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Who writes computer viruses?
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Virus authors are normally 14-26 year old males who spend a lot of time on their computers. Some of them want to prove they are good programmers. Others want to show that they have the power to cause large-scale problems.
But most viruses don't constitute good programming, as many fail to deliver their payload. Many are re-hashed versions of old programs that require little skill to produce.
The law. In the UK, if you're caught using a computer for criminal reasons you can receive a 5-year sentence and an unlimited fine. If convicted of 'cyberterrorism1, then you can be given the same sentence as a terrorist bomber.
How do you catch a virus writer?
Although the Internet allows computer viruses to spread quickly, it also helps to catch the authors.
Each computer connected to the Internet has an address, similar to a phone number. This is called an IP address and looks like this: 128.5.10.64. Every e-mail you send is Hunting hackers marked with your IP address and this information is hard to remove.
Your IP address reveals what company (or Internet Service Provider) holds your account. The company can then find out which customer sent the mail. So if you send a virus to a Member of Parliament, it won't be long before the police are knocking on your door asking questions.
Sophisticated virus authors would be able to cover their tracks to some degree, but there is usually some way to track them down.
Hackers, crackers and script kiddies
There's a whole zoo of cantankerous coders out there:
Hackers: people who try to find security flaws in corporate computer programs. Most hackers don't aim to cause problems, but they might send an anonymous email to the person in charge warning them of their security problem. Amongst other hackers, there is much honour to be gained by those who can 'crack the uncrackable programs
Crackers: unlike hackers; crackers are less sophisticated. They like to break into people's websites and replace their corporate homepage either with pornographic images or hoax messages
Script kiddies: young virus pirates, who copy old computer viruses and modify them. Often they don’t work. If they do, they are seldom as dangerous as the originals and can be easily destroyed.
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Types of virus
From worms to macros, there's a whole host of viruses out there to catch...
Worms. These viruses spread via computer networks. The ILOVEYOU virus was a classic example of a worm. These viruses are becoming an Increasing threat as a growing number of computers are permanently connected to networks. Worms can spread over corporate networks or via emails sent over the Internet.
Trojans. A Trojan virus takes its name from a story in Homer's Iliad where Greek soldiers pretended to make peace with their enemies, the Trojans. The Greeks made a grand peace-keeping gesture – the gift of a large wooden horse.
When the Trojans hauled it inside their city gates, a small band of Greek warriors leapt out. They opened the gates and let the rest of the Greek army storm in to capture the city.
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A Trojan virus is one that opens your computer up to malicious intruders, allowing them to read your files.
File viruses. A file virus is one that replaces a key system file on your computer. These viruses can reload themselves every time you start your computer up. Once they're in the memory, they can spread by writing themselves to any disk you insert into your disk drive.
Boot sector viruses. This is an early type of computer virus that spreads by hiding itself in an invisible location on your hard drive or floppy disk. When your computer reads an infected floppy disk, the virus is copied from the disk to your computer's memory.
From there, it writes itself to the 'boot sector' on your hard drive. The boot sector is read each time you turn your computer on. So the virus is constantly reloaded and can copy itself on to other floppy disks. These viruses are fairly rare nowadays, as they are easy to catch.
Macroviruses. A macrovirus infects word processor files, such as Microsoft Word documents. Although not as dangerous as other viruses, they can spread quickly if a Word file is sent via email. After an initial scare, Microsoft added protection into later versions of Word, so you receive a warning about infected documents.
Hoaxes. The virus hoax came about after friends sent each other emails about a new virus threat. Someone decided that they could cause just as much trouble by sending out fake warnings rather than real viruses.
Hoaxes may seem harmless, but they do a great deal of damage to the Internet as a whole. Not only do they slow down traffic and clog up email servers, but they also cause people to panic. Companies can spend money and time investigating what is just someone's idea of a joke.
Mobile phone viruses
Although rare, mobile phones are the latest technology to be hit by virus problems. Some people have discovered that it is possible to crash certain types of mobile by sending them a coded text message.
Mobile phone viruses. A recent case in Spain started via email. When the user opens the attachment on their PC, the virus generates a "junk" text message (using a Spanish telecommunications company website) which is sent out to a random phone number. Anti-virus software companies say that the virus will not infect the mobile phone itself.
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Types of cyber-crime
Cyber-Crime (’computer crime') is any illegal behavior directed by means of electronic operations that targets the security of computer systems and the data processed by them. In a wider sense, 'computer - related crime' can be any illegal behavior committed by means of, or in relation to, a computer system or network, however, this is not cyber-crime.
