People are prone to taking mental shortcuts. They may know that they shouldn't give out certain information, but the fear of not being nice, the fear of appearing ignorant, the fear of a perceived authority figure - all these are triggers, which can be used by a social engineer to convince a person to override established security procedures.

Penetrating a company's security often starts with the bad guy obtaining some piece of information that seems so innocent, so everyday and unimportant, that most people in the organization don't see any reason why the item should be protected and restricted.

When somebody asks for a favor involving information, if you don't know him or can't verify his identity, just say no.

Kevin Mitnick Quotes