The Zombie Rot was one of he types of Zombie-type creatures that were formerly deceased bluepills. These act as mobs in the Halloween Masquerade Event in the Matrix Online, along with the Zombie Curse. Both redpills and bluepills can be infected alike, once a redpill (and maybe bluepills) get infected, they need to immediately take an antiotic to cure themselves of the virus. The Zombies have a weakness for holy water.