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  Home / Viruses / Virus Encyclopedia

Trojan-Downloader.Win32.Small.ydh

Other versions: .cg, .cz, .dam, .hg, .jk, .jm, .s, .tnd, .tne, .tor, .tos, .yk, .yt, .yx

Detection added Jul 12 2008
Update released Jul 12 2008 12:21 GMT
Description added Feb 24 2009

Technical details

This Trojan downloads other files via the Internet and launches them for execution on the victim machine without the user’s knowledge or consent. It is a Windows PE EXE file. It is 34816 bytes in size. It is not packed in any way. It is written in C++.

Installation

Once launched, the Trojan copies its body to the Windows temporary directory as shown below:

%Temp%\hbgdown.exe
%Temp%\msdtc.exe

In order to ensure the Trojan is launched next time the system is started, it creates a service called “HTTP SSH”:

[HKLM\SYSTEM\CurrentControlSet\Services\HTTP SSH]
"DisplayName" = "HTTP SSH"
"ErrorControl" = "0"
"ImagePath" = "%Temp%\msdtc.exe"
"ObjectName" = "LocalSystem"
"Start" = "2"
"Type" = "10"
Payload

The Trojan downloads a file from the URL shown below:

http://*****gcdon.com.cn/v.exe

This file is saved to the Windows temporary directory as shown below:

%Temp%\gbn.exe

The downloaded file will then be launched for execution.

At the time of writing, the link was not active.

Removal instructions

If your computer does not have an up-to-date antivirus, or does not have an antivirus solution at all, follow the instructions below to delete the malicious program:

  1. Use Task Manager to terminate the Trojan process.
  2. Delete the following system registry key:
    [HKLM\SYSTEM\CurrentControlSet\Services\HTTP SSH]
  3. Delete the original Trojan file (the location will depend on how the program originally penetrated the victim machine).
  4. Delete the following files:
    %Temp%\hbgdown.exe
    %Temp%\msdtc.exe
    %Temp%\gbn.exe
  5. Delete all files from %Temporary Internet Files%.
  6. Update your antivirus databases and perform a full scan of the computer (download a trial version of Kaspersky Anti-Virus).
 

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