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107-416: Computer security (also cybersecurity , digital security , or information technology (IT) security ) 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

214-480: A computer . Software also includes design documents and specifications. The history of software is closely tied to the development of digital computers in the mid-20th century. Early programs were written in the machine language specific to the hardware. The introduction of high-level programming languages in 1958 allowed for more human-readable instructions, making software development easier and more portable across different computer architectures . Software in

321-527: A provider and accessed over the Internet . The process of developing software involves several stages. The stages include software design , programming , testing , release , and maintenance . Software quality assurance and security are critical aspects of software development, as bugs and security vulnerabilities can lead to system failures and security breaches. Additionally, legal issues such as software licenses and intellectual property rights play

428-509: A vulnerability . Software patches are often released to fix identified vulnerabilities, but those that remain unknown ( zero days ) as well as those that have not been patched are still liable for exploitation. Vulnerabilities vary in their ability to be exploited by malicious actors, and the actual risk is dependent on the nature of the vulnerability as well as the value of the surrounding system. Although some vulnerabilities can only be used for denial of service attacks that compromise

535-520: A web application —had become the primary method that companies deliver applications. Software companies aim to deliver a high-quality product on time and under budget. A challenge is that software development effort estimation is often inaccurate. Software development begins by conceiving the project, evaluating its feasibility, analyzing the business requirements, and making a software design . Most software projects speed up their development by reusing or incorporating existing software, either in

642-667: A backdoor was discovered in certain Samsung Android products, like the Galaxy devices. The Samsung proprietary Android versions are fitted with a backdoor that provides remote access to the data stored on the device. In particular, the Samsung Android software that is in charge of handling the communications with the modem, using the Samsung IPC protocol, implements a class of requests known as remote file server (RFS) commands, that allows

749-585: 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,

856-457: A change request. Frequently, software is released in an incomplete state when the development team runs out of time or funding. Despite testing and quality assurance , virtually all software contains bugs where the system does not work as intended. Post-release software maintenance is necessary to remediate these bugs when they are found and keep the software working as the environment changes over time. New features are often added after

963-486: A code's correct and efficient behavior, its reusability and portability , or the ease of modification. It is usually more cost-effective to build quality into the product from the beginning rather than try to add it later in the development process. Higher quality code will reduce lifetime cost to both suppliers and customers as it is more reliable and easier to maintain . Software failures in safety-critical systems can be very serious including death. By some estimates,

1070-474: 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

1177-554: A combination of the two. The theory of asymmetric backdoors is part of a larger field now called cryptovirology . Notably, NSA inserted a kleptographic backdoor into the Dual EC DRBG standard. There exists an experimental asymmetric backdoor in RSA key generation. This OpenSSL RSA backdoor, designed by Young and Yung, utilizes a twisted pair of elliptic curves, and has been made available. A sophisticated form of black box backdoor

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1284-412: 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

1391-444: A covert backdoor becomes unveiled. Even direct admissions of responsibility must be scrutinized carefully if the confessing party is beholden to other powerful interests. Many computer worms , such as Sobig and Mydoom , install a backdoor on the affected computer (generally a PC on broadband running Microsoft Windows and Microsoft Outlook ). Such backdoors appear to be installed so that spammers can send junk e-mail from

1498-435: A covert rootkit running in the photomask etching equipment could enact this discrepancy unbeknown to the photomask manufacturer, either, and by such means, one backdoor potentially leads to another. In general terms, the long dependency-chains in the modern, highly specialized technological economy and innumerable human-elements process control-points make it difficult to conclusively pinpoint responsibility at such time as

1605-867: A different meaning (see trapdoor function ), and thus the term "backdoor" is now preferred, only after the term trapdoor went out of use. More generally, such security breaches were discussed at length in a RAND Corporation task force report published under DARPA sponsorship by J.P. Anderson and D.J. Edwards in 1970. While initially targeting the computer vision domain, backdoor attacks have expanded to encompass various other domains, including text, audio, ML-based computer-aided design, and ML-based wireless signal classification. Additionally, vulnerabilities in backdoors have been demonstrated in deep generative models , reinforcement learning (e.g., AI GO), and deep graph models. These broad-ranging potential risks have prompted concerns from national security agencies regarding their potentially disastrous consequences. A backdoor in

