the items aren't "hacked" people abused a feature added in 1.7 that was sorta hidden it was meant for adventure / custom maps it was item attributes which made it while holding an item you could have certain attributes added your player EG; extra hearts, speed, flight. There is youtube videos explaining how to do it. The people who exploited it watched youtube to figure out how to do it. all they had to do to make you crash was change one variable that all videos said not to mess with due to inevitable crashing when held. the owners don't know which one has since then disallowed the command it was used doing /item.
