How To make A Trojan Horse VirusHow To make A Trojan Horse Virus

Most of you may be curious to know about how to make a Trojan or Virus on your own. Here is an answer for your curiosity. In this post I’ll show you how to make a simple Trojan on your own using C programming language.

This Trojan when executed will eat up the hard disk space on the root drive (The drive on which Windows is installed, usually C: Drive) of the computer on which it is run. Also this Trojan works pretty quickly and is capable of eating up approximately 1 GB of hard disk space for every minute it is run. So, I’ll call this as "C Drive Fucker". HAHA.

Before I move to explain the features of this Trojan you need to know what exactly is a Trojan horse and how it works.

The Trojan horse which I have made appears itself as an antivirus program that scans the computer and removes the threats. But in reality it does nothing but occupy the hard disk space on the root drive by just filling it up with a huge junk file. The rate at which it fills up the hard disk space it too high. As a result the the disk gets filled up to 100% with in minutes of running this Trojan. Once the disk space is full, the Trojan reports that the scan is complete. The victim will not be able to clean up the hard disk space using any cleanup program. This is because the Trojan intelligently creates a huge file in the Windows\System32 folder with the .dll extension. Since the junk file has the .dll extention it is often ignored by disk cleanup softwares. So for the victim, there is now way to recover the hard disk space unless reformatting his drive.
The algorithm of the Trojan is as follows
1. Search for the root drive
2. Navigate to WindowsSystem32 on the root drive
3. Create the file named “spceshot.dll”
4. Start dumping the junk data onto the above file and keep increasing it’s size until the drive is full
5. Once the drive is full, stop the process.
You can download the Trojan source code HERE. Please note that I have not included the executabe for security reasons. You need to compile it to obtain the executable.

Learn How To Compile A Program In C.


Testing:
To test the Trojan,  just run the SpaceEater.exe file on your computer. It’ll generate a warning message at the beginning. Once you accept it, the Trojan runs and eats up hard disk space.

How to remove the Damage and free up the space?
To remove the damage and free up the space, just type the following in the “run” dialog box.

%systemroot%\system32

Now search for the file “spceshot.dll“. Just delete it and you’re done. No need to re-format the hard disk.

NOTE: You can also change the ICON of the virus to make it look like a legitimate program. This method is described in the post: How to Change the ICON of an EXE file ?