Trojan.Win32.Agent.azsy

Technical Details

This malicious program is a Trojan. It is a Windows PE EXE file. It is 417792 bytes in size. It is packed using UPX. The unpacked file is approximately 439KB in size. It is written in C++.

Installation

Once launched, the Trojan copies its body to the current user’s Windows startup directory:

%Documents and Settings%\<user_name>\Main Menu\Programs\Startup\uninstall.exe

Payload

Once the victim machine has been rebooted, the Trojan extracts a file from itself. The file will have one of the names shown below:

%Documents and Settings%\<user_name>\Application Data\svchosts.exe
%Documents and Settings%\<user_name>\Application Data\taskmon.exe
%Documents and Settings%\<user_name>\Application Data\rundll.exe
%Documents and Settings%\<user_name>\Application Data\service.exe
%Documents and Settings%\<user_name>\Application Data\sound.exe
%Documents and Settings%\<user_name>\Application Data\upnpsvc.exe
%Documents and Settings%\<user_name>\Application Data\lsas.exe
%Documents and Settings%\<user_name>\Application Data\logon.exe
%Documents and Settings%\<user_name>\Application Data\helper.exe
%Documents and Settings%\<user_name>\Application Data\event.exe
%Documents and Settings%\<user_name>\Application Data\dumpreport.exe
%Documents and Settings%\<user_name>\Application Data\msiexeca.exe

This file is 404992 bytes in size. It will be detected by Kaspersky Anti-Virus as Trojan-Downloader.Win32.Agent.aoth.

In order to ensure that the Trojan is launched automatically each time the system is rebooted, the Trojan places a link to the file it extracted from its body in the system registry:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
"<rnd1>" = "<rnd2>"

<rnd1> is a name chosen from the list below:

CrashDump
EventLog
Init
lsass
Regscan
RunDll
Setup
Sound
svchosts
System
TaskMon
UPNP
Windows

<rnd> is the path to the file extracted from the Trojan shown in the list above.

Once the Trojan had delivered its payload, it will delete both its body and its copy "%Documents and Settings%\\Main Menu\Programs\Startup\uninstall.exe".

This Trojan will not run on Russian versions of Windows.

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 registrykey:
    [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
    "<rnd1>" = "<rnd2>"
  3. Delete the original Trojan file (the location will depend on how the program originally penetrated the victim machine).
  4. Delete the following files:
    %Documents and Settings%\<user_name>\Application Data\svchosts.exe
    %Documents and Settings%\<user_name>\Application Data\taskmon.exe
    %Documents and Settings%\<user_name>\Application Data\rundll.exe
    %Documents and Settings%\<user_name>\Application Data\service.exe
    %Documents and Settings%\<user_name>\Application Data\sound.exe
    %Documents and Settings%\<user_name>\Application Data\upnpsvc.exe
    %Documents and Settings%\<user_name>\Application Data\lsas.exe
    %Documents and Settings%\<user_name>\Application Data\logon.exe
    %Documents and Settings%\<user_name>\Application Data\helper.exe
    %Documents and Settings%\<user_name>\Application Data\event.exe
    %Documents and Settings%\<user_name>\Application Data\dumpreport.exe
    %Documents and Settings%\<user_name>\Application Data\msiexeca.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).