Security hacker

A security hacker is someone who explores methods for breaching defenses and exploiting weaknesses in a computer system or network.[1] Hackers may be motivated by a multitude of reasons, such as profit, protest, information gathering,[2] challenge, recreation,[3] or evaluation of a system weaknesses to assist in formulating defenses against potential hackers. The subculture that has evolved around hackers is often referred to as the “computer underground.”[4]

Longstanding controversy surrounds the meaning of the term “hacker“. In this controversy, computer programmers reclaim the term hacker, arguing that it refers simply to someone with an advanced understanding of computers and computer networks[5] and that cracker is the more appropriate term for those who break into computers, whether computer criminals (black hats) or computer security experts (white hats).[6][7] A 2014 article noted that “… the black-hat meaning still prevails among the general public”.[8]


In computer security, a hacker is someone who focuses on security mechanisms of computer and network systems. While including those who endeavor to strengthen such mechanisms, it is more often used by the mass media and popular culture to refer to those who seek access despite these security measures. That is, the media portrays the ‘hacker’ as a villain. Nevertheless, parts of the subculture see their aim in correcting security problems and use the word in a positive sense. White hat is the name given to ethical computer hackers, who utilize hacking in a helpful way. White hats are becoming a necessary part of the information security field.[9] They operate under a code, which acknowledges that breaking into other people’s computers is bad, but that discovering and exploiting security mechanisms and breaking into computers is still an interesting activity that can be done ethically and legally. Accordingly, the term bears strong connotations that are favorable or pejorative, depending on the context.


In 1980, an article in the August issue of Psychology Today (with commentary by Philip Zimbardo) used the term “hacker” in its title: “The Hacker Papers”. It was an excerpt from a Stanford Bulletin Board discussion on the addictive nature of computer use. In the 1982 film Tron, Kevin Flynn (Jeff Bridges) describes his intentions to break into ENCOM’s computer system, saying “I’ve been doing a little hacking here”. CLU is the software he uses for this. By 1983, hacking in the sense of breaking computer security had already been in use as computer jargon,[10] but there was no public awareness about such activities.[11] However, the release of the film WarGames that year, featuring a computer intrusion into NORAD, raised the public belief that computer security hackers (especially teenagers) could be a threat to national security. This concern became real when, in the same year, a gang of teenage hackers in Milwaukee, Wisconsin, known as The 414s, broke into computer systems throughout the United States and Canada, including those of Los Alamos National Laboratory, Sloan-Kettering Cancer Center and Security Pacific Bank.[12] The case quickly grew media attention,[12][13] and 17-year-old Neal Patrick emerged as the spokesman for the gang, including a cover story in Newsweek entitled “Beware: Hackers at play”, with Patrick’s photograph on the cover.[14] The Newsweek article appears to be the first use of the word hacker by the mainstream media in the pejorative sense.

Pressured by media coverage, congressman Dan Glickman called for an investigation and began work on new laws against computer hacking.[15][16]
Neal Patrick testified before the U.S. House of Representatives on September 26, 1983, about the dangers of computer hacking, and six bills concerning computer crime were introduced in the House that year.[16] As a result of these laws against computer criminality, white hat, grey hat and black hat hackers try to distinguish themselves from each other, depending on the legality of their activities. These moral conflicts are expressed in The Mentor‘s “The Hacker Manifesto“, published 1986 in Phrack.

Use of the term hacker meaning computer criminal was also advanced by the title “Stalking the Wily Hacker”, an article by Clifford Stoll in the May 1988 issue of the Communications of the ACM. Later that year, the release by Robert Tappan Morris, Jr. of the so-called Morris worm provoked the popular media to spread this usage. The popularity of Stoll’s book The Cuckoo’s Egg, published one year later, further entrenched the term in the public’s consciousness.


Subgroups of the computer underground with different attitudes and motives use different terms to demarcate themselves from each other. These classifications are also used to exclude specific groups with whom they do not agree.



According to Ralph D. Clifford, a cracker or cracking is to “gain unauthorized access to a computer in order to commit another crime such as destroying information contained in that system”.[17] These subgroups may also be defined by the legal status of their activities.[18]

White hat

A white hat hacker breaks security for non-malicious reasons, either to test their own security system, perform penetration tests or vulnerability assessments for a client, or while working for a security company which makes security software. The term is generally synonymous with ethical hacker, and the EC-Council,[19] among others, have developed certifications, courseware, classes, and online training covering the diverse arena of ethical hacking.[18]

Black hat

A black hat hacker is a hacker who “violates computer security for little reason beyond maliciousness or for personal gain” (Moore, 2005).[20] The term was coined by Richard Stallman, to contrast the maliciousness of a criminal hacker versus the spirit of playfulness and exploration in hacker culture, or the ethos of the white hat hacker who performs hacking duties to identify places to repair or as a means of legitimate employment.[21] Black hat hackers form the stereotypical, illegal hacking groups often portrayed in popular culture, and are “the epitome of all that the public fears in a computer criminal”.[22]

Grey hat


Elite hacker


Script kiddie

A script kiddie (also known as a skid or skiddie) is an unskilled hacker who breaks into computer systems by using automated tools written by others (usually by other black hat hackers), hence the term script (i.e. a computer script that automates the hacking) kiddie (i.e. kid, child an individual lacking knowledge and experience, immature),[24] usually with little understanding of the underlying concept.


