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81-477: OpenSSH (also known as OpenBSD Secure Shell ) is a suite of secure networking utilities based on the Secure Shell (SSH) protocol, which provides a secure channel over an unsecured network in a client–server architecture. OpenSSH started as a fork of the free SSH program developed by Tatu Ylönen; later versions of Ylönen's SSH were proprietary software offered by SSH Communications Security . OpenSSH

162-411: A key derivation function , the challenge value and the secret may be combined to generate an unpredictable encryption key for the session. This is particularly effective against a man-in-the-middle attack, because the attacker will not be able to derive the session key from the challenge without knowing the secret, and therefore will not be able to decrypt the data stream. where This particular example

243-587: A big impact on information security in organizations. Cultural concepts can help different segments of the organization work effectively or work against effectiveness toward information security within an organization. Information security culture is the "...totality of patterns of behavior in an organization that contributes to the protection of information of all kinds." Andersson and Reimers (2014) found that employees often do not see themselves as part of their organization's information security effort and often take actions that impede organizational changes. Indeed,

324-476: A colleague, which, when listened to by an attacker, could be exploited. Data transmitted across an "open network" allows an attacker to exploit a vulnerability and intercept it via various methods. Unlike malware , direct-access attacks, or other forms of cyber attacks, eavesdropping attacks are unlikely to negatively affect the performance of networks or devices, making them difficult to notice. In fact, "the attacker does not need to have any ongoing connection to

405-412: A consequence make a Cold boot attack possible, to hardware implementation faults that allow for access or guessing of other values that normally should be inaccessible. In Side-channel attack scenarios, the attacker would gather such information about a system or network to guess its internal state and as a result access the information which is assumed by the victim to be secure. The target information in

486-465: A dedicated sshd user by default to drop privileges and perform privilege separation in accordance with the principle of least privilege , applied throughout the operating system including the Xenocara X server . OpenSSH includes the ability to set up a secured channel through which data sent to local, client-side Unix domain sockets or local, client-side TCP ports may be " forwarded " (sent across

567-445: A feature of modern computers that allows certain devices, such as external hard drives, graphics cards, or network cards, to access the computer's memory directly." Eavesdropping is the act of surreptitiously listening to a private computer conversation (communication), usually between hosts on a network. It typically occurs when a user connects to a network where traffic is not secured or encrypted and sends sensitive business data to

648-831: A generic challenge–response mechanism, which is often used for simple password authentication, but which can also make use of stronger authenticators such as tokens ; and Kerberos / GSSAPI . The server makes use of authentication methods native to the host operating system; this can include using the BSD Authentication system or pluggable authentication modules (PAM) to enable additional authentication through methods such as one-time passwords . However, this occasionally has side effects: when using PAM with OpenSSH, it must be run as root , as root privileges are typically required to operate PAM. OpenSSH versions after 3.7 (16 September 2003) allow PAM to be disabled at run-time, so regular users can run sshd instances. On OpenBSD, OpenSSH uses

729-445: A list of three-letter challenge codes, which the verifier is supposed to choose randomly from, and random three-letter responses to them. For added security, each set of codes is only valid for a particular time period which is ordinarily 24 hours. Another basic challenge-response technique works as follows. Bob is controlling access to some resource, and Alice is seeking entry. Bob issues the challenge "52w72y". Alice must respond with

810-476: A malicious code inside a particular HTML or web page. HTML files can carry payloads concealed as benign, inert data in order to defeat content filters . These payloads can be reconstructed on the other side of the filter. When a target user opens the HTML, the malicious code is activated; the web browser then "decodes" the script, which then unleashes the malware onto the target's device. Employee behavior can have

891-439: A new class of multi-vector, polymorphic cyber threats combine several types of attacks and change form to avoid cybersecurity controls as they spread. Multi-vector polymorphic attacks, as the name describes, are both multi-vectored and polymorphic. Firstly, they are a singular attack that involves multiple methods of attack. In this sense, they are “multi-vectored (i.e. the attack can use multiple means of propagation such as via