The Tenth United Nations Congress on the Prevention of Crime and the Treatment of Offenders (Vienna, 10-17 April 2000) categorized five offenses as cyber-crime: unauthorized access, damage to computer data or programs, sabotage to hinder the functioning of a computer system or network, unauthorized interception of data to, from and within a system or network, and computer espionage.
The Cyber-Crime and Intellectual Property Theft program seeks to collect and disseminate data and research on six 'popular' categories of cyber-crime that directly impact citizens and consumers and to educate these groups on the scope and depth of the problem, as well as current policies and research aimed at addressing the issue.
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The categories of cyber-crime addressed are:
Financial: crimes which disrupt businesses' ability to conduct 'e-commerce' (or electronic commerce)
Piracy: - the act of copying copyrighted material. The personal computer and the Internet both offer new mediums for committing an 'old' crime. Online theft is defined as any type of 'piracy' that involves fee use of the Internet to market or distribute creative works protected by copyright.
Hacking: - the act of gaining unauthorized access to a computer system or network and in some cases making unauthorized use of this access. Hacking is also the act by which other forms of cyber-crime (e.g., fraud, terrorism, etc.) are committed.
Cyber-terrorism: - the effect of acts of hacking designed to cause terror. Like conventional terrorism, 'e-terrorism' is classified as such if the result of hacking is to cause violence against persons or property, or at least cause enough harm to generate fear.
Online-Pornography: - According to 18 USC 2252 and 18 USC 2252A, possessing or distributing child pornography is against federal law and under 47 USC 223 distributing pornography of any form to a minor is illegal. The Internet is merely a new medium for this 'old' crime, but how best to regulate this global medium of communication across international boundaries and age groups has sparked a great deal of controversy and debate.
In Schools: While the Internet can be a unique educational and recreational resource for children, it is important that they are educated about how to safely and responsibly use this powerful tool. The founding goal of this project is to encourage empowering children through knowledge of law, their rights, and how best to prevent misuse of the Internet.
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CENTRAL PROCESSING UNIT
The central processing unit (CPU) or central processor is the nerve center of any digital computer system, since it coordinates and controls the activities of all the other units and performs all the arithmetic and logic process to be applied to data. All program instructions to be executed must be held within the CPU, and all the data to be processed must be loaded first into this unit. It is convenient to consider the central processor to have three separate hardware sections: an internal or main memory, an arithmetic and logic unit, and a control unit. The role of the internal memory was discussed more detailed in the previous lesson. Now let us discuss the latter two sections.
The CPU has two functions: it must obtain instructions from the memory and interpret them, as well as perform the actual operations. The first function is executed by the control unit. This unit in its turn must perform two functions: it must interpret the instruction; then, on the basis of this interpretation tell the arithmetic and logic unit what to do next. The latter function is accomplished through the use of electronic signals. According to these two functions we can separate the part of the control unit that interprets or decodes the instruction called the instruction decoder from the part that generates the control signals called the control generator.
An instruction having been transmitted to the instruction decoder, where it is interpreted, the control generator senses this interpretation and then produces signals that tell the arithmetic unit which operation to perform. It also generates signals that choose the proper numbers from the memory and sends them to the arithmetic and logic unit at the proper time; and when operation has been performed, other control signals take the result from the arithmetic and logic unit back to the internal memory. After an instruction has been executed, the control generator produces signals that cause the next instruction to go from the memory to the instruction decoder. In this way the instructions are performed sequentially.
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The second function of the CPU is performed by the arithmetic and logic unit which does the actual operations. This unit is capable of performing automatically addition, subtraction, multiplication, division, comparing, selecting, and other mathematical and logical operations. Consider now what happens in the arithmetic and logic unit while an instruction is being executed. In most computers only one word at a time can be transferred between the arithmetic/logic unit and the memory. Hence, to perform an operation involving two arguments, the first argument must be transferred from the memory to the arithmetic/logic unit and stored there temporarily while the second argument is being transferred. The special memory cell in the arithmetic/logic unit for this purpose is called the accumulator. The operation being performed, the result is formed in the accumulator before it is transmitted back to memory.
Next consider the instruction decoder that interprets instruction. In order that the instruction decoder performs its function, it must constantly refer to the instruction being interpreted during the time control signals are being set up. To facilitate this, while an instruction is being executed it is stored in a special memory cell called the instruction register, located in the instruction decoder.
There is another memory cell located in the instruction decoder called the current-address register. The contents of this register are always the memory address from which the instruction being executed came. The reason for this is related to the fact that the address of the present instruction was given as part of the previous instruction.
For the computer designer to understand the work of CPU is quite necessary.
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