Trojan-Dropper.Win32.Small.fe

Technical Details

This Trojan is designed to install and launch other malicious programs on the victim machine without the user’s knowledge or consent. It is a Windows PE EXE file. It is 10784 bytes in size. It is packed using UPX. The unpacked file is approximately 22KB in size. It is written in C++.

Payload

When launching, the Trojan extracts the following file from its body and saves it to the Windows system directory:

This file is 8192 bytes in size. It will be detected by Kaspersky Anti-Virus as Backdoor.Win32.Thunk.f.

The Trojan also creates the following system registry keys:

[HKCU\Software\Classes\CLSID\{3F143C3A-1457-6CCA-03A7-7AA23B61E40F}\InProcServer32]
"(Default)" = "%System%\child.dll"
"ThreadingModel" = "Apartment"
[HKLM\Software\Microsoft\Windows\CurrentVersion\Explorer\SharedTaskScheduler]
"{3F143C3A-1457-6CCA-03A7-7AA23B61E40F}" = "OLE Automation Module"

If for some reason the Trojan is unable to create %System%\child.dll, it will save the malicious file as follows:

The system registry keys which the Trojan creates will correspond to this location.

The Trojan then calls this file's "load" function and ceases running.

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. Delete the original Trojan file (the location will depend on how the program originally penetrated the victim machine).
2. If the following files are present on the computer, delete them:
   %System%\child.dll
   %AppData%\Microsoft\child.dll
3. Delete the following system registrykeys:

   [HKCU\Software\Classes\CLSID\{3F143C3A-1457-6CCA-03A7-7AA23B61E40F}\InProcServer32]
   "(Default)" = "%System%\child.dll"
   "ThreadingModel" = "Apartment"
   [HKLM\Software\Microsoft\Windows\CurrentVersion\Explorer\SharedTaskScheduler]
   "{3F143C3A-1457-6CCA-03A7-7AA23B61E40F}" = "OLE Automation Module"

4. Update your antivirus databases and perform a full scan of the computer (download a trial version of Kaspersky Anti-Virus).