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: 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 a non-memory resident parasitic Win32 virus with IRC spreading abilities. The virus searches for EXE, SCR, CPL, and OCX Windows executable files, and writes itself to the end of the file. There is only one virus version known, which is a "debug" version, and it infects these files only in when their names begin with the "1" character (for example, "1.EXE"). The virus looks for files in current, Windows, and Windows system directories.

To spread via IRC channels, the virus creates an infected C:MUTT.EXE file and overwrites SCRIPT.INI and EVENTS.INI files (mIRC and PIRCH control files) with commands that send a virus copy (MUTT.EXE file) to anyone entering the affected chat channel.

The virus uses anti-debugging tricks, and halts the system if its code is under debugger.

On the 15th of any month, the virus, by modifying the system registry, makes A: and B: drives invisible in Explorer. Then it displays the following message box:

[Win32.Mutt v1.00]
Mutt by ULTRAS[MATRiX] (c) 2000
Thanx: [MATRiX] VX TeAm: mort, NBK, anaktos, Del_Armg0, Lord Dark...
Greetz: all VX scene

The virus deletes the following anti-virus data files:


The virus also contains a routine that terminates anti-virus scanners and resident monitors, but this routine never receives control. The list of anti-virus programs appears as follows:

AVP Monitor
Amon Antivirus Monitor
AVG Control Center
Avast32 -- Rezidentn� podpora
Antiv�rusov� monitor Amon
Norton AntiVirus

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