Hackers delete or alter files. To interfere in a harmful way or to alter improperly. Hackers cause victims to spend time and money checking and resecuring systems after break-in. They also cause them to interrupt service. They think that no harm has been done.
Hackers steal telephone and computer time and share unauthorized access codes and passwords.
Much of the stealing is very low-tech. Social engineering is a term used among crackers for cracking techniques that rely on weaknesses in human beings rather than on software. Dumpster diving is the practice of sifting refuse from an office or technical installation to extract confidential data, especially security compromising information. Hackers crash systems that cause them to malfunction and not work. Intellectual property is the physical expression of ideas contained in books, music, plays, movies, and computer software.