A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. It often uses a computer network to spread itself, relying on security failures on the target computer to access it. It will use this machine as a host to scan and infect other computers. When these new worm-invaded computers are controlled, the worm will continue to scan and infect other computers using these computers as hosts, and this behaviour will continue. Computer worms use recursive methods to copy themselves without host programs and distribute themselves based on exploiting the advantages of exponential growth , thus controlling and infecting more and more computers in a short time. Worms almost always cause at least some harm to the network, even if only by consuming bandwidth , whereas viruses almost always corrupt or modify files on a targeted computer.
63-508: Welchia , also known as the " Nachi worm ", is a computer worm that exploits a vulnerability in the Microsoft remote procedure call (RPC) service similar to the Blaster worm . However, unlike Blaster, it first searches for and deletes Blaster if it exists, then tries to download and install security patches from Microsoft that would prevent further infection by Blaster, so it is classified as
126-507: A computer terminal (until the 1990s) to a graphical user interface (GUI) computer. Computer terminals limited programmers to a single shell running in a command-line environment . During the 1970s, full-screen source code editing became possible through a text-based user interface . Regardless of the technology available, the goal is to program in a programming language . Programming language features exist to provide building blocks to be combined to express programming ideals. Ideally,
189-523: A helpful worm . Welchia was successful in deleting Blaster, but Microsoft claimed that it was not always successful in applying their security patch. This worm infected systems by exploiting vulnerabilities in Microsoft Windows system code ( TFTPD.EXE and TCP on ports 666–765, and a buffer overflow of the RPC on port 135). Its method of infection is to create a remote shell and instruct the system to download
252-462: A list of integers could be called integer_list . In object-oriented jargon, abstract datatypes are called classes . However, a class is only a definition; no memory is allocated. When memory is allocated to a class and bound to an identifier , it is called an object . Object-oriented imperative languages developed by combining the need for classes and the need for safe functional programming . A function, in an object-oriented language,
315-523: A stored-program computer loads its instructions into memory just like it loads its data into memory. As a result, the computer could be programmed quickly and perform calculations at very fast speeds. Presper Eckert and John Mauchly built the ENIAC. The two engineers introduced the stored-program concept in a three-page memo dated February 1944. Later, in September 1944, John von Neumann began working on
378-401: A color display and keyboard that was packaged in a single console. The disk operating system was programmed using IBM's Basic Assembly Language (BAL) . The medical records application was programmed using a BASIC interpreter. However, the computer was an evolutionary dead-end because it was extremely expensive. Also, it was built at a public university lab for a specific purpose. Nonetheless,
441-619: A host program, as it is an independent program or code chunk. Therefore, it is not restricted by the host program , but can run independently and actively carry out attacks. Exploit attacks Because a worm is not limited by the host program, worms can take advantage of various operating system vulnerabilities to carry out active attacks. For example, the " Nimda " virus exploits vulnerabilities to attack. Complexity Some worms are combined with web page scripts, and are hidden in HTML pages using VBScript , ActiveX and other technologies. When
504-451: A large number of vulnerabilities in the network. Any code designed to do more than spread the worm is typically referred to as the " payload ". Typical malicious payloads might delete files on a host system (e.g., the ExploreZip worm), encrypt files in a ransomware attack, or exfiltrate data such as confidential documents or passwords. Some worms may install a backdoor . This allows
567-519: A machine, then the majority of worms are unable to spread to it. If a vulnerability is disclosed before the security patch released by the vendor, a zero-day attack is possible. Users need to be wary of opening unexpected emails, and should not run attached files or programs, or visit web sites that are linked to such emails. However, as with the ILOVEYOU worm, and with the increased growth and efficiency of phishing attacks, it remains possible to trick
630-509: A major contributor. The statements were English-like and verbose. The goal was to design a language so managers could read the programs. However, the lack of structured statements hindered this goal. COBOL's development was tightly controlled, so dialects did not emerge to require ANSI standards. As a consequence, it was not changed for 15 years until 1974. The 1990s version did make consequential changes, like object-oriented programming . ALGOL (1960) stands for "ALGOrithmic Language". It had
693-548: A process. The interpreter then loads the source code into memory to translate and execute each statement . Running the source code is slower than running an executable . Moreover, the interpreter must be installed on the computer. The "Hello, World!" program is used to illustrate a language's basic syntax . The syntax of the language BASIC (1964) was intentionally limited to make the language easy to learn. For example, variables are not declared before being used. Also, variables are automatically initialized to zero. Here