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972-434: A previous correct response (even if it is not obfuscated by the means of communication) does not allow an adversary to determine the current correct response. Challenge-response protocols are also used in non-cryptographic applications. CAPTCHAs , for example, are meant to allow websites and applications to determine whether an interaction was performed by a genuine user rather than a web scraper or bot . In early CAPTCHAs,

1053-574: A remote attacker to cause OpenSSH to execute arbitrary code and gain full root access. It was inadvertently introduced in prior OpenSSH version 8.5p1 in October 2020, and was patched following version 9.8/9.8p1. In February 2001, Tatu Ylönen, chairman and CTO of SSH Communications Security informed the OpenSSH development mailing list that the company intended to assert its ownership of the "SSH" and "Secure Shell" trademarks , and sought to change references to

1134-450: A remote host, and other protocols, such as HTTP and VNC , may be forwarded easily. Tunneling a TCP- encapsulating payload (such as PPP ) over a TCP-based connection (such as SSH's port forwarding ) is known as "TCP-over-TCP", and doing so can induce a dramatic loss in transmission performance due to the TCP meltdown problem , which is why virtual private network software may instead use for

1215-451: A separate machine filtering network traffic. Firewalls are common amongst machines that are permanently connected to the Internet. Some organizations are turning to big data platforms, such as Apache Hadoop , to extend data accessibility and machine learning to detect advanced persistent threats . Challenge%E2%80%93response The simplest example of a challenge-response protocol

1296-458: A serious supply chain attack on XZ Utils has been reported, targeting indirectly the OpenSSH server (sshd) running on Linux. The OpenSSH code is not directly concerned, the backdoor is caused by the dependencies on liblzma via libsystemd applied by a tierce patch, applied by various Linux distributions. On July 1, 2024, the RegreSSHion security vulnerability was disclosed, which could enable

1377-601: A side channel can be challenging to detect due to its low amplitude when combined with other signals Social engineering , in the context of computer security, aims to convince a user to disclose secrets such as passwords, card numbers, etc. or grant physical access by, for example, impersonating a senior executive, bank, a contractor, or a customer. This generally involves exploiting people's trust, and relying on their cognitive biases . A common scam involves emails sent to accounting and finance department personnel, impersonating their CEO and urgently requesting some action. One of

1458-705: A standard computer user may be able to exploit a vulnerability in the system to gain access to restricted data; or even become root and have full unrestricted access to a system. The severity of attacks can range from attacks simply sending an unsolicited email to a ransomware attack on large amounts of data. Privilege escalation usually starts with social engineering techniques, often phishing . Privilege escalation can be separated into two strategies, horizontal and vertical privilege escalation: Any computational system affects its environment in some form. This effect it has on its environment can range from electromagnetic radiation, to residual effect on RAM cells which as

1539-410: A strong cryptographically secure pseudorandom number generator and cryptographic hash function can generate challenges that are highly unlikely to occur more than once. It is sometimes important not to use time-based nonces, as these can weaken servers in different time zones and servers with inaccurate clocks. It can also be important to use time-based nonces and synchronized clocks if the application

1620-699: A success probability of 2. The vulnerability was related to the CBC encryption mode. The AES CTR mode and arcfour ciphers are not vulnerable to this attack. A local privilege escalation vulnerability existed in OpenSSH 6.8 to 6.9 ( CVE - 2015-6565 ) due to world-writable (622) TTY devices, which was believed to be a denial of service vulnerability. With the use of the TIOCSTI ioctl , it was possible for authenticated users to inject characters into other users terminals and execute arbitrary commands on Linux. Malicious or compromised OpenSSH servers could read sensitive information on

1701-485: A way of filtering network data between a host or a network and another network, such as the Internet . They can be implemented as software running on the machine, hooking into the network stack (or, in the case of most UNIX -based operating systems such as Linux , built into the operating system kernel ) to provide real-time filtering and blocking. Another implementation is a so-called physical firewall , which consists of

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1782-447: 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 a large number of points. In this case, defending against these attacks

1863-419: Is password authentication, where the challenge is asking for the password and the valid response is the correct password. An adversary who can eavesdrop on a password authentication can authenticate themselves by reusing the intercepted password. One solution is to issue multiple passwords, each of them marked with an identifier. The verifier can then present an identifier, and the prover must respond with

