Security policies are also important in a work environment. Some companies go as far as employee termination for repeated violation of security policies. In order to effectively audit a network for security vulnerabilities, one must be familiar with how security can be compromised. In most cases, no. Crackers have many systematic methods of circumventing a networks security structure.
Crackers have many techniques of capturing passwords.
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.