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Definition: transitive and intransitive verb cut something using repeated blows: to cut or chop something by striking it with short repeated blows using a sharp tool such as a knife or an ax. As a transitive verb means cut way through obstruction: to cut a path or way through an obstruction, e.g. undergrowth. It means also chop something off or into parts: to cut, shape, or divide something roughly or carelessly. In computer science, hack verb means gain unauthorized access to computer data: to use a computer or other technological device or system in order to gain unauthorized access to data held by another person or organization; a transitive verb meaning cope with something: to succeed at or endure something. (Encarta Dictionary).
Hacking developed alongside "Phone Phreaking", a term referred to exploration of the phone network without authorization, and there has often been overlap between both technology and participants. Bruce Sterling traces part of the roots of the computer underground to the Yippies, a 1960s counterculture movement which published the Technological Assistance Program (TAP) newsletter. . Other sources of early 70s hacker culture can be traced towards more beneficial forms of hacking, including MIT labs or the homebrew club, which later resulted in such things as early personal computers or the open source movement.
Artifacts and customs
The computer underground is heavily dependent on technology. It has produced its own slang and various forms of unusual alphabet use, for example 1337speak. Writing programs and performing other activities to support these views is referred to as hacktivism. Some go as far as seeing illegal cracking ethically justified for this goal; the most common form is website defacement. The computer underground is frequently compared to the Wild West. It is common among hackers to use aliases for the purpose of concealing identity, rather than revealing their real names.
The computer underground is supported by regular real-world gatherings called hacker conventions or "hacker cons". These have drawn more people every year including SummerCon (Summer), DEF CON, HoHoCon (Christmas), and H.O.P.E.. They have helped expand the definition and solidify the importance of the computer underground.
Several subgroups of the computer underground with different attitudes and aims use different terms to demarcate themselves from each other, or try to exclude some specific group with which they do not agree. Eric S. Raymond advocates that members of the computer underground should be called crackers. Yet, those people see themselves as hackers and even try to include the views of Raymond in what they see as one wider hacker culture, a view harshly rejected by Raymond himself. Instead of a hacker – cracker dichotomy, they give more emphasis to a spectrum of different categories, such as white hat (ethical hacking), grey hat, black hat and script kiddie. In contrast to Raymond, they usually reserve the term cracker to refer to black hat hackers, or more generally hackers with unlawful intentions.
A white hat hacker breaks security for non-malicious reasons, for instance testing their own security system. This type of hacker enjoys learning and working with computer systems, and consequently gains a deeper understanding of the subject. Such people normally go on to use their hacking skills in legitimate ways, such as becoming security consultants. The word 'hacker' originally included people like this, although a hacker may not be someone into security.
A grey hat hacker is a hacker of ambiguous ethics and/or borderline legality, often frankly admitted.
A black hat hacker is someone who breaks computer security without authorization or uses technology (usually a computer, phone system or network) for vandalism, credit card fraud, identity theft, piracy, or other types of illegal activity.
A script kiddie is a non-expert who breaks into computer systems by using pre-packaged automated tools written by others, usually with little understanding. These are the outcasts of the hacker community.
A hacktivist is a hacker who utilizes technology to announce a social, ideological, religious, or political message. In general, most hactivism involves website defacement or denial-of-service attacks. In more extreme cases, hactivism is used as tool for Cyberterrorism.
A typical approach in an attack on Internet-connected system is:
1. Network enumeration: Discovering information about the intended target.
2. Vulnerability analysis: Identifying potential ways of attack.
3. Exploitation: Attempting to compromise the system by employing the vulnerabilities found through the vulnerability analysis. 
In order to do so, there are several recurring tools of the trade and techniques used by computer criminals and security experts.
A security exploit is a prepared application that takes advantage of a known weakness. A common example of a security exploit is a fail programming attempt that would allow an SQL injection. Other exploits would be able to be used through FTP, HTTP, PHP, SSH, Telnet and some web-pages. These are very common in website/domain hacking.
A vulnerability scanner is a tool used to quickly check computers on a network for known weaknesses. Hackers also commonly use port scanners. These check to see which ports on a specified computer are "open" or available to access the computer, and sometimes will detect what program or service is listening on that port, and its version number. (Note that firewalls defend computers from intruders by limiting access to ports/machines both inbound and outbound, but can still be circumvented.)
