Fork Bomb

Fork Bomb The virus everyone knows.

Fork Bomb

Another classic, A fork bomb is the equivalent of a DOS attack on your own system. It aims at depriving the system off it’s Random access memory, leaving none for vital functions required to keep the systems running, hence crashing it. Just 5 characters long, the fork bomb is not Deadly to a computer, Just annoying.

As with the previous batch file virus tutorials, all you need to do is open up notepad, type and save the following code as a batch file, that is with extension .bat

%0|%0

(That was it.)
Technically, the above 5 characters are short for the following more comprehensible code :

:s
start %0
goto s

Here, the first line creates a sort of checkpoint called ‘s’. It can be used to bring the programs pointer to a specific command, as is done here by using ‘goto’ in the last statement. ‘%0′ is actually the name of the .bat file itself. So every time the loop is run another instance of the same program is called and then both of them run together, to again duplicate themselves.
If that seems too simple to cause any trouble, read on.

Every program doubling itself is a form of exponential growth. After one iteration of the loop, two programs are created. After another cycle, each of those two create another two for a total of four same programs. After 10 iterations we have 2^10 = 1024 programs. After 100 iterations we have 2^100 = 1.267 nonillion, a number so big you don’t even know what ‘nonillion’ is (It’s 10^30).

Even with today’s CPUs and RAMs being in the Giga Range(Ghz and Gb), the first program will probably not even complete 50 iterations before running out of memory. Mind you, every iteration would hardly take a few milliseconds , so running this file will almost definitely crash your computer.