1944-493: Is also used for other OpenBSD projects such as OpenNTPD . The OpenSSH suite includes the following command-line utilities and daemons : The OpenSSH server can authenticate users using the standard methods supported by the SSH protocol: with a password; public-key authentication, using per-user keys; host-based authentication, which is a secure version of rlogin 's host trust relationships using public keys; keyboard-interactive,

2025-462: Is available as a package in other systems. OpenBSD Secure Shell was created by OpenBSD developers as an alternative to the original SSH software by Tatu Ylönen, which is now proprietary software . Although source code is available for the original SSH, various restrictions are imposed on its use and distribution. OpenSSH was created as a fork of Björn Grönvall's OSSH that itself was a fork of Tatu Ylönen's original free SSH 1.2.12 release, which

2106-759: Is further amplified by the growth of smart devices , including smartphones , televisions , and the various devices that constitute the Internet of things (IoT). Cybersecurity has emerged as one of the most significant new challenges facing the contemporary world, due to both the complexity of information systems and the societies they support. Security is particularly crucial for systems that govern large-scale systems with far-reaching physical effects, such as power distribution , elections , and finance . Although many aspects of computer security involve digital security, such as electronic passwords and encryption , physical security measures such as metal locks are still used to prevent unauthorized tampering. IT security

2187-500: Is itself forwarded back to the client-side in the same manner; this is known as an " SSH tunnel ", and it can be used to multiplex additional TCP connections over a single SSH connection since 2004, to conceal connections, to encrypt protocols that are otherwise unsecured, and to circumvent firewalls by sending/receiving all manner of data through one port that is allowed by the firewall. For example, an X Window System tunnel may be created automatically when using OpenSSH to connect to

2268-471: Is much more difficult. Such attacks can originate from the zombie computers of a botnet or from a range of other possible techniques, including distributed reflective denial-of-service (DRDoS), where innocent systems are fooled into sending traffic to the victim. With such attacks, the amplification factor makes the attack easier for the attacker because they have to use little bandwidth themselves. To understand why attackers may carry out these attacks, see

2349-508: Is not a perfect subset of information security , therefore does not completely align into the security convergence schema. A vulnerability refers to a flaw in the structure, execution, functioning, or internal oversight of a computer or system that compromises its security. Most of the vulnerabilities that have been discovered are documented in the Common Vulnerabilities and Exposures (CVE) database. An exploitable vulnerability

2430-449: Is not stored, and it is very difficult to determine a password that matches a given hash. However, this presents a problem for many (but not all) challenge-response algorithms, which require both the client and the server to have a shared secret. Since the password itself is not stored, a challenge-response algorithm will usually have to use the hash of the password as the secret instead of the password itself. In this case, an intruder can use

2511-439: Is one for which at least one working attack or exploit exists. Actors maliciously seeking vulnerabilities are known as threats . Vulnerabilities can be researched, reverse-engineered, hunted, or exploited using automated tools or customized scripts. Various people or parties are vulnerable to cyber attacks; however, different groups are likely to experience different types of attacks more than others. In April 2023,

OpenSSH - Misplaced Pages Continue

2592-468: Is possible with ordinary port forwarding. Beginning with version 4.3, OpenSSH implements an OSI layer 2/3 tun -based VPN . This is the most flexible of OpenSSH's tunnelling capabilities, allowing applications to transparently access remote network resources without modifications to make use of SOCKS. OpenSSH supports the following public key types: Before version 5.2 of OpenSSH, it was possible for an attacker to recover up to 14 bits of plaintext with

2673-494: 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 the Trusted Platform Module standard are designed to prevent these attacks. Direct service attackers are related in concept to direct memory attacks which allow an attacker to gain direct access to a computer's memory. The attacks "take advantage of

2754-425: Is spear-phishing which leverages personal or organization-specific details to make the attacker appear like a trusted source. Spear-phishing attacks target specific individuals, rather than the broad net cast by phishing attempts. Privilege escalation describes a situation where an attacker with some level of restricted access is able to, without authorization, elevate their privileges or access level. For example,