1712-444: 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

1819-443: A legal regime where liability for software products is significantly curtailed compared to other products. Source code is protected by copyright law that vests the owner with the exclusive right to copy the code. The underlying ideas or algorithms are not protected by copyright law, but are often treated as a trade secret and concealed by such methods as non-disclosure agreements . Software copyright has been recognized since

1926-411: A login system might take the form of a hard coded user and password combination which gives access to the system. An example of this sort of backdoor was used as a plot device in the 1983 film WarGames , in which the architect of the " WOPR " computer system had inserted a hardcoded password-less account which gave the user access to the system, and to undocumented parts of the system (in particular,

2033-473: 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

2140-528: A modified version of the Unix C compiler that would put an invisible backdoor in the Unix login command when it noticed that the login program was being compiled, and would also add this feature undetectably to future compiler versions upon their compilation as well. As the compiler itself was a compiled program, users would be extremely unlikely to notice the machine code instructions that performed these tasks. (Because of

2247-436: 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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2354-468: A number of cloak and dagger considerations that come into play when apportioning responsibility. Covert backdoors sometimes masquerade as inadvertent defects (bugs) for reasons of plausible deniability . In some cases, these might begin life as an actual bug (inadvertent error), which, once discovered are then deliberately left unfixed and undisclosed, whether by a rogue employee for personal advantage, or with C-level executive awareness and oversight. It

2461-416: A paper published in the proceedings of the 1967 AFIPS Conference. They noted a class of active infiltration attacks that use "trapdoor" entry points into the system to bypass security facilities and permit direct access to data. The use of the word trapdoor here clearly coincides with more recent definitions of a backdoor. However, since the advent of public key cryptography the term trapdoor has acquired

2568-406: A part of the standard library and compiles it. After that, every program compiled by that Delphi installation will contain the virus. An attack that propagates by building its own Trojan horse can be especially hard to discover. It resulted in many software vendors releasing infected executables without realizing it, sometimes claiming false positives. After all, the executable was not tampered with,

2675-437: A programming language is run through a compiler or interpreter to execute on the architecture's hardware. Over time, software has become complex, owing to developments in networking , operating systems , and databases . Software can generally be categorized into two main types: The rise of cloud computing has introduced the new software delivery model Software as a Service (SaaS). In SaaS, applications are hosted by

2782-502: A quick web search . Most creative professionals have switched to software-based tools such as computer-aided design , 3D modeling , digital image editing , and computer animation . Almost every complex device is controlled by software. Backdoor (computing) In the United States, the 1994 Communications Assistance for Law Enforcement Act forces internet providers to provide backdoors for government authorities. In 2024,

2889-464: 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 . Computer software Software consists of computer programs that instruct the execution of

2996-599: 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

3103-495: A significant role in the distribution of software products. The first use of the word software is credited to mathematician John Wilder Tukey in 1958. The first programmable computers, which appeared at the end of the 1940s, were programmed in machine language . Machine language is difficult to debug and not portable across different computers. Initially, hardware resources were more expensive than human resources . As programs became complex, programmer productivity became

3210-458: A specific version of the software, downloaded, and run on hardware belonging to the purchaser. The rise of the Internet and cloud computing enabled a new model, software as a service (SaaS), in which the provider hosts the software (usually built on top of rented infrastructure or platforms ) and provides the use of the software to customers, often in exchange for a subscription fee . By 2023, SaaS products—which are usually delivered via

3317-704: 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

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3424-482: A system has been compromised with a backdoor or Trojan horse, such as the Trusting Trust compiler, it is very hard for the "rightful" user to regain control of the system – typically one should rebuild a clean system and transfer data (but not executables) over. However, several practical weaknesses in the Trusting Trust scheme have been suggested. For example, a sufficiently motivated user could painstakingly review