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#1732847932955756-521: A profound influence on programming language design. Emerging from a committee of European and American programming language experts, it used standard mathematical notation and had a readable, structured design. Algol was first to define its syntax using the Backus–Naur form . This led to syntax-directed compilers. It added features like: Algol's direct descendants include Pascal , Modula-2 , Ada , Delphi and Oberon on one branch. On another branch
819-466: A programming language should: The programming style of a programming language to provide these building blocks may be categorized into programming paradigms . For example, different paradigms may differentiate: Each of these programming styles has contributed to the synthesis of different programming languages . A programming language is a set of keywords , symbols , identifiers , and rules by which programmers can communicate instructions to
882-611: A series of Microsoft patches. It then attempts to remove the Blaster Worm by deleting MSBLAST.EXE. If still in the system, the worm is programmed to self-remove on January 1, 2004, or after 120 days of processing, whichever comes first. In September 2003, the worm was discovered on the US State Department's computer network, causing them to shut down their network for 9 hours for remediation. Computer worm Many worms are designed only to spread, and do not attempt to change
945-494: A syntax that would likely fail IBM's compiler. The American National Standards Institute (ANSI) developed the first Fortran standard in 1966. In 1978, Fortran 77 became the standard until 1991. Fortran 90 supports: COBOL (1959) stands for "COmmon Business Oriented Language". Fortran manipulated symbols. It was soon realized that symbols did not need to be numbers, so strings were introduced. The US Department of Defense influenced COBOL's development, with Grace Hopper being
1008-469: A technological improvement to refine the production of field-effect transistors (1963). The goal is to alter the electrical resistivity and conductivity of a semiconductor junction . First, naturally occurring silicate minerals are converted into polysilicon rods using the Siemens process . The Czochralski process then converts the rods into a monocrystalline silicon , boule crystal . The crystal
1071-514: A user accesses a webpage containing a virus, the virus automatically resides in memory and waits to be triggered. There are also some worms that are combined with backdoor programs or Trojan horses , such as " Code Red ". Contagiousness Worms are more infectious than traditional viruses. They not only infect local computers, but also all servers and clients on the network based on the local computer. Worms can easily spread through shared folders , e-mails , malicious web pages, and servers with
1134-542: Is an example computer program, in Basic, to average a list of numbers: Once the mechanics of basic computer programming are learned, more sophisticated and powerful languages are available to build large computer systems. Improvements in software development are the result of improvements in computer hardware . At each stage in hardware's history, the task of computer programming changed dramatically. In 1837, Jacquard's loom inspired Charles Babbage to attempt to build
1197-418: Is assigned to a class. An assigned function is then referred to as a method , member function , or operation . Object-oriented programming is executing operations on objects . Object-oriented languages support a syntax to model subset/superset relationships. In set theory , an element of a subset inherits all the attributes contained in the superset. For example, a student is a person. Therefore,
1260-453: Is called source code . Source code needs another computer program to execute because computers can only execute their native machine instructions . Therefore, source code may be translated to machine instructions using a compiler written for the language. ( Assembly language programs are translated using an assembler .) The resulting file is called an executable . Alternatively, source code may execute within an interpreter written for
1323-442: Is known as the x86 series . The x86 assembly language is a family of backward-compatible machine instructions . Machine instructions created in earlier microprocessors were retained throughout microprocessor upgrades. This enabled consumers to purchase new computers without having to purchase new application software . The major categories of instructions are: VLSI circuits enabled the programming environment to advance from
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#17328479329551386-427: Is then thinly sliced to form a wafer substrate . The planar process of photolithography then integrates unipolar transistors, capacitors , diodes , and resistors onto the wafer to build a matrix of metal–oxide–semiconductor (MOS) transistors. The MOS transistor is the primary component in integrated circuit chips . Originally, integrated circuit chips had their function set during manufacturing. During
1449-623: The ARPANET and delete the experimental Creeper program (the first computer worm, 1971). On November 2, 1988, Robert Tappan Morris , a Cornell University computer science graduate student, unleashed what became known as the Morris worm , disrupting many computers then on the Internet, guessed at the time to be one tenth of all those connected. During the Morris appeal process, the U.S. Court of Appeals estimated
1512-502: The Analytical Engine . The names of the components of the calculating device were borrowed from the textile industry. In the textile industry, yarn was brought from the store to be milled. The device had a store which consisted of memory to hold 1,000 numbers of 50 decimal digits each. Numbers from the store were transferred to the mill for processing. The engine was programmed using two sets of perforated cards. One set directed
