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: Net-Worm

Net-Worms propagate via computer networks. The distinguishing feature of this type of worm is that it does not require user action in order to spread. This type of worm usually searches for critical vulnerabilities in software running on networked computers. In order to infect the computers on the network, the worm sends a specially crafted network packet (called an exploit) and as a result the worm code (or part of the worm code) penetrates the victim computer and activates. Sometimes the network packet only contains the part of the worm code which will download and run a file containing the main worm module. Some network worms use several exploits simultaneously to spread, thus increasing the speed at which they find victims.

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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 worm uses the Internet instant messaging system ICQ to spread via the Internet.

The worm sends ICQ users a message with a URL, which is linked to a file which contains procedures to automatically download and execute the malicious component of the worm on the victim computer.


On connecting to the site
(x here is used to replace certain characters) the CHM-exploit-a is used. The result of this is that a specially constructed CHM file is automatically executed on the victim computer. This file contains another file named 'iefucker.html'; this file contains TrojanDropper, a type of Trojan written in script language. This Trojan extracts a file named WinUpdate.exe from itself to a range of system directories.

In Windows 2000 and Windows XP:

C:Documents and SettingsAll UsersStart MenuProgramsStartupWinUpdate.exe
and in Windows 98:
c:windowsStart MenuProgramsStartupWinUpdate.exe
WinUpdate.exe is a Trojan program of the TrojanDownloader group, which downloads the main component of the worm from a remote site, and writes it to the temporary directory under the name aptgetupd.exe.

Main component

Aptgetupd.exe is a PE.EXE file, of approximately 84KB (86528 bytes) in size, packed using PECompact.

Once executed, the worm copies itself under the name sysmon.exe to the SYSMON sub-directory in the Windows system directory, and registers this file in the system registry auto-run key:

  "sysmon" = %system%sysmonsysmon.exe
The worm has a theft function which enables it to steal information relating to a range of financial services:
Acceso a Banca por Internet
Accueil > Espace
American Express UK - Personal Finance
Banque en ligne
Barclaycard Merchant Services
Collegamento a Scrigno
Commercial Electronic Office Sign On
Credit Lyonnais interacti
e-gold Account Access
Home Page Banca Intesa
LloydsTSB online - Welcome
Merchant Administration
Page d'accueil 
Secure User Area
Tous les produits et services
VeriSign Partner Manager
VeriSign Personal Trust Service
Wells Fargo - Small Business Home Page
It also steals data transmitted by HTTPS, relating to accounts of a variety of mail services such as Yahoo, etc.

All stolen information is saved in the files ~pass.log, ~key.log and ~post.log and is sent by FTP to a remote server:

The worm extracts a number of .dll files from itself and installs them in the Windows system directory:

icq_socket.dll (library used to send messages via ICQ)
ICQ2003Decrypt.dll (ICQ library)
The worm gains access to the ICQ contact list, disconnects the ICQ client which has been launched, connects to the server under the name of the user of the infected machine, and sends all contacts found a link to its own site.


In addition to the CHM exploit, when the link is opened, an attempt will be made to download and execute a Java archive, which contains a range of TrojanDownloaders (detected as Trojan.Java.ClassLoader and TrojanDownloader.Java.OpenConnection) which also attempt to download the components of the worm to the victim computer.

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