3531-415: A system's availability, others allow the attacker to inject and run their own code (called malware ), without the user being aware of it. To thwart cyberattacks, all software in the system must be designed to withstand and recover from external attack. Despite efforts to ensure security, a significant fraction of computers are infected with malware. Programming languages are the format in which software

3638-416: A variant where the system initialization code is modified to insert a backdoor during booting , as this is complex and poorly understood, and call it an "initialization trapdoor"; this is now known as a boot sector virus . This attack was then actually implemented by Ken Thompson , and popularized in his Turing Award acceptance speech in 1983, "Reflections on Trusting Trust", which points out that trust

3745-497: A video game-like simulation mode and direct interaction with the artificial intelligence ). Although the number of backdoors in systems using proprietary software (software whose source code is not publicly available) is not widely credited, they are nevertheless frequently exposed. Programmers have even succeeded in secretly installing large amounts of benign code as Easter eggs in programs, although such cases may involve official forbearance, if not actual permission. There are

3852-434: 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

3959-447: 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

4066-415: Is a compiler backdoor , where not only is a compiler subverted—to insert a backdoor in some other program, such as a login program—but it is further modified to detect when it is compiling itself and then inserts both the backdoor insertion code (targeting the other program) and the code-modifying self-compilation, like the mechanism through which retroviruses infect their host. This can be done by modifying

4173-456: Is also possible for an entirely above-board corporation's technology base to be covertly and untraceably tainted by external agents (hackers), though this level of sophistication is thought to exist mainly at the level of nation state actors. For example, if a photomask obtained from a photomask supplier differs in a few gates from its photomask specification, a chip manufacturer would be hard-pressed to detect this if otherwise functionally silent;

4280-557: Is much harder to inspect, as it is designed to be machine-readable, not human-readable. These backdoors can be inserted either directly in the on-disk object code, or inserted at some point during compilation, assembly linking, or loading—in the latter case the backdoor never appears on disk, only in memory. Object code backdoors are difficult to detect by inspection of the object code, but are easily detected by simply checking for changes (differences), notably in length or in checksum, and in some cases can be detected or analyzed by disassembling

4387-470: 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

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4494-507: 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

4601-435: 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,

4708-493: 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

4815-431: Is relative, and the only software one can truly trust is code where every step of the bootstrapping has been inspected. This backdoor mechanism is based on the fact that people only review source (human-written) code, and not compiled machine code ( object code ). A program called a compiler is used to create the second from the first, and the compiler is usually trusted to do an honest job. Thompson's paper describes

4922-423: 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,

5029-453: Is written. Since the 1950s, thousands of different programming languages have been invented; some have been in use for decades, while others have fallen into disuse. Some definitions classify machine code —the exact instructions directly implemented by the hardware—and assembly language —a more human-readable alternative to machine code whose statements can be translated one-to-one into machine code—as programming languages. Programs written in

5136-640: 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

5243-438: The high-level programming languages used to create software share a few main characteristics: knowledge of machine code is not necessary to write them, they can be ported to other computer systems, and they are more concise and human-readable than machine code. They must be both human-readable and capable of being translated into unambiguous instructions for computer hardware. The invention of high-level programming languages

5350-437: The revision control system . In this case, a two-line change appeared to check root access permissions of a caller to the sys_wait4 function, but because it used assignment = instead of equality checking == , it actually granted permissions to the system. This difference is easily overlooked, and could even be interpreted as an accidental typographical error, rather than an intentional attack. In January 2014,

5457-434: 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

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5564-406: 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

5671-420: The U.S. government realized that China had been tapping communications in the U.S. using that infrastructure for months, or perhaps longer; China recorded presidential candidate campaign office phone calls —including employees of the then-vice president of the nation– and of the candidates themselves. A backdoor may take the form of a hidden part of a program, a separate program (e.g. Back Orifice may subvert

