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.

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Platform: Win32

Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.


Technical Details

This is an Internet worm that spreads as an 8Kb MADCOW.EXE file attached to e-mail messages. To send infected messages, the worm uses MS Outlook. The worm also is able to send its copies to IRC channels by infecting an mIRC client.

First Run

When the worm is started for the first time (if a user clicks on the EXE attachment to the message, or accepts an IRC download), the worm copies itself to two files:

  • the Windows system directory with Wininet32.exe name
  • the Windows directory with MadCow.exe name

and registeres a MadCow.exe file in the auto-run section:

  • in the WIN.INI file, [windows] section, "run=" key - under Win9x
  • in the system registry in "Run=" key - under WinNT

The worm then creates a C:WIN32 directory and creates two files here (DOS batch file and VBS script program):

ENVOIE.BAT - it just spawns an ENVOIE.VBS file (next file)
ENVOIE.VBS - this script spreads the worm with infected messages

While spreading, the script connects to MS Outlook and sends infected e-mail messages to all addresses in the MS Outlook Address Book. The messages contain the following:

Subject: Pourquoi les vaches sont-elles folles ?
Body: Voila un rapport expliquant la folie des vaches
Attachment: MadCow.exe

Second Run

Upon the next start (next Windows restart), the worm creates its copy with the MadCow.exe name in the C:WIN32 directory, and then infects an mIRC client in the following directories:

C:Program FilesMIRC
C:Program FilesMIRC32

The infected mIRC client sends a worm copy (MadCow.exe file) to all users that join the infected channel.


The worm creates the registry key: HKLMSoftware[Atchoum]

If there is no mIRC client found in the system, the worm creates the MSLS.ICO file in the Windows system directory, writes there an image of imp (devil) and registers as a standard icon for EXE files.

The worm also contains the following text stings in its body:

IWorm.MadCow par PetiK (c)2000
I Love You Maya / Je t'aime

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