Alternatively referred to as a rabbit virus and wabbit, a fork bomb is a denial of service attack (DDoS). The fork bomb works by creating a new process, which repeatedly creates new processes. Each new process starts a new process, and the bomb then utilizes all available resources until there are no resources left. This attack is very effective in reducing a system's available resources and makes the system inaccessible and unusable.
One method of preventing fork bombs is to limit the amount of processes each user can open. For example, if a user was limited to having 40 processes running, the fork bomb would hit the 40 process limit quickly. Therefore, it would be unable to cause the system to run out of resources.