2835-424: Is the protection of computer software , systems and networks from threats that can lead to unauthorized information disclosure, theft or damage to hardware , software , or data , as well as from the disruption or misdirection of the services they provide. The significance of the field stems from the expanded reliance on computer systems , the Internet , and wireless network standards . Its importance

2916-418: Is vulnerable to a reflection attack . To avoid storage of passwords, some operating systems (e.g. Unix -type) store a hash of the password rather than storing the password itself. During authentication, the system need only verify that the hash of the password entered matches the hash stored in the password database. This makes it more difficult for an intruder to get the passwords, since the password itself

2997-459: Is vulnerable to a delayed message attack. This attack occurs where an attacker copies a transmission whilst blocking it from reaching the destination, allowing them to replay the captured transmission after a delay of their choosing. This is easily accomplished on wireless channels. The time-based nonce can be used to limit the attacker to resending the message but restricted by an expiry time of perhaps less than one second, likely having no effect upon

3078-482: The USPTO trademark database, many online pundits opined that the term "ssh" was not trademarked, merely the logo using the lower case letters "ssh". In addition, the six years between the company's creation and the time when it began to defend its trademark, and that only OpenSSH was receiving threats of legal repercussions, weighed against the trademark's validity. Both developers of OpenSSH and Ylönen himself were members of

3159-642: The United Kingdom Department for Science, Innovation & Technology released a report on cyber attacks over the last 12 months. They surveyed 2,263 UK businesses, 1,174 UK registered charities, and 554 education institutions. The research found that "32% of businesses and 24% of charities overall recall any breaches or attacks from the last 12 months." These figures were much higher for "medium businesses (59%), large businesses (69%), and high-income charities with £500,000 or more in annual income (56%)." Yet, although medium or large businesses are more often

3240-436: The "practice of designing computer systems to achieve security goals." These goals have overlap with the principles of "security by design" explored above, including to "make initial compromise of the system difficult," and to "limit the impact of any compromise." In practice, the role of a security architect would be to ensure the structure of a system reinforces the security of the system, and that new changes are safe and meet

3321-407: The 'attacker motivation' section. A direct-access attack is when an unauthorized user (an attacker) gains physical access to a computer, most likely to directly copy data from it or steal information. Attackers may also compromise security by making operating system modifications, installing software worms , keyloggers , covert listening devices or using wireless microphones. Even when the system

OpenSSH - Misplaced Pages Continue

3402-519: The IETF working group developing the new standard; after several meetings this group denied Ylönen's request to rename the protocol, citing concerns that it would set a bad precedent for other trademark claims against the IETF. The participants argued that both "Secure Shell" and "SSH" were generic terms and could not be trademarks. Computer security Computer security (also cybersecurity , digital security , or information technology (IT) security )

3483-526: The OpenBSD operating system . Rather than including changes for other operating systems directly into OpenSSH, a separate portability infrastructure is maintained by the OpenSSH Portability Team, and "portable releases" are made periodically. This infrastructure is substantial, partly because OpenSSH is required to perform authentication , a capability that has many varying implementations. This model

3564-508: The Verizon Data Breach Investigations Report 2020, which examined 3,950 security breaches, discovered 30% of cybersecurity incidents involved internal actors within a company. Research shows information security culture needs to be improved continuously. In "Information Security Culture from Analysis to Change", authors commented, "It's a never-ending process, a cycle of evaluation and change or maintenance." To manage

3645-558: The Web, email and applications." However, they are also multi-staged, meaning that “they can infiltrate networks and move laterally inside the network.” The attacks can be polymorphic, meaning that the cyberattacks used such as viruses, worms or trojans “constantly change (“morph”) making it nearly impossible to detect them using signature-based defences.” Phishing is the attempt of acquiring sensitive information such as usernames, passwords, and credit card details directly from users by deceiving

