Types of Computer Viruses

Nowadays number of viruses is about 55.000. It increases constantly. New unknown types of viruses appear. To classify them becomes more and more difficult. In common they can be divided by three basic signs: a place of situating, used operation system and work algorithms. For example, according to these three classifications virus Chernobyl can be classified as a file infector and resident Windows virus. Further it will be explained what it means.

File Infectors

These are viruses that attach themselves to (or replace) COM and EXE files, although in some cases they can infect files with extensions SYS, DRV, BIN, OVL and OVY With this type of a virus, uninfected programs usually become infected when they are executed with the virus in memory. In other cases they are infected when they are opened (such as using the DOS DIR command) or the virus simply infects all of the files in the directory is run from (a direct infector). There are three groups of file infectors.

Viruses of the first group are called overwriting viruses because they overwrite their code into an infected file erasing contents. But these viruses are primitive and they can be found very quickly.

Oilier group is called parasitic or cavity viruses. The infected file is capable of work fully or partly. Viruses can copy itself into begin, middle or end of a file. They record their code in data known not to be used.

The third group is called companion viruses. They don't change files. They make double of infected file so when an infected file is being started a double file becomes managing, it means a virus. For example, companion viruses working with DOS use that DOS firstly runs COM. file. Viruses make double file with the same name and with extension COM and copiesitself in this file. During start of an infected file DOS runa COM. file with a virus firstly and then a virus starts anEXE file.

Sometimes companion viruses rename file will be infected and record their code in a double file with old name. For example, the file XCOPY.EX is renamed into XCOPY.EXD and a virus record itself in file XCOPY.EXE. When this file is started computer runs a virus code firstly and after the virus starts original XCOPY, saved as XCOPY.EXD. Viruses like these ones were found not only in DOS. They were found in Windows and OS / 2.

It is not only one way to make double files. For example there is a subgroup of companion viruses called path-companion viruses. They use special feature of DOS-PATH: hierarchical record of file location. The virus copies itself in a file with the same name but situated one level higher. In this case DOS will find a file with a virus.

Task 2. Answer the following questions:

Задание 2. Ответьте на следующие вопросы:

1. What is a computer virus?

2. How many types of viruses are there? What are they?

3. How many groups of file-Infector do you know?

4. What do companion viruses do?

5. What don't viruses do?

6. What do special feature of POS path-companion viruses use?

7. Computer viruses do spontaneously generate, don't they?

8. What viruses will erase your entire hard disk?

9. How are viruses divided?

10. Viruses don't necessarily let you know that they are there-even after they

do something destructive, do they?

Task 3. Match the English words given below with their Russian equivalents:

Задание 3. Соотнесите следующие слова с соответствующим переводом:

• a symptom • a viral code • software • direct infector • a bug • an infected program • a self-replication • a hard disk • destructive • a file infector • a damage • executable files • a malignant virus • a monitor • a computer chip • a computer virus • compressed files • a benign virus • macro virus • erasing contents • a work algorithm • an application • a resident virus • a place of situating

• файл-инфектор • повреждать • жесткий диск • злостный вирус • монитор • компьютерный вирус • программная ошибка • неопасный вирус • симптом • программное обеспечение • макровирус • вирусный код • место расположения • главный заразитель • сжатые файлы • зараженная программа • резидентный вирус • самоответ • исполнительные файлы • разрушение • стирающий содержание • алгоритм работы • компьютерные чипы • приложение

Task 4. Find the sentences with the words and word — combinations given below in the text:

Задание 4. Найдите в тексте предложения, содержащие нижеследующие слова и выражения:

• a segment of program code

• executable files

• a virus payload

• a viral code

• a partition from mounting

• DOS — based computer software

• Word and Excel macro viruses

• to make double of infected file

Task 5. Complete the following sentences corresponding to the contents of the text:

Задание 5. Закончите предложения:

1. Other group is called...

2. The third group is called....

3. Usually a virus has two distinct functions....

4. Computer viruses do not....

5. Sometime companion viruses rename file will be.

6. Virus copies itself in....

7. Chernobyