Backdoor:W32/PcClient.YW

Classification

Category :

Malware

Type :

Backdoor

Aliases :

Backdoor:W32/PcClient.YW

Summary

A remote administration tool (RAT) that bypasses the security features of a program, computer or network to give unauthorized access or control to its user.

Removal

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

Backdoor:W32/PcClient.YW attempts to hide processes, files, and registry data. It allows the attacker to perform arbitrary actions on the infected machine. Backdoor:W32/PcClient.YW also has a rootkit functionality and steals sensitive information from an infected computer.

Installation

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

  • %programfiles%\internet explorer\connection wizard\zhyrikwo.dll - backdoor
  • %programfiles%\internet explorer\connection wizard\zhyrikwo.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 explorer\connection wizard\zhyrikwo.sys - rootkit

Activity

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:

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

RegistryIt modifies the following known registry entry as its autostart technique: Data before:

  • [HKLM\SYSTEM\CurrentControlSet\Services\sens\Parameters] ServiceDll = %sysdir%\sens.dll

Data after:

  • [HKLM\SYSTEM\CurrentControlSet\Services\sens\Parameters] ServiceDll = %programfiles%\internet explorer\connection wizard\zhyrikwo.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:

  • [HKLM\System\ControlSet001\Services\zhyrikwo] ImagePath= %programfiles%\internet explorer\connection wizard\zhyrikwo.sys