Most of us are familiar with the virus
that used to block Orkut and Youtube websites. If you are curious about
creating such a virus on your own, here is how it can be done.
As usual I am using
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 this virus
program. When this program is executed, it will block all those websites that
are listed in the source code. In the following example, the sites that are
listed in the source code are Google, Yahoo and Youtube. When you download the
source code of this program, you have a choice to include your own list of
sites that you want this virus to block.
I have just removed the source code of
this program from this post as it is lengthy and makes the post look messy. You
can still download the source code of this virus program from the following
link:
How it Works?
The Windows operating system maintains
a special file called HOSTS which can be used to block any given hostname or
domain name (website) by adding new entries onto it. This program works by
modifying the HOSTS file by adding new entries of those sites that are intended
to be blocked. The HOSTS file is located at:
%windir%\system32\drivers\etc (Usually:
C:\windows\system32\drivers\etc)
So, when you execute this program, all
it does is add the entries of the list of those sites (mentioned in the source
code) to this HOSTS file. Once this is done, the site will be blocked from your
computer. So, none of the browsers would be able to load those sites on your
computer.
For more information
on HOSTS file, I recommend reading my other post on How to use HOSTS file to block websites.
Now, as far as the technical part of
this program is concerned, people who have a working knowledge of ‘C’ should be
easily able to understand the working of this virus program. However, for those
who are new to ‘C’ programming, here is the algorithm of this program:
·
Determine the Root drive. ie: Find the drive (C:, D:, E: or F:) on which
the Windows is installed.
·
Navigate to: %windir%\system32\drivers\etc
·
Open/Load the HOSTS file.
·
Copy a list of those websites that are mentioned in the ARRAY to the END
of the file.
·
Save the file and Exit.
How to Compile the Source Code?
For a step-by-step
compilation guide, refer my post: How
to compile C Programs?
Testing the Virus:
1. To test, run the
compiled module. It will block the sites that are 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 command in 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.
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