Watch this page
Hacker (computer security)
In the computer security context, a hacker is someone who seeks and exploits weaknesses in a computer system or computer network. Hackers may be motivated by a multitude of reasons, such as profit, protest, challenge, enjoyment,[1] or to evaluate those weaknesses to assist in removing them. The subculture that has evolved around hackers is often referred to as the computer underground and is now a known community.[2] While other uses of the word hacker exist that are related to computer security, such as referring to someone with an advanced understanding of computers and computer networks,[3] they are rarely used in mainstream context.[citation needed] They are subject to the longstanding hacker definition controversy about the term's true meaning. In this controversy, the term hacker is reclaimed by computer programmers who argue that someone who breaks into computers, whether computer criminal (black hats) or computer security expert (white hats),[4] is more appropriately called a cracker instead.[5] Some white hat hackers[who?] claim that they also deserve the title hacker, and that only black hats should be called "crackers".

 

Several subgroups of the computer underground with different attitudes use different terms to demarcate themselves from each other, or try to exclude some specific group with whom they do not agree.

Eric S. Raymond, author of The New Hacker's Dictionary, 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 a wider hacker culture, a view that Raymond has harshly rejected. Instead of a hacker/cracker dichotomy, they emphasize a spectrum of different categories, such as white hat, grey hat, black hat and script kiddie. In contrast to Raymond, they usually reserve the term cracker for more malicious activity.

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".[6] These subgroups may also be defined by the legal status of their activities.[7]

White hat
Main article: White hat
A white hat hacker breaks security for non-malicious reasons, perhaps to test their own security system or while working for a security company which makes security software. The term "white hat" in Internet slang refers to an ethical hacker. This classification also includes individuals who perform penetration tests and vulnerability assessments within a contractual agreement. The EC-Council,[8] also known as the International Council of Electronic Commerce Consultants, is one of those organizations that have developed certifications, courseware, classes, and online training covering the diverse arena of ethical hacking.[7]

Black hat
Main article: Black hat
A "black hat" hacker is a hacker who "violates computer security for little reason beyond maliciousness or for personal gain" (Moore, 2005).[9] 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".[10] Black hat hackers break into secure networks to destroy, modify, or steal data; or to make the network unusable for those who are authorized to use the network. Black hat hackers are also referred to as the "crackers" within the security industry and by modern programmers. Crackers keep the awareness of the vulnerabilities to themselves and do not notify the general public or the manufacturer for patches to be applied. Individual freedom and accessibility is promoted over privacy and security. Once they have gained control over a system, they may apply patches or fixes to the system only to keep their reigning control. Richard Stallman invented the definition to express the maliciousness of a criminal hacker versus a white hat hacker who performs hacking duties to identify places to repair.[11]

Grey hat
Main article: Grey hat
A grey hat hacker lies between a black hat and a white hat hacker. A grey hat hacker may surf the Internet and hack into a computer system for the sole purpose of notifying the administrator that their system has a security defect, for example. They may then offer to correct the defect for a fee.[10] Grey hat hackers sometimes find the defect of a system and publish the facts to the world instead of a group of people. Even though grey hat hackers may not necessarily perform hacking for their personal gain, unauthorized access to a system can be considered illegal and unethical.

Elite hacker
A social status among hackers, elite is used to describe the most skilled. Newly discovered exploits circulate among these hackers. Elite groups such as Masters of Deception conferred a kind of credibility on their members.[12]

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 prearranged plan or set of activities) kiddie (i.e. kid, child—an individual lacking knowledge and experience, immature),[13] usually with little understanding of the underlying concept.

Neophyte
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.[10]

Blue hat
A blue hat hacker is someone outside computer security consulting firms who is used to bug-test a system prior to its launch, looking for exploits so they can be closed. Microsoft also uses the term BlueHat to represent a series of security briefing events.[14][15][16]

Hacktivist
A hacktivist is a hacker who utilizes technology to publicize a social, ideological, religious or political message.

Hacktivism can be divided into two main groups:

Cyberterrorism — Activities involving website defacement or denial-of-service attacks; and,
Freedom of information — Making information that is not public, or is public in non-machine-readable formats, accessible to the public.
Nation state
Intelligence agencies and cyberwarfare operatives of nation states.[17]

Organized criminal gangs
Groups of hackers that carry out organized criminal activities for profit.[17]

Attacks

Main article: Computer security
A typical approach in an attack on Internet-connected system is:

Network enumeration: Discovering information about the intended target.
Vulnerability analysis: Identifying potential ways of attack.
Exploitation: Attempting to compromise the system by employing the vulnerabilities found through the vulnerability analysis.[18]
In order to do so, there are several recurring tools of the trade and techniques used by computer criminals and security experts.

