How to Create a Virus

Creating a virus is a process that can be very complicated or something that happens with a few button clicks (see Exercise 1). Advanced programmers may choose to code the malware from scratch. The less savvy or experienced may have to pursue other options, such as hiring someone to write the virus, purchasing code, or using an “underground” virus-maker application.

Exercise 1: Creating a Simple Virus

So: let’s write a simple virus. You need access to Notepad and bat2com, the latter of which you can find on the Internet:

Before you get started, here’s a warning: Do not execute this virus. This exercise is meant to be a proof of concept and for illustrative purposes only. Executing this code on your system could result in damage to your system that may require extensive time and skill to fix properly. With that said, follow these steps:

  1. Create a batch file called virus.bat using Windows Notepad.
  2. . Enter the following lines of code:
    @echo off
    Del c:\windows\system32\*.*
    Del c:\windows\*.*
  3.  Save virus.bat .
  4.  From the command prompt, use bat2com to convert virus.bat into .

Another way to create a virus is to use a utility such as JPS Virus Maker. It is a simple utility in which you pick options from a GUI and then choose to create a new executable file that can be used to infect a host. Figure 8.1 shows the interface for JPS Virus Maker.