Программа по формированию навыков безопасного поведения на дорогах и улицах «Добрая дорога детства» 2
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Warming upEx. 1. Discussion.  (Taken from Oxford English for Information Technology by Eric H. Glendinning, John McEwan) Mainstream Ex. 2. Learning facts. 1. Read THE ANATOMY OF A VIRUS A biological virus is a very small, simple organism that infects living cells, known as the host, by attaching itself to them and using them to reproduce itself. This often causes harm to the host cells. Similarly, a computer virus is a very small program routine that infects a computer system and uses its resources to reproduce itself. It often does this by patching the operating system to enable it to detect program files, such as COM or EXE files. It then copies itself into those files. This sometimes causes harm to the host computer system. When the user runs an infected program, it is loaded into memory carrying the virus. The virus uses a common programming technique to stay resident in memory. It can then use a reproduction routine to infect other programs. This process continues until the computer is switched off. The virus may also contain a payload that remains dormant until a trigger event activates it, such as the user pressing a particular key. The payload can have a variety of forms. It might do something relatively harmless such as displaying a message on the monitor, screen or it might do something more destructive such as deleting files on the hard disk. When it infects a file, the virus replaces the first instruction in the host program with a command that changes the normal execution sequence. This type of command is known as a JUMP command and causes the virus instructions to be executed before the host program. The virus then returns control to the host program which then continues with its normal sequence of instructions and is executed in the normal way. To be a virus, a program only needs to have a reproduction routine that enables it to infect other programs. Viruses can, however, have four main parts. A misdirection routine that enables it to hide itself; a reproduction routine that allows it to copy itself to other programs; a trigger that causes the payload to be activated at a particular time or when a particular event takes place; and a payload that may be a fairly harmless joke or may be very destructive. A program that has a payload but does not have a reproduction routine is known as a Trojan. 2. Answer the questions
7 How does a Trojan differ from a virus? (Taken from Oxford English for Information Technology by Eric H. Glendinning, John McEwan) 3. Give Russian equivalents: payload boot load reload download trigger host program reproduction routine misdirection routine 4. Give English equivalents: воспроизводить внедряться выполнять 5. Translate: to stay resident to remain dormant normal execution sequence Ex. 3. Discussion. Discuss the following questions in the class, taking notes of the definitions.
Viruses. In computers, a virus is a program or programming code that replicates by being copied or initiating its copying to another program, computer boot sector or document. Viruses can be transmitted as attachments to an e-mail note or in a downloaded file, or be present on a diskette or CD. The immediate source of the e-mail note, downloaded file, or diskette you've received is usually unaware that it contains a virus. Some viruses wreak [ri:k] their effect as soon as their code is executed; other viruses lie dormant until circumstances cause their code to be executed by the computer. Some viruses are benign or playful in intent and effect ("Happy Birthday, Ludwig!") and some can be quite harmful, erasing data or causing your hard disk to require reformatting. A virus that replicates itself by resending itself as an e-mail attachment or as part of a network message is known as a worm. Generally, there are three main classes of viruses: File infectors. Some file infector viruses attach themselves to program files, usually selected .COM or .EXE files. Some can infect any program for which execution is requested, including .SYS, .OVL, .PRG, and .MNU files. When the program is loaded, the virus is loaded as well. Other file infector viruses arrive as wholly-contained programs or scripts sent as an attachment to an e-mail note. System or boot-record infectors. These viruses infect executable code found in certain system areas on a disk. They attach to the DOS boot sector on diskettes or the Master Boot Record on hard disks. A typical scenario (familiar to the author) is to receive a diskette from an innocent source that contains a boot disk virus. When your operating system is running, files on the diskette can be read without triggering the boot disk virus. However, if you leave the diskette in the drive, and then turn the computer off or reload the operating system, the computer will look first in your A drive, find the diskette with its boot disk virus, load it, and make it temporarily impossible to use your hard disk. (Allow several days for recovery.) This is why you should make sure you have a bootable floppy. Macro viruses. These are among the most common viruses, and they tend to do the least damage. Macro viruses infect your Microsoft Word application and typically insert unwanted words or phrases. The best protection against a virus is to know the origin of each program or file you load into your computer or open from your e-mail program. Since this is difficult, you can buy anti-virus software that can screen e-mail attachments and also check all of your files periodically and remove any viruses that are found. From time to time, you may get an e-mail message warning of a new virus. Unless the warning is from a source you recognize, chances are good that the warning is a virus hoax. The computer virus, of course, gets its name from the biological virus. The word itself comes from a Latin word meaning slimy liquid or poison. Ex. 4. Grammar and vocabulary. (Taken from Oxford English for Information Technology by Eric H. Glendinning, John McEwan) Expressing CAUSE and EFFECT. What is the relationship between these actions?
These events form part of a cause and effect chain. We can describe the links between each event in a number of ways: Using cause + to V or make + V. 1 A date or event occurs which causes the trigger routine to run. 2 A date or event occurs which makes the trigger routine run. Putting the events in sequence and using a causative verb. 3 The trigger routine runs, which activates the payload routine. Using a when clause. 4 When the trigger routine runs, the payioad routine activates. 1. Describe the effects of these viruses and other destructive programs. 1 logic bomb - example a A dismissed employee's name is deleted from the company's payroll. b A logic bomb is activated, с All payroll records are destroyed. 2 Form (Boot sector virus) a A certain date occurs. b A trigger routine is activated. с Keys beep when pressed and floppies are corrupted. 3 Beijing (Boot sector virus) a The operator starts up the computer for the one hundred and twenty-ninth time, b A trigger routine is activated, с The screen displays, 'Bloody! June 4,1989'. 4 AntiEXE a The infected program is run. b The boot sector is corrupted, с The disk content is overwritten, d Data is lost. 5 Cascade (File virus - COM files only) a A particular date occurs. b The payload is triggered. с Characters on a text mode screen slide down to the bottom. 6 macro virus-example a An infected document is opened in the wordprocessor. b The virus macro is executed. с The virus code is attached to the default template. d The user saves another document. e The virus code attaches to the saved document. f The saved document is opened in the wordprocessor. g The virus destroys data, displays a message or plays music. 2. Some verbs beginning or ending with en have a causative meaning. Replace the words in italics in these sentences with the appropriate form of en verb from this list.enable encrypt ensure encode enhance brighten encourage enlarge widen
10 You can make the picture on your monitor wider. (Taken from Oxford English for Information Technology by Eric H. Glendinning, John McEwan) Ex.5. Listening. Listen to the following virus definition and fill in the blanks in the summary: UNIT 4. TYPES AND MODIFICATIONS OF VIRUSES | ||||||||||||||||||||