3726-491: The addition of ciphers (e.g., ChaCha20-Poly1305 in 6.5 of January 2014), cutting the dependency on OpenSSL (6.7, October 2014) and an extension to facilitate public-key discovery and rotation for trusted hosts (for transition from DSA to Ed25519 public host keys, version 6.8 of March 2015). On 19 October 2015, Microsoft announced that OpenSSH will be natively supported on Microsoft Windows and accessible through PowerShell , releasing an early implementation and making

3807-439: The application and so mitigating the attack. Mutual authentication is performed using a challenge-response handshake in both directions; the server ensures that the client knows the secret, and the client also ensures that the server knows the secret, which protects against a rogue server impersonating the real server. Challenge-response authentication can help solve the problem of exchanging session keys for encryption. Using

3888-505: The best form of encryption possible for wireless networks is best practice, as well as using HTTPS instead of an unencrypted HTTP . Programs such as Carnivore and NarusInSight have been used by the Federal Bureau of Investigation (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 with the outside world) can be eavesdropped upon by monitoring

3969-433: The challenge is an encrypted integer N , while the response is the encrypted integer N + 1 , proving that the other end was able to decrypt the integer N . A hash function can also be applied to a password and a random challenge value to create a response value. Another variation uses a probabilistic model to provide randomized challenges conditioned on model input. Such encrypted or hashed exchanges do not directly reveal

4050-413: The challenge sent to the user was a distorted image of some text, and the user responded by transcribing the text. The distortion was designed to make automated optical character recognition (OCR) difficult and prevent a computer program from passing as a human. Non-cryptographic authentication was generally adequate in the days before the Internet , when the user could be sure that the system asking for

4131-480: The clear over the communication channel. One way this is done involves using the password as the encryption key to transmit some randomly generated information as the challenge , whereupon the other end must return as its response a similarly encrypted value which is some predetermined function of the originally offered information, thus proving that it was able to decrypt the challenge. For instance, in Kerberos ,

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4212-626: The client such as private login keys for other systems, using a vulnerability that relies on the undocumented connection-resuming feature of the OpenSSH client, which is called roaming, enabled by default on the client, but not supported on the OpenSSH server. This applies to versions 5.4 (released on 8 March 2010) to 7.1 of the OpenSSH client, and was fixed in OpenSSH ;7.1p2, released on 14 January 2016. CVE numbers associated to this vulnerability are CVE - 2016-0777 (information leak) and CVE - 2016-0778 (buffer overflow). On March 29, 2024,

4293-561: The code publicly available. OpenSSH-based client and server programs have been included in Windows 10 since version 1803. The SSH client and key agent are enabled and available by default, and the SSH server is an optional Feature-on-Demand. In October 2019 protection for private keys at rest in RAM against speculation and memory side-channel attacks were added in OpenSSH 8.1. OpenSSH is developed as part of

4374-489: The correct password for that identifier. Assuming that the passwords are chosen independently, an adversary who intercepts one challenge-response message pair has no clues to help with a different challenge at a different time. For example, when other communications security methods are unavailable, the U.S. military uses the AKAC-1553 TRIAD numeral cipher to authenticate and encrypt some communications. TRIAD includes

4455-416: The entire computer." Backdoors can be very hard to detect and are usually discovered by someone who has access to the application source code or intimate knowledge of the operating system of the computer. Denial-of-service attacks (DoS) are designed to make a machine or network resource unavailable to its intended users. Attackers can deny service to individual victims, such as by deliberately entering

4536-409: The exchanged data and retransmits it at a later time to fool one end into thinking it has authenticated a new connection attempt from the other. Authentication protocols usually employ a cryptographic nonce as the challenge to ensure that every challenge-response sequence is unique. This protects against Eavesdropping with a subsequent replay attack . If it is impractical to implement a true nonce,

4617-465: The faint electromagnetic transmissions generated by the hardware. TEMPEST is a specification by the NSA referring to these attacks. Malicious software ( malware ) is any software code or computer program "intentionally written to harm a computer system or its users." Once present on a computer, it can leak sensitive details such as personal information, business information and passwords, can give control of

