One way they can be obtained is called clear-text sniffing. Social Engineering is probably the easiest way to obtain passwords. This is simply a method of calling the target and simply conning them into giving out their password. Usually intruders will call large companies, find vulnerable people, claim to be in the IS department, and ask for the password. This technique is very common.
Passwords are the foundation of computer security.
Because software is constantly evolving, security is an endless process. From time to time systems are compromised because one vulnerability is overlooked. An entire section is devoted to handling events such as break-ins, DoS attacks, and computer security law. Events that look like system intrusion may actually be software configuration errors. If an intrusion is suspected, react quickly by terminating the network connection.