1575-600: The Busicom calculator. Five months after its release, Intel released the Intel 8008 , an 8-bit microprocessor. Bill Pentz led a team at Sacramento State to build the first microcomputer using the Intel 8008: the Sac State 8008 (1972). Its purpose was to store patient medical records. The computer supported a disk operating system to run a Memorex , 3- megabyte , hard disk drive . It had
1638-541: The Ethernet principles on their network of Xerox Alto computers. Similarly, the Nachi family of worms tried to download and install patches from Microsoft's website to fix vulnerabilities in the host system by exploiting those same vulnerabilities. In practice, although this may have made these systems more secure, it generated considerable network traffic, rebooted the machine in the course of patching it, and did its work without
1701-455: The 1960s, controlling the electrical flow migrated to programming a matrix of read-only memory (ROM). The matrix resembled a two-dimensional array of fuses. The process to embed instructions onto the matrix was to burn out the unneeded connections. There were so many connections, firmware programmers wrote a computer program on another chip to oversee the burning. The technology became known as Programmable ROM . In 1971, Intel installed
1764-578: The ENIAC project. On June 30, 1945, von Neumann published the First Draft of a Report on the EDVAC , which equated the structures of the computer with the structures of the human brain. The design became known as the von Neumann architecture . The architecture was simultaneously deployed in the constructions of the EDVAC and EDSAC computers in 1949. The IBM System/360 (1964) was a family of computers, each having
1827-600: The ENIAC took up to two months. Three function tables were on wheels and needed to be rolled to fixed function panels. Function tables were connected to function panels by plugging heavy black cables into plugboards . Each function table had 728 rotating knobs. Programming the ENIAC also involved setting some of the 3,000 switches. Debugging a program took a week. It ran from 1947 until 1955 at Aberdeen Proving Ground , calculating hydrogen bomb parameters, predicting weather patterns, and producing firing tables to aim artillery guns. Instead of plugging in cords and turning switches,
1890-538: The Internet randomly, looking for vulnerable hosts to infect. In addition, machine learning techniques can be used to detect new worms, by analyzing the behavior of the suspected computer. A helpful worm or anti-worm is a worm designed to do something that its author feels is helpful, though not necessarily with the permission of the executing computer's owner. Beginning with the first research into worms at Xerox PARC , there have been attempts to create useful worms. Those worms allowed John Shoch and Jon Hupp to test
1953-476: The computer program onto the chip and named it the Intel 4004 microprocessor . The terms microprocessor and central processing unit (CPU) are now used interchangeably. However, CPUs predate microprocessors. For example, the IBM System/360 (1964) had a CPU made from circuit boards containing discrete components on ceramic substrates . The Intel 4004 (1971) was a 4- bit microprocessor designed to run
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2016-463: The computer to be remotely controlled by the worm author as a " zombie ". Networks of such machines are often referred to as botnets and are very commonly used for a range of malicious purposes, including sending spam or performing DoS attacks. Some special worms attack industrial systems in a targeted manner. Stuxnet was primarily transmitted through LANs and infected thumb-drives, as its targets were never connected to untrusted networks, like
2079-461: The computer. They follow a set of rules called a syntax . Programming languages get their basis from formal languages . The purpose of defining a solution in terms of its formal language is to generate an algorithm to solve the underlining problem. An algorithm is a sequence of simple instructions that solve a problem. The evolution of programming languages began when the EDSAC (1949) used
2142-436: The consent of the computer's owner or user. Regardless of their payload or their writers' intentions, security experts regard all worms as malware . Another example of this approach is Roku OS patching a bug allowing for Roku OS to be rooted via an update to their screensaver channels, which the screensaver would attempt to connect to the telnet and patch the device. One study proposed the first computer worm that operates on
2205-452: The continental net a self-perpetuating tapeworm, probably headed by a denunciation group "borrowed" from a major corporation, which would shunt itself from one nexus to another every time his credit-code was punched into a keyboard. It could take days to kill a worm like that, and sometimes weeks." The second ever computer worm was devised to be an anti-virus software. Named Reaper , it was created by Ray Tomlinson to replicate itself across
2268-589: The cost of removing the worm from each installation at between $ 200 and $ 53,000; this work prompted the formation of the CERT Coordination Center and Phage mailing list. Morris himself became the first person tried and convicted under the 1986 Computer Fraud and Abuse Act . Conficker , a computer worm discovered in 2008 that primarily targeted Microsoft Windows operating systems, is a worm that employs three different spreading strategies: local probing, neighborhood probing, and global probing. This worm
2331-434: The descendants include C , C++ and Java . BASIC (1964) stands for "Beginner's All-Purpose Symbolic Instruction Code". It was developed at Dartmouth College for all of their students to learn. If a student did not go on to a more powerful language, the student would still remember Basic. A Basic interpreter was installed in the microcomputers manufactured in the late 1970s. As the microcomputer industry grew, so did