Security exploits
Main article: Exploit (computer security)
A security exploit is a prepared application that takes advantage of a known weakness.[19] Common examples of security exploits are SQL injection, cross-site scripting and cross-site request forgery which abuse security holes that may result from substandard programming practice. Other exploits would be able to be used through File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), PHP, SSH, Telnet and some Web pages. These are very common in Web site and Web domain hacking.

Techniques
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
Hackers may also attempt to find vulnerabilities manually. A common approach is to search for possible vulnerabilities in the code of the computer system then test them, sometimes reverse engineering the software if the code is not provided.
Brute-force attack
Password guessing. This method is very fast when used to check all short passwords, but for longer passwords other methods such as the dictionary attack are used, because of the time a brute-force search takes.
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.
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.
Rootkit
A rootkit is a program that uses low-level, hard-to-detect methods to subvert control of an operating system from its legitimate operators. Rootkits usually obscure their installation and attempt to prevent their removal through a subversion of standard system security. They may include replacements for system binaries, making it virtually impossible for them to be detected by checking process tables.
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.
Hackers who use this technique must have cool personalities, and be familiar with their target's security practices, in order to trick the system administrator into giving them information. In some cases, a help-desk employee with limited security experience will answer the phone and be relatively easy to trick. Another approach is for the hacker to pose as an angry supervisor, and when his/her authority is questioned, threaten to fire the help-desk worker. Social engineering is very effective, because users are the most vulnerable part of an organization. No security devices or programs can keep an organization safe if an employee reveals a password to an unauthorized person.
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.
Helpfulness The opposite of intimidation, helpfulness exploits many people's natural instinct to help others solve problems. Rather than acting angry, the hacker acts distressed and concerned. The help desk is the most vulnerable to this type of social engineering, as (a.) its general purpose is to help people; and (b.) it usually has the authority to change or reset passwords, which is exactly what the hacker wants.
Name-dropping The hacker uses names of authorized users to convince the person who answers the phone that the hacker is a legitimate user him or herself. Some of these names, such as those of webpage owners or company officers, can easily be obtained online. Hackers have also been known to obtain names by examining discarded documents (so-called "dumpster diving").
Technical Using technology is also a way to get information. A hacker can send a fax or email to a legitimate user, seeking a response that contains vital information. The hacker may claim that he or she is involved in law enforcement and needs certain data for an investigation, or for record-keeping purposes.
Trojan horses
A Trojan horse is a program that seems to be doing one thing but is actually doing another. It can be used to set up a back door in a computer system, enabling the intruder to gain access later. (The name refers to the horse from the Trojan War, with the conceptually similar function of deceiving defenders into bringing an intruder into a protected area.)
Computer virus
A virus is a self-replicating program that spreads by inserting copies of itself into other executable code or documents. By doing this, it behaves similarly to a biological virus, which spreads by inserting itself into living cells. While some viruses are harmless or mere hoaxes, most are considered malicious.
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
A keylogger is a tool designed to record ("log") every keystroke on an affected machine for later retrieval, usually to allow the user of this tool to gain access to confidential information typed on the affected machine. Some keyloggers use virus-, trojan-, and rootkit-like methods to conceal themselves. However, some of them are used for legitimate purposes, even to enhance computer security. For example, a business may maintain a keylogger on a computer used at a point of sale to detect evidence of employee fraud.
Tools and Procedures

A thorough examination of hacker tools and procedures may be found in Cengage Learning's E|CSA certification workbook.[20]
Notable intruders and criminal hackers

Main article: List of computer criminals
Notable security hackers

Main article: List of hackers
Jacob Appelbaum is an advocate, security researcher, and developer for the Tor project. He speaks internationally for usage of Tor by human rights groups and others concerned about Internet anonymity and censorship.
Eric Corley (also known as Emmanuel Goldstein) is the longstanding publisher of 2600: The Hacker Quarterly. He is also the founder of the Hackers on Planet Earth (HOPE) conferences. He has been part of the hacker community since the late 1970s.
Ed Cummings (also known as Bernie S) is a longstanding writer for 2600: The Hacker Quarterly. In 1995, he was arrested and charged with possession of technology that could be used for fraudulent purposes, and set legal precedents after being denied both a bail hearing and a speedy trial.