A neophyte (“newbie“, or “noob”) is someone who is new to hacking or phreaking and has almost no knowledge or experience of the workings of technology and hacking.[22]

Blue hat




Hacktivism can be divided into two main groups:

Nation state

Intelligence agencies and cyberwarfare operatives of nation states.[28]

Organized criminal gangs

Groups of hackers that carry out organized criminal activities for profit.[28] Modern-day computer hackers have been compared to the privateers of by-gone days.[29] These criminals hold computer systems hostage, demanding large payments from victims to restore access to their own computer systems and data.[30] Furthermore, recent ransomware attacks on industries, including energy, food, and transportation, have been blamed on criminal organizations based in or near a state actor – possibly with the country’s knowledge and approval.[31] Cyber theft and ransomware attacks are now the fastest-growing crimes in the United States.[32] Bitcoin and other cryptocurrencies facilitate the extortion of huge ransoms from large companies, hospitals and city governments with little or no chance of being caught.[33]


Hackers can usually be sorted into two types of attacks: mass attacks and targeted attacks.[34] They are sorted into the groups in terms of how they choose their victims and how they act on the attacks.[34]


  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.[35]


Security exploits



Vulnerability scanner
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. (Firewalls defend computers from intruders by limiting access to ports and machines, but they can still be circumvented.)
Finding vulnerabilities
Brute-force attack
Password cracking
Password cracking is the process of recovering passwords from data that has been stored in or transmitted by a computer system. Common approaches include repeatedly trying guesses for the password, trying the most common passwords by hand, and repeatedly trying passwords from a “dictionary”, or a text file with many passwords.[38]
Packet analyzer
A packet analyzer (“packet sniffer”) is an application that captures data packets, which can be used to capture passwords and other data in transit over the network.
Spoofing attack (phishing)
A spoofing attack involves one program, system or website that successfully masquerades as another by falsifying data and is thereby treated as a trusted system by a user or another program – usually to fool programs, systems or users into revealing confidential information, such as user names and passwords.
Social engineering
In the second stage of the targeting process, hackers often use social engineering tactics to get enough information to access the network. They may contact the system administrator and pose as a user who cannot get access to his or her system. This technique is portrayed in the 1995 film Hackers, when protagonist Dade “Zero Cool” Murphy calls a somewhat clueless employee in charge of security at a television network. Posing as an accountant working for the same company, Dade tricks the employee into giving him the phone number of a modem so he can gain access to the company’s computer system.
Social engineering can be broken down into four sub-groups:

  • Intimidation As in the “angry supervisor” technique above, the hacker convinces the person who answers the phone that their job is in danger unless they help them. At this point, many people accept that the hacker is a supervisor and give them the information they seek.
Trojan horses
Computer virus
Computer worm
Like a virus, a worm is also a self-replicating program. It differs from a virus in that (a.) it propagates through computer networks without user intervention; and (b.) does not need to attach itself to an existing program. Nonetheless, many people use the terms “virus” and “worm” interchangeably to describe any self-propagating program.
Keystroke logging
Attack patterns

Tools and Procedures

A thorough examination of hacker tools and procedures may be found in Cengage Learning’s E|CSA certification workbook.[40]

Notable intruders and criminal hackers

Notable security hackers


The computer underground[3] has produced its own specialized slang, such as 1337speak. Writing software and performing other activities to support these views is referred to as hacktivism. Some consider illegal cracking ethically justified for these goals; a common form is website defacement. The computer underground is frequently compared to the Wild West.[50] It is common for hackers to use aliases to conceal their identities.

Hacker groups and conventions


Consequences for malicious hacking


Section Offence Punishment


Maximum imprisonment is one year or a fine of the fourth category.[52]

United States

18 U.S.C. § 1030, more commonly known as the Computer Fraud and Abuse Act, prohibits unauthorized access or damage of “protected computers”. “Protected computers” are defined in 18 U.S.C. § 1030(e)(2) as:


The maximum imprisonment or fine for violations of the Computer Fraud and Abuse Act depends on the severity of the violation and the offender’s history of violations under the Act.

The FBI has demonstrated its ability to recover ransoms paid in cryptocurrency by victims of cybertheft.[53]

Hacking and the media

Hacker magazines

The most notable hacker-oriented print publications are Phrack, Hakin9 and 2600: The Hacker Quarterly. While the information contained in hacker magazines and ezines was often outdated by the time they were published, they enhanced their contributors’ reputations by documenting their successes.[51]

Hackers in fiction

Hackers often show an interest in fictional cyberpunk and cyberculture literature and movies. The adoption of fictional pseudonyms,[54] symbols, values and metaphors from these works is very common.[55]



Non-fiction books

Further reading