4698-457: The following sections: Security by design, or alternately secure by design, means that the software has been designed from the ground up to be secure. In this case, security is considered a main feature. The UK government's National Cyber Security Centre separates secure cyber design principles into five sections: These design principles of security by design can include some of the following techniques: Security architecture can be defined as

4779-490: The information security culture, five steps should be taken: pre-evaluation, strategic planning, operative planning, implementation, and post-evaluation. In computer security, a countermeasure is an action, device, procedure or technique that reduces a threat, a vulnerability, or an attack by eliminating or preventing it, by minimizing the harm it can cause, or by discovering and reporting it so that corrective action can be taken. Some common countermeasures are listed in

4860-449: The life-threatening risk of spoofing in the healthcare industry. Tampering describes a malicious modification or alteration of data. It is an intentional but unauthorized act resulting in the modification of a system, components of systems, its intended behavior, or data. So-called Evil Maid attacks and security services planting of surveillance capability into routers are examples. HTML smuggling allows an attacker to "smuggle"

4941-515: The main techniques of social engineering are phishing attacks. In early 2016, the FBI reported that such business email compromise (BEC) scams had cost US businesses more than $ 2 billion in about two years. In May 2016, the Milwaukee Bucks NBA team was the victim of this type of cyber scam with a perpetrator impersonating the team's president Peter Feigin , resulting in the handover of all

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5022-473: The nature of backdoors, they are of greater concern to companies and databases as opposed to individuals. Backdoors may be added by an authorized party to allow some legitimate access or by an attacker for malicious reasons. Criminals often use malware to install backdoors, giving them remote administrative access to a system. Once they have access, cybercriminals can "modify files, steal personal information, install unwanted software, and even take control of

5103-413: The one string of characters which "fits" the challenge Bob issued. The "fit" is determined by an algorithm defined in advance, and known by both Bob and Alice. The correct response might be as simple as "63x83z", with the algorithm changing each character of the challenge using a Caesar cipher . In reality, the algorithm would be much more complex. Bob issues a different challenge each time, and thus knowing

5184-560: The openness of the Internet. These strategies mostly include phishing , ransomware , water holing and scanning. 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 the following categories: A backdoor in a computer system, a cryptosystem , or an algorithm is any secret method of bypassing normal authentication or security controls. These weaknesses may exist for many reasons, including original design or poor configuration. Due to

5265-410: The password to an eavesdropper. However, they may supply enough information to allow an eavesdropper to deduce what the password is, using a dictionary attack or brute-force attack . The use of information which is randomly generated on each exchange (and where the response is different from the challenge) guards against the possibility of a replay attack , where a malicious intermediary simply records

5346-427: The password was really the system they were trying to access, and that nobody was likely to be eavesdropping on the communication channel . To address the insecure channel problem, a more sophisticated approach is necessary. Many cryptographic solutions involve two-way authentication; both the user and the system must verify that they know the shared secret (the password), without the secret ever being transmitted in

5427-423: The protocol as an open standard. Without marking these within the proposal as registered trademarks, Ylönen ran the risk of relinquishing all exclusive rights to the name as a means of describing the protocol. Improper use of a trademark, or allowing others to use a trademark incorrectly, results in the trademark becoming a generic term, like Kleenex or Aspirin , which opens the mark to use by others. After study of

5508-406: The protocol to "SecSH" or "secsh", in order to maintain control of the "SSH" name. He proposed that OpenSSH change its name in order to avoid a lawsuit, a suggestion that developers resisted. OpenSSH developer Damien Miller replied urging Ylönen to reconsider, arguing that "SSH" had long since been a generic trademark . At the time, "SSH", "Secure Shell" and "ssh" had appeared in documents proposing

5589-428: The real website. Preying on a victim's trust, phishing can be classified as a form of social engineering . Attackers can use creative ways to gain access to real accounts. A common scam is for attackers to send fake electronic invoices to individuals showing that they recently purchased music, apps, or others, and instructing them to click on a link if the purchases were not authorized. A more strategic type of phishing

5670-476: The right foundation to systematically address business, IT and security concerns in an organization. A state of computer security is the conceptual ideal, attained by the use of three processes: threat prevention, detection, and response. These processes are based on various policies and system components, which include the following: Today, computer security consists mainly of preventive measures, like firewalls or an exit procedure . A firewall can be defined as

