Net-Worm.Win32.Bizex

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.

Propagation

On connecting to the site

http://www.jokeworld.xxx/xxx.html

(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:

[HKLMSoftwareMicrosoftWindowsCurrentVersionRun]
  "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 Bred.fr > Espace Bred.fr
American Express UK - Personal Finance
Banamex.com
baNK
Banque
Banque en ligne
Barclaycard Merchant Services
Collegamento a Scrigno
Commercial Electronic Office Sign On
Credit Lyonnais interacti
CyberMUT
E*TRADE Log On
e-gold Account Access
Home Page Banca Intesa
LloydsTSB online - Welcome
Merchant Administration
Page d'accueil 
Secure User Area
SUNCORP METWAY
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: www.ustrading.info

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

java32.dll
javaext.dll
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.

Other

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.