Bizex worm spreads by sending an HTTP link to all ICQ contacts of an infected user. When a recipient clicks on a link, he/she is redirected to a website that has an HTML page with IFrame exploit. This exploit allows automatic execution of target files when Internet Explorer web browser is used. The HTML page concerned tries to autoexecute these 2 files:
The MEINE.SCM file is downloaded from the same site and the USER_BX.HTML file is downloaded from a different website. The USER_BX.HTML file downloads and tries to execute Java trojan downloader nocheat.jar (detected as Java/Bizex.A).
The Java/Bizex.A is used for downloading and executing two windows binaries and informing server where user_bx.html was downloaded whether operation was successful including users browser and user agent version information. The Java/Bizex.A tries to execute these 2 files:
The MEINE.SCM file is an ICQ sound scheme file that is dropped to a \Sounds subfolder located in the main ICQ directory. This sound scheme file contains a CHM archive inside its body. The CHM archive is then activated by the webpage and it drops and opens a file called IEF*CKER.HTM.
This file contains a Visual Basic Script code that drops a file WinUpdate.exe. This binary file is a trojan downloader. Depending on the Windows version the script saves the trojan downloader in a folder:
C:\Documents and Settings\All Users\Start Menu\Programs\Startup\WinUpdate.exe
By placing WinUpdate.exe in the startup folder, the script code makes sure that the trojan downloader is run during next Windows restart.
When it is activated, the trojan downloader copies itself as ALSDFKJ.EXE file to a temporary folder and then downloads and activates the main worm's component as APTGETUPD.EXE file. This file is downloaded to a temporary folder.
The main worm's component is a PE executable 86528 bytes long packed with PECompact file compressor. When it is run, it deletes its file from a temporary folder, creates SYSMON subfolder in Windows System folder and copies itself there with the SYSMON.EXE name. It also drops 4 files from its body to Windows system folder:
Additionally the XTEMPX.$ file is created in Windows System folder. Two of the dropped DLL files allow the worm to spread via ICQ, the other two are used to spy against an infected user. The worm creates a startup key for its file in the Registry:
"sysmon" = "%winsysdir%\sysmon.exe"
where %winsysdir% represents Windows System folder name. It should be noted that this Registry key can be only seen when Windows is started in Safe Mode as the worm uses stealth techniques to hide its Registry key.
The worm steals information from users of the following on-line services:
VeriSign Partner Manager
VeriSign Personal Trust Service
Commercial Electronic Office Sign On
Wells Fargo - Small Business Home Page
American Express UK - Personal Finance
Secure User Area
Barclaycard Merchant Services
Collegamento a Scrigno
Home Page Banca Intesa
Tous les produits et services
Banque en ligne
Credit Lyonnais interacti
Accueil Bred.fr > Espace Bred.fr
E*TRADE Log On
LloydsTSB online - Welcome
Acceso a Banca por Internet
e-gold Account Access
Additionally the worm records user's keystrokes on an infected computer and monitors his/her HTTP traffic. The stolen data is copied to the following files:
These files are then uploaded by the worm to an ftp site, that mot likely belongs to the worm's author.
To disinfect a computer from this worm it's enough to delete its files from a hard drive. Manual disinfection should be performed in Safe Mode.