5751-429: The secured channel) for routing on the server side; when this forwarding is set up, the server is instructed to send that forwarded data to some socket or TCP host/port (the host could be the server itself, "localhost"; or, the host may be some other computer, so that it appears to the other computer that the server is the originator of the data). The forwarding of data is bidirectional, meaning that any return communication

5832-432: The security requirements of the organization. Similarly, Techopedia defines security architecture as "a unified security design that addresses the necessities and potential risks involved in a certain scenario or environment. It also specifies when and where to apply security controls. The design process is generally reproducible." The key attributes of security architecture are: Practicing security architecture provides

5913-504: The server side, where the OpenSSH server similarly "unwraps" the payload in order to "wrap" it up again for routing to its final destination. In addition, some third-party software includes support for tunnelling over SSH. These include DistCC , CVS , rsync , and Fetchmail . On some operating systems, remote file systems can be mounted over SSH using tools such as sshfs (using FUSE ). An ad hoc SOCKS proxy server may be created using OpenSSH. This allows more flexible proxying than

5994-448: The software at all. The attacker can insert the software onto a compromised device, perhaps by direct insertion or perhaps by a virus or other malware, and then come back some time later to retrieve any data that is found or trigger the software to send the data at some determined time." Using a virtual private network (VPN), which encrypts data between two points, is one of the most common forms of protection against eavesdropping. Using

6075-672: The system to the attacker, and can corrupt or delete data permanently. Another type of malware is ransomware , which is when "malware installs itself onto a victim's machine, encrypts their files, and then turns around and demands a ransom (usually in Bitcoin ) to return that data to the user." Types of malware include some of the following: Man-in-the-middle attacks (MITM) involve a malicious attacker trying to intercept, surveil or modify communications between two parties by spoofing one or both party's identities and injecting themselves in-between. Types of MITM attacks include: Surfacing in 2017,

6156-428: The team's employees' 2015 W-2 tax forms. Spoofing is an act of pretending to be a valid entity through the falsification of data (such as an IP address or username), in order to gain access to information or resources that one is otherwise unauthorized to obtain. Spoofing is closely related to phishing . There are several types of spoofing, including: In 2018, the cybersecurity firm Trellix published research on

6237-423: The tunnel connection a protocol simpler than TCP. However, this is often not a problem when using OpenSSH's port forwarding, because many use cases do not entail TCP-over-TCP tunneling; the meltdown is avoided because the OpenSSH client processes the local, client-side TCP connection in order to get to the actual payload that is being sent, and then sends that payload directly through the tunnel's own TCP connection to

6318-427: The users. Phishing is typically carried out by email spoofing , instant messaging , text message , or on a phone call. They often direct users to enter details at a fake website whose look and feel are almost identical to the legitimate one. The fake website often asks for personal information, such as login details and passwords. This information can then be used to gain access to the individual's real account on

6399-616: The victims, since larger companies have generally improved their security over the last decade, small and midsize businesses (SMBs) have also become increasingly vulnerable as they often "do not have advanced tools to defend the business." SMBs are most likely to be affected by malware, ransomware, phishing, man-in-the-middle attacks , and Denial-of Service (DoS) Attacks. Normal internet users are most likely to be affected by untargeted cyberattacks. These are where attackers indiscriminately target as many devices, services, or users as possible. They do this using techniques that take advantage of

6480-454: Was first released in 1999 and is currently developed as part of the OpenBSD operating system . OpenSSH is not a single computer program, but rather a suite of programs that serve as alternatives to unencrypted protocols like Telnet and FTP . OpenSSH is integrated into several operating systems, namely Microsoft Windows , macOS and most Linux operating systems, while the portable version

6561-500: Was the last one having a license suitable for forking. The OpenSSH developers claim that their application is more secure than the original, due to their policy of producing clean and audited code and because it is released under the BSD license , the open-source license to which the word open in the name refers. OpenSSH first appeared in OpenBSD 2.6. The first portable release was made in October 1999. Developments since then have included

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