5778-507: 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

5885-556: 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

5992-423: The attacker who plants it, even if the full implementation of the backdoor becomes public (e.g. via publishing, being discovered and disclosed by reverse engineering , etc.). Also, it is computationally intractable to detect the presence of an asymmetric backdoor under black-box queries. This class of attacks have been termed kleptography ; they can be carried out in software, hardware (for example, smartcards ), or

6099-469: The backdoor operator to perform via modem remote I/O operations on the device hard disk or other storage. As the modem is running Samsung proprietary Android software, it is likely that it offers over-the-air remote control that could then be used to issue the RFS commands and thus to access the file system on the device. Harder to detect backdoors involve modifying object code , rather than source code—object code

6206-400: The backdoor, for example detecting that the subverted binary is being checksummed and returning the expected value, not the actual value. To conceal these further subversions, the tools must also conceal the changes in themselves—for example, a subverted checksummer must also detect if it is checksumming itself (or other subverted tools) and return false values. This leads to extensive changes in

6313-504: 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

6420-399: The bottleneck. The introduction of high-level programming languages in 1958 hid the details of the hardware and expressed the underlying algorithms into the code . Early languages include Fortran , Lisp , and COBOL . There are two main types of software: Software can also be categorized by how it is deployed . Traditional applications are purchased with a perpetual license for

6527-475: The compiler recompiled from original source with the compromised compiler executable: the backdoor has been bootstrapped. This attack dates to a 1974 paper by Karger and Schell, and was popularized in Thompson's 1984 article, entitled "Reflections on Trusting Trust"; it is hence colloquially known as the "Trusting Trust" attack. See compiler backdoors , below, for details. Analogous attacks can target lower levels of

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6634-588: The compiler was. It is believed that the Induc-A virus had been propagating for at least a year before it was discovered. In 2015, a malicious copy of Xcode, XcodeGhost , also performed a similar attack and infected iOS apps from a dozen of software companies in China. Globally, 4,000 apps were found to be affected. It was not a true Thompson Trojan, as it does not infect development tools themselves, but it did prove that toolchain poisoning can cause substantial damages. Once

6741-443: The compiler, this in turn can be fixed by recompiling the compiler, removing the backdoor insertion code. This defense can in turn be subverted by putting a source meta-backdoor in the compiler, so that when it detects that it is compiling itself it then inserts this meta-backdoor generator, together with the original backdoor generator for the original program under attack. After this is done, the source meta-backdoor can be removed, and

6848-450: The compiler-under-test. That source, compiled with both compilers, results in two different stage-1 compilers, which however should have the same behavior. Thus the same source compiled with both stage-1 compilers must then result in two identical stage-2 compilers. A formal proof is given that the latter comparison guarantees that the purported source code and executable of the compiler-under-test correspond, under some assumptions. This method

6955-404: The correctness of code, while user acceptance testing helps to ensure that the product meets customer expectations. There are a variety of software development methodologies , which vary from completing all steps in order to concurrent and iterative models. Software development is driven by requirements taken from prospective users, as opposed to maintenance, which is driven by events such as

7062-400: The cost of poor quality software can be as high as 20 to 40 percent of sales. Despite developers' goal of delivering a product that works entirely as intended, virtually all software contains bugs. The rise of the Internet also greatly increased the need for computer security as it enabled malicious actors to conduct cyberattacks remotely. If a bug creates a security risk, it is called

7169-419: The cost of products. Unlike copyrights, patents generally only apply in the jurisdiction where they were issued. Engineer Capers Jones writes that "computers and software are making profound changes to every aspect of human life: education, work, warfare, entertainment, medicine, law, and everything else". It has become ubiquitous in everyday life in developed countries . In many cases, software augments

7276-414: 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

7383-435: The expanded reliance on computer systems , the Internet , and wireless network standards . Its importance 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

