Hacking and griefing are some of potential problems that advertisers in virtual worlds should plan for. In October 2005, the entire Second Life grid was taken offline, overwhelmed by the load of self-replicating objects that have become known as Griefspawn (see article in The Escapist).
Griefing refers to players intentionally causing discomfort in other players and can be manifested in a variety of ways that range from verbal abuse to an assault by automated scripts that ruin the game experience or even crash the system. The results often are visually entertaining (at least to the griefer, if not the victim), and the scripts are fairly easy to acquire.
Second Life's Three Stages of Grief are:
(Note to the Lindens: the screengrabs were obtained in a controlled experiment and are not subject to abuse report.)
Trap incapacitates the attacked avatar (no movement or flying) whose only escape is to teleport to another sim.
Kill pushes avatar off with a splattering blood affect. Doesn't actually kill but is an annoyance. Often used in attacks against public events or clubs, pushing the public outside.
Orbit is the griefer's ultimate weapon. It throws the avatar up beyond the world's boundaries and into untextured space, in this case at the height of 8,126,796 meters. In the extreme cases, the orbit script also disables the teleport function and the player's only option is to restart the game.
Second Life, as I understand, actively polices the world and all abuse reports and subsequent actions are filed in the Police Blotter. Linden Lab punishes abusive players by warning, suspending, banning them from the game, or exiling them to a deserted corn field.
Image: Nimrod Yaffle for Clickable Culture