2394-508: The embedded programmable logic controllers of industrial machines. Although these systems operate independently from the network, if the operator inserts a virus-infected drive into the system's USB interface, the virus will be able to gain control of the system without any other operational requirements or prompts. Worms spread by exploiting vulnerabilities in operating systems. Vendors with security problems supply regular security updates (see " Patch Tuesday "), and if these are installed to
2457-551: The end-user into running malicious code. Anti-virus and anti-spyware software are helpful, but must be kept up-to-date with new pattern files at least every few days. The use of a firewall is also recommended. Users can minimize the threat posed by worms by keeping their computers' operating system and other software up to date, avoiding opening unrecognized or unexpected emails and running firewall and antivirus software. Mitigation techniques include: Infections can sometimes be detected by their behavior - typically scanning
2520-643: The first stored computer program in its von Neumann architecture . Programming the EDSAC was in the first generation of programming language . Imperative languages specify a sequential algorithm using declarations , expressions , and statements : FORTRAN (1958) was unveiled as "The IBM Mathematical FORmula TRANslating system". It was designed for scientific calculations, without string handling facilities. Along with declarations , expressions , and statements , it supported: It succeeded because: However, non-IBM vendors also wrote Fortran compilers, but with
2583-539: The halt state. All present-day computers are Turing complete . The Electronic Numerical Integrator And Computer (ENIAC) was built between July 1943 and Fall 1945. It was a Turing complete , general-purpose computer that used 17,468 vacuum tubes to create the circuits . At its core, it was a series of Pascalines wired together. Its 40 units weighed 30 tons, occupied 1,800 square feet (167 m ), and consumed $ 650 per hour ( in 1940s currency ) in electricity when idle. It had 20 base-10 accumulators . Programming
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2646-623: The internet. This virus can destroy the core production control computer software used by chemical, power generation and power transmission companies in various countries around the world - in Stuxnet's case, Iran, Indonesia and India were hardest hit - it was used to "issue orders" to other equipment in the factory, and to hide those commands from being detected. Stuxnet used multiple vulnerabilities and four different zero-day exploits (e.g.: [1] ) in Windows systems and Siemens SIMATICWinCC systems to attack
2709-475: The language BCPL was replaced with B , and AT&T Bell Labs called the next version "C". Its purpose was to write the UNIX operating system . C is a relatively small language, making it easy to write compilers. Its growth mirrored the hardware growth in the 1980s. Its growth also was because it has the facilities of assembly language , but uses a high-level syntax . It added advanced features like: C allows
2772-400: The language. Basic pioneered the interactive session . It offered operating system commands within its environment: However, the Basic syntax was too simple for large programs. Recent dialects added structure and object-oriented extensions. Microsoft's Visual Basic is still widely used and produces a graphical user interface . C programming language (1973) got its name because
2835-410: The language. If the executable is requested for execution, then the operating system loads it into memory and starts a process . The central processing unit will soon switch to this process so it can fetch, decode, and then execute each machine instruction. If the source code is requested for execution, then the operating system loads the corresponding interpreter into memory and starts
2898-478: The operation and the other set inputted the variables. However, the thousands of cogged wheels and gears never fully worked together. Ada Lovelace worked for Charles Babbage to create a description of the Analytical Engine (1843). The description contained Note G which completely detailed a method for calculating Bernoulli numbers using the Analytical Engine. This note is recognized by some historians as
2961-438: The performance of massive scale ephemeral artworks. It turns the infected computers into nodes that contribute to the artwork. Computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute . It is one component of software , which also includes documentation and other intangible components. A computer program in its human-readable form
3024-410: The powerful men who run a national electronic information web that induces mass conformity. "You have the biggest-ever worm loose in the net, and it automatically sabotages any attempt to monitor it. There's never been a worm with that tough a head or that long a tail!" "Then the answer dawned on him, and he almost laughed. Fluckner had resorted to one of the oldest tricks in the store and turned loose in
3087-443: The programmer to control which region of memory data is to be stored. Global variables and static variables require the fewest clock cycles to store. The stack is automatically used for the standard variable declarations . Heap memory is returned to a pointer variable from the malloc() function. In the 1970s, software engineers needed language support to break large projects down into modules . One obvious feature
3150-501: The project contributed to the development of the Intel 8080 (1974) instruction set . In 1978, the modern software development environment began when Intel upgraded the Intel 8080 to the Intel 8086 . Intel simplified the Intel 8086 to manufacture the cheaper Intel 8088 . IBM embraced the Intel 8088 when they entered the personal computer market (1981). As consumer demand for personal computers increased, so did Intel's microprocessor development. The succession of development
