the case that one of these MS Outlook versions is installed.

When run, the worm sends its copies by e-mail and drops a Trojan program.


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

The Subject:


Message body:

Es de todos ya conocido el monopolio de Telef�nica pero no tan conocido los m�todos que utiliz� para llegar hasta este punto. En el documento adjunto existen opiniones, pruebas y direcciones web con m�s informaci�n que demuestran irregularidades en compras de materiales, facturas sin proveedores, stock irreal, etc. Tambi�n habla de las extorsiones y favoritismos a empresarios tanto nacionales como internacionales. Explica tambi�n el por qu� del fracaso en Holanda y qu� hizo para adquirir el portal Lycos. En las direcciones web del documento existen temas relacionados para que ech�is un vistazo a los comentarios, informes, documentos, etc. Como comprender�is, esto es muy importante, y os ruego que reenvi�is este correo a vuestros amigos y conocidos.

Attached file name:


Depending on the system settings, the real extension of the attached file (".vbs") may not be shown. In this case, a filename of the attached file is displayed as "TIMOFONICA.TXT".

Being activated by a user (by double clicking on the attached file), the worm opens MS Outlook, gains access to the Address Book, retrieves all of the addresses, and sends messages with its attached copy to all of them. The message subject, body, and attached file name are the same as above.

In addition, in each sent infected message, the worm sends another message to a randomly generated (numeric) address at the host "", for example "". The message contains the following:




informa que: Telef�nica te est� enga�ando.

In actuality, the "" is an SMS gate that sends SMS messages to phone numbers. The number is the prefix of the e-mail address in the message.

As a result, the worm tries to spam people with SMS messages. The worm sends as many SMS messages to random selected numbers as there are e-mails stored in the address book (the worm sends an SMS message per each infected e-mail message), also installing a Trojan program.

Installing a Trojan program

To install the Trojan program to the system, the worm creates a "" file in the Windows system directory, and writes a code (that stored in worms body) into the file. The worm then registers this file in the system registry in the auto-run section:

HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunCmos =

During the next Windows startup, the Trojan takes control, erases the CMOS information, and corrupts the information on the local disks.

The worm creates the file "C:TIMOFONICA.TXT" with the following content:

.... Tarifa plana de 6000 pts/mes. Extorsi�n. A principio de 1.998 tras un seguimiento de su gesti�n se descubrieron numerosas irregularidades en su gesti�n, amparadas hasta el momento, en el desconocimiento que nosotros ten�amos sobre Internet. Compras de materiales, que nunca apareci� por ning�n lado, pero si la factura del proveedor. .... Yo pienso que si Timofonica (ke a fin de kuentas es la due�a de Terra) kiere soltar dineros para una ONG, no le hace falta hacer este tipo de acto solidario, es mas, me parece misero y ridikula la kantidad de un millon de pesetas .. Son unos ridikulos de mierda, un millon de pesetas para ellos no es nada, pero un millon de hits en sus paginas mas a final de mes supone una peke�a subidita en las acciones de Terra en Bolsa. Total, ke Terra no son las Hermanitas de los Pobres (pobres monjas, kompararlas kon los chupasangres de Timofonica), NI NOSOTROS SEMOS GILIPOLLAS !!! Podran decir ke estamos obsesionados, ke tamos en kontra de Timofonika, ke protestamos por vicio, PERO ES KE EN 3 ATOS KE LLEVO EN INET SOLO LA HAN KAGADO UNA VEZ TRAS OTRA !! SI ES KE SE LO GANAN A PULSO !! Lo dicho , todo lo ke g#ele a Telefonica SUX, o en castellano tradicional , APESTA ! ....


Visita estas p�ginas. Est�s inivitado.

Then, the worm modifies system registry to display this file content (in Notepad window) instead of run any VBS file.

To restore normal functionalty for VBS files association you may run in Command Prompt window following instruction:


Read more

Find out the statistics of the vulnerabilities spreading in your region on

Found an inaccuracy in the description of this vulnerability? Let us know!
Kaspersky Next
Let’s go Next: redefine your business’s cybersecurity
Learn more
New Kaspersky!
Your digital life deserves complete protection!
Learn more
Confirm changes?
Your message has been sent successfully.