7490-464: 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

7597-456: 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

7704-438: The form of commercial off-the-shelf (COTS) or open-source software . Software quality assurance is typically a combination of manual code review by other engineers and automated software testing . Due to time constraints, testing cannot cover all aspects of the software's intended functionality, so developers often focus on the most critical functionality. Formal methods are used in some safety-critical systems to prove

7811-439: The functionality of existing technologies such as household appliances and elevators . Software also spawned entirely new technologies such as the Internet , video games , mobile phones , and GPS . New methods of communication, including email , forums , blogs , microblogging , wikis , and social media , were enabled by the Internet. Massive amounts of knowledge exceeding any paper-based library are now available with

7918-580: The infected machines. Others, such as the Sony/BMG rootkit , placed secretly on millions of music CDs through late 2005, are intended as DRM measures—and, in that case, as data-gathering agents , since both surreptitious programs they installed routinely contacted central servers. A sophisticated attempt to plant a backdoor in the Linux kernel , exposed in November 2003, added a small and subtle code change by subverting

8025-486: 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

8132-447: 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"

8239-456: The machine code of the untrusted compiler before using it. As mentioned above, there are ways to hide the Trojan horse, such as subverting the disassembler; but there are ways to counter that defense, too, such as writing a disassembler from scratch. A generic method to counter trusting trust attacks is called diverse double-compiling . The method requires a different compiler and the source code of

8346-514: 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

8453-479: The manufacturer with a way to restore user passwords. Many systems that store information within the cloud fail to create accurate security measures. If many systems are connected within the cloud , hackers can gain access to all other platforms through the most vulnerable system. Default passwords (or other default credentials) can function as backdoors if they are not changed by the user. Some debugging features can also act as backdoors if they are not removed in

8560-597: The mid-1970s and is vested in the company that makes the software, not the employees or contractors who wrote it. The use of most software is governed by an agreement ( software license ) between the copyright holder and the user. Proprietary software is usually sold under a restrictive license that limits copying and reuse (often enforced with tools such as digital rights management (DRM)). Open-source licenses , in contrast, allow free use and redistribution of software with few conditions. Most open-source licenses used for software require that modifications be released under

8667-472: 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

8774-486: The object code. Further, object code backdoors can be removed (assuming source code is available) by simply recompiling from source on a trusted system. Thus for such backdoors to avoid detection, all extant copies of a binary must be subverted, and any validation checksums must also be compromised, and source must be unavailable, to prevent recompilation. Alternatively, these other tools (length checks, diff, checksumming, disassemblers) can themselves be compromised to conceal

8881-558: 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

8988-472: The operating system) can take this saved file and execute it as a process on the computer hardware. Some programming languages use an interpreter instead of a compiler. An interpreter converts the program into machine code at run time , which makes them 10 to 100 times slower than compiled programming languages. Software is often released with the knowledge that it is incomplete or contains bugs. Purchasers knowingly buy it in this state, which has led to

9095-493: The original exploit in 2002, and, in 2009, Wheeler wrote a historical overview and survey of the literature. In 2023, Cox published an annotated version of Thompson's backdoor source code. Thompson's version was, officially, never released into the wild. However, it is believed that a version was distributed to BBN and at least one use of the backdoor was recorded. There are scattered anecdotal reports of such backdoors in subsequent years. In August 2009, an attack of this kind

9202-548: The physical world may also be part of the requirements for a software patent to be held valid. Software patents have been historically controversial . Before the 1998 case State Street Bank & Trust Co. v. Signature Financial Group, Inc. , software patents were generally not recognized in the United States. In that case, the Supreme Court decided that business processes could be patented. Patent applications are complex and costly, and lawsuits involving patents can drive up

9309-427: 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

9416-573: The release version. In 1993, the United States government attempted to deploy an encryption system, the Clipper chip , with an explicit backdoor for law enforcement and national security access. The chip was unsuccessful. Recent proposals to counter backdoors include creating a database of backdoors' triggers and then using neural networks to detect them. The threat of backdoors surfaced when multiuser and networked operating systems became widely adopted. Petersen and Turn discussed computer subversion in

