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Computer security, cybersecurity or information technology security (IT security) is the protection of computer systems and networks from information disclosure, theft of or damage to their hardware, software, or electronic data, as well as from the disruption or misdirection of the services they provide.[1]

The field is becoming increasingly significant due to the increased reliance on computer systems, the Internet[2] and wireless network standards such as Bluetooth and Wi-Fi, and due to the growth of "smart" devices, including smartphones, televisions, and the various devices that constitute the "Internet of things". Owing to its complexity, both in terms of politics and technology, cybersecurity is also one of the major challenges in the contemporary world.


Vulnerabilities and attacks

A vulnerability is a weakness in design, implementation, operation, or internal control. Most of the vulnerabilities that have been discovered are documented in the Common Vulnerabilities and Exposures (CVE) database. An exploitable vulnerability is one for which at least one working attack or "exploit" exists.[12] Vulnerabilities can be researched, reverse-engineered, hunted, or exploited using automated tools or customized scripts.[13][14] To secure a computer system, it is important to understand the attacks that can be made against it, and these threats can typically be classified into one of these categories below:

Backdoor

A backdoor in a computer system, a cryptosystem or an algorithm, is any secret method of bypassing normal authentication or security controls. They may exist for many reasons, including by original design or from poor configuration. They may have been added by an authorized party to allow some legitimate access, or by an attacker for malicious reasons; but regardless of the motives for their existence, they create a vulnerability. Backdoors can be very hard to detect, and detection of backdoors are usually discovered by someone who has access to application source code or intimate knowledge of Operating System of the computer.

Denial-of-service attack

Denial of service attacks (DoS) are designed to make a machine or network resource unavailable to its intended users.[15] Attackers can deny service to individual victims, such as by deliberately entering a wrong password enough consecutive times to cause the victim's account to be locked, or they may overload the capabilities of a machine or network and block all users at once. While a network attack from a single IP address can be blocked by adding a new firewall rule, many forms of Distributed denial of service (DDoS) attacks are possible, where the attack comes from numerous points – and defending is much more difficult. Such attacks can originate from the zombie computers of a botnet or from a range of other possible techniques, including reflection and amplification attacks, where innocent systems are fooled into sending traffic to the victim.

Direct-access attacks

An unauthorized user gaining physical access to a computer is most likely able to directly copy data from it. They may also compromise security by making operating system modifications, installing software worms, keyloggers, covert listening devices or using wireless microphone. Even when the system is protected by standard security measures, these may be bypassed by booting another operating system or tool from a CD-ROM or other bootable media. Disk encryption and Trusted Platform Module are designed to prevent these attacks.

Eavesdropping

Eavesdropping is the act of surreptitiously listening to a private computer "conversation" (communication), typically between hosts on a network. For instance, programs such as Carnivore and NarusInSight have been used by the FBI and NSA to eavesdrop on the systems of internet service providers. Even machines that operate as a closed system (i.e., with no contact to the outside world) can be eavesdropped upon via monitoring the faint electromagnetic transmissions generated by the hardware; TEMPEST is a specification by the NSA referring to these attacks.