Worm

Contrary to a virus, a worm is not required to attach itself to an existing file to operate. It typically falters a network by consuming disk space and bandwidth, while a virus is capable of modifying information and destroying an entire operating system. While most worms are only intended to infect and cause little damage, some of them have shown to cause a significant disruption - a great example would be the Morris worm and Mydoom. These two worms raised concern due to their ability to install payloads that distribute other infections via email. A worm’s most common payload is to install a backdoor onto a compromised system and enable the creation of a zombie. Zombies are controlled by the worm writer and can actually be instructed to single out a targeted system and provoke a DOS attack. Aside from a reliable security application, the best way for a user to fend off worms and other infections is to remain wary of unsolicited email.