A packet sniffer is an application that captures data packets, which can be used to capture passwords and other data in transit over the network.
A spoofing attack involves one program, system, or website successfully masquerading as another by falsifying data and thereby being treated as a trusted system by a user or another program. The purpose of this is usually to fool programs, systems, or users into revealing confidential information, such as user names and passwords, to the attacker.
A rootkit is designed to conceal the compromise of a computer's security, and can represent any of a set of programs which work to subvert control of an operating system from its legitimate operators. Usually, a rootkit will obscure its installation and attempt to prevent its removal through a subversion of standard system security. Rootkits may include replacements for system binaries so that it becomes impossible for the legitimate user to detect the presence of the intruder on the system by looking at process tables.
Social Engineering is the art of getting persons to reveal sensitive information about a system. This is usually done by impersonating someone or by convincing people to believe you have permissions to obtain such information.
A Trojan horse is a program which seems to be doing one thing, but is actually doing another. A trojan horse can be used to set up a back door in a computer system such that the intruder can gain access later. (The name refers to the horse from the Trojan War, with conceptually similar function of deceiving defenders into bringing an intruder inside.)
A virus is a self-replicating program that spreads by inserting copies of itself into other executable code or documents. Thus, a computer virus behaves in a way similar to a biological virus, which spreads by inserting itself into living cells.
Like a virus, a worm is also a self-replicating program. A worm differs from a virus in that it propagates through computer networks without user intervention. Unlike a virus, it does not need to attach itself to an existing program. Many people conflate the terms "virus" and "worm", using them both to describe any self-propagating program.
A keylogger is a tool designed to record ('log') every keystroke on an affected machine for later retrieval. Its purpose is usually to allow the user of this tool to gain access to confidential information typed on the affected machine, such as a user's password or other private data. Often uses virus-, trojan-, and rootkit-like methods to remain active and hidden.
Notable Security Hackers
Kevin Mitnick is a computer security consultant and author, formerly the most wanted computer criminal in United States history.
Eric Gorden Corley
Eric Corley (also known as Emmanuel Goldstein) is the long standing publisher of 2600: The Hacker Quarterly. He is also the founder of the H.O.P.E. conferences. He has been part of the hacker community since the late '70s.
Gordon Lyon, known by the handle Fyodor, authored the Nmap Security Scanner as well as many network security books and web sites. He is a founding member of the Honeynet Project and Vice President of Computer Professionals for Social Responsibility.
Solar Designer is the pseudonym of the founder of the Openwall Project.
Michal Zalewski (lcamtuf) is a prominent security researcher.
Gary McKinnon is a British hacker facing extradition to the United States to face charges of perpetrating what has been described as the "biggest military computer hack of all time."
The most notable hacker-oriented magazine publications are Phrack, Hakin9 and 2600: The Hacker Quarterly. While the information contained in hacker magazines and ezines was often outdated, they improved the reputations of those who contributed by documenting their successes.
Taylor, Paul A. (1999). Hackers. Routledge. ISBN 9780415180726.
1. a b Sterling, Bruce. "Part 2(d)". The Hacker Crackdown. McLean, Virginia: IndyPublish.com. p. 61. ISBN 1-4043-0641-2.
2. Blomquist, Brian (May 29, 1999). "FBI's Web Site Socked as Hackers Target Feds". New York Post. Retrieved on October 21, 2008.
3. TAP Magazine Archive. http://servv89pn0aj.sn.sourcedns.com/~gbpprorg/2600/TAP/
4. Tim Jordan, Paul A. Taylor (2004). Hacktivism and Cyberwars. Routledge. pp. 133–134. ISBN 9780415260039. "Wild West imagery has permeated discussions of cybercultures."
5. Hacking approach
6. Boyd, Clark (30 July 2008). "Profile: Gary McKinnon". BBC News. http://news.bbc.co.uk/2/hi/technology/4715612.stm. Retrieved 2008-11-15.
7. Thomas, Douglas. Hacker Culture. University of Minnesota Press. p. 90. ISBN 9780816633463.
8. Staples, Brent (May 11, 2003). "A Prince of Cyberpunk Fiction Moves Into the Mainstream". http://www.nytimes.com/2003/05/11/opinion/11SUN3.html?ex=136... Retrieved 2008-08-30. "Mr. Gibson's novels and short stories are worshiped by hackers"