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:
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.
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.
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.