Trojan-Downloader.Win32.Small.yk

Technical Details

This Trojan downloads files via the Internet without the user's knowledge or consent.

The Trojan itself is a Windows PE EXE file 3584 bytes in size, written in Visual C++ and packed using UPX. The unpacked file is approximately 14KB in size.

Payload

Once launched, the Trojan registers itself in the system registry, ensuring the the file will be launched each time Windows is rebooted on the victim machine:

The Trojan is able to download and launch other files on the victim machine.

The Trojan downloads a file called bombmp3.exe from http://www2.f***gstone.com/softwares/ and saves it to the Windows root directory:

This file is then launched for execution.

Removal instructions

1. Delete the original Trojan file (the location of this file will vary, depending on how the victim machine became infected).
2. Delete the file downloaded by the Trojan:
   %Windir%\bombmp3.exe
3. Delete the following key from the system registry:
   [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
    "mswspl"="<path to Trojan file>"
4. Update your antivirus databases and perform a full scan of the computer (downloada trial version of Kaspersky Anti-Virus).