3213-446: The same instruction set architecture . The Model 20 was the smallest and least expensive. Customers could upgrade and retain the same application software . The Model 195 was the most premium. Each System/360 model featured multiprogramming —having multiple processes in memory at once. When one process was waiting for input/output , another could compute. IBM planned for each model to be programmed using PL/1 . A committee
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#17328479329553276-455: The same deficiencies exploited by the Blaster worm , Welchia infected computers and automatically began downloading Microsoft security updates for Windows without the users' consent. Welchia automatically reboots the computers it infects after installing the updates. One of these updates was the patch that fixed the exploit. Other examples of helpful worms are "Den_Zuko", "Cheeze", "CodeGreen", and "Millenium". Art worms support artists in
3339-519: The second layer of the OSI model (Data link Layer), utilizing topology information such as Content-addressable memory (CAM) tables and Spanning Tree information stored in switches to propagate and probe for vulnerable nodes until the enterprise network is covered. Anti-worms have been used to combat the effects of the Code Red , Blaster , and Santy worms. Welchia is an example of a helpful worm. Utilizing
3402-438: The set of students is a subset of the set of persons. As a result, students inherit all the attributes common to all persons. Additionally, students have unique attributes that other people do not have. Object-oriented languages model subset/superset relationships using inheritance . Object-oriented programming became the dominant language paradigm by the late 1990s. C++ (1985) was originally called "C with Classes". It
3465-462: The systems they pass through. However, as the Morris worm and Mydoom showed, even these "payload-free" worms can cause major disruption by increasing network traffic and other unintended effects. The term "worm" was first used in this sense in John Brunner 's 1975 novel, The Shockwave Rider . In the novel, Nichlas Haflinger designs and sets off a data-gathering worm in an act of revenge against
3528-499: The world's first computer program . In 1936, Alan Turing introduced the Universal Turing machine , a theoretical device that can model every computation. It is a finite-state machine that has an infinitely long read/write tape. The machine can move the tape back and forth, changing its contents as it performs an algorithm . The machine starts in the initial state, goes through a sequence of steps, and halts when it encounters
3591-452: The worm using TFTP.EXE. Specifically, the Welchia worm targeted machines running Windows XP. The worm used ICMP , and in some instances flooded networks with enough ICMP traffic to cause problems. Once on the system, the worm patches the vulnerability it used to gain access (thereby actually securing the system against other attempts to exploit the same method of intrusion) and run its payload,
3654-452: Was considered a hybrid epidemic and affected millions of computers. The term "hybrid epidemic" is used because of the three separate methods it employed to spread, which was discovered through code analysis. Independence Computer viruses generally require a host program. The virus writes its own code into the host program. When the program runs, the written virus program is executed first, causing infection and damage. A worm does not need
3717-474: Was designed to expand C's capabilities by adding the object-oriented facilities of the language Simula . An object-oriented module is composed of two files. The definitions file is called the header file . Here is a C++ header file for the GRADE class in a simple school application: A constructor operation is a function with the same name as the class name. It is executed when the calling operation executes
3780-437: Was formed that included COBOL , Fortran and ALGOL programmers. The purpose was to develop a language that was comprehensive, easy to use, extendible, and would replace Cobol and Fortran. The result was a large and complex language that took a long time to compile . Computers manufactured until the 1970s had front-panel switches for manual programming. The computer program was written on paper for reference. An instruction
3843-408: Was represented by a configuration of on/off settings. After setting the configuration, an execute button was pressed. This process was then repeated. Computer programs also were automatically inputted via paper tape , punched cards or magnetic-tape . After the medium was loaded, the starting address was set via switches, and the execute button was pressed. A major milestone in software development
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#17328479329553906-531: Was the invention of the Very Large Scale Integration (VLSI) circuit (1964). Following World War II , tube-based technology was replaced with point-contact transistors (1947) and bipolar junction transistors (late 1950s) mounted on a circuit board . During the 1960s , the aerospace industry replaced the circuit board with an integrated circuit chip . Robert Noyce , co-founder of Fairchild Semiconductor (1957) and Intel (1968), achieved
3969-405: Was to decompose large projects physically into separate files . A less obvious feature was to decompose large projects logically into abstract data types . At the time, languages supported concrete (scalar) datatypes like integer numbers, floating-point numbers, and strings of characters . Abstract datatypes are structures of concrete datatypes, with a new name assigned. For example,
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