Once the Backdoor:W32/PcClient.YW had been executed, it will drop its components in the following path and filename:

• %programfiles%internet explorerconnection wizardzhyrikwo.dll - backdoor
• %programfiles%internet explorerconnection wizardzhyrikwo.drv - keylogger

Note: the file size of zhyrikwo.dll might vary due to garbage code appended at the end of the file.


It will also drop the following driver that will communicate with the .dll files in order to hide the malware processes, registry entries and files:

• %programfiles%internet explorerconnection wizardzhyrikwo.sys - rootkit

It modifies the following known registry entry as its autostart technique:

Data before:

• [HKLMSYSTEMCurrentControlSetServicessensParameters]

ServiceDll = %sysdir%sens.dll

Data after:

• [HKLMSYSTEMCurrentControlSetServicessensParameters]

ServiceDll = %programfiles%internet explorerconnection wizardzhyrikwo.dll


The file zhyrikwo.dll will intercept any access to the original file, sens.dll. as a stealth mechanism, and after executing its malicious routines, will transfer the correct parameters to sens.dll.


It also adds the following autostart registry entry for the driver:

• [HKLMSystemControlSet001Serviceszhyrikwo]

ImagePath= %programfiles%internet explorerconnection wizardzhyrikwo.sys


Note: This rootkit can be detected by F-Secure's BlackLight.


Part of its payload is that it logs all the keystrokes made by the user and sends this file to a remote hacker.

Another part of the payload is that it has a backdoor component. The backdoor routine is injected into svchost.exe, which is capable of doing the following:

• updating itself
• remote execution

This malware connects to the following site:

http://dynsev5299.2mydns.com/i[BLOCKED]x.asp

Last update 12 March 2007

 

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