9523-408: The release. Over time, the level of maintenance becomes increasingly restricted before being cut off entirely when the product is withdrawn from the market. As software ages , it becomes known as legacy software and can remain in use for decades, even if there is no one left who knows how to fix it. Over the lifetime of the product, software maintenance is estimated to comprise 75 percent or more of

9630-476: 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

9737-424: The same license, which can create complications when open-source software is reused in proprietary projects. Patents give an inventor an exclusive, time-limited license for a novel product or process. Ideas about what software could accomplish are not protected by law and concrete implementations are instead covered by copyright law . In some countries, a requirement for the claimed invention to have an effect on

9844-399: The second task, the compiler's source code would appear "clean".) What's worse, in Thompson's proof of concept implementation, the subverted compiler also subverted the analysis program (the disassembler ), so that anyone who examined the binaries in the usual way would not actually see the real code that was running, but something else instead. Karger and Schell gave an updated analysis of

9951-429: 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

10058-431: 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

10165-447: 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

10272-476: The source code, and the resulting compromised compiler (object code) can compile the original (unmodified) source code and insert itself: the exploit has been boot-strapped. This attack was originally presented in Karger & Schell (1974), which was a United States Air Force security analysis of Multics , where they described such an attack on a PL/I compiler, and call it a "compiler trap door". They also mention

10379-452: The system and tools being needed to conceal a single change. As object code can be regenerated by recompiling (reassembling, relinking) the original source code, making a persistent object code backdoor (without modifying source code) requires subverting the compiler itself—so that when it detects that it is compiling the program under attack it inserts the backdoor—or alternatively the assembler, linker, or loader. As this requires subverting

10486-486: The system through a rootkit ), code in the firmware of the hardware, or parts of an operating system such as Windows . Trojan horses can be used to create vulnerabilities in a device. A Trojan horse may appear to be an entirely legitimate program, but when executed, it triggers an activity that may install a backdoor. Although some are secretly installed, other backdoors are deliberate and widely known. These kinds of backdoors have "legitimate" uses such as providing

10593-669: 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,

10700-600: The system, such as the operating system, and can be inserted during the system booting process; these are also mentioned by Karger and Schell in 1974, and now exist in the form of boot sector viruses . A traditional backdoor is a symmetric backdoor: anyone that finds the backdoor can in turn use it. The notion of an asymmetric backdoor was introduced by Adam Young and Moti Yung in the Proceedings of Advances in Cryptology – Crypto '96 . An asymmetric backdoor can only be used by

10807-425: 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

10914-431: The total development cost. Completing a software project involves various forms of expertise, not just in software programmers but also testing, documentation writing, project management , graphic design , user experience , user support, marketing , and fundraising. Software quality is defined as meeting the stated requirements as well as customer expectations. Quality is an overarching term that can refer to

11021-425: 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

11128-613: 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

11235-492: Was applied by its author to verify that the C compiler of the GCC suite (v. 3.0.4) contained no trojan, using icc (v. 11.0) as the different compiler. In practice such verifications are not done by end users, except in extreme circumstances of intrusion detection and analysis, due to the rarity of such sophisticated attacks, and because programs are typically distributed in binary form. Removing backdoors (including compiler backdoors)

11342-462: Was discovered by Sophos labs. The W32/Induc-A virus infected the program compiler for Delphi , a Windows programming language. The virus introduced its own code to the compilation of new Delphi programs, allowing it to infect and propagate to many systems, without the knowledge of the software programmer. The virus looks for a Delphi installation, modifies the SysConst.pas file, which is the source code of

11449-401: Was simultaneous with the compilers needed to translate them automatically into machine code. Most programs do not contain all the resources needed to run them and rely on external libraries . Part of the compiler's function is to link these files in such a way that the program can be executed by the hardware. Once compiled, the program can be saved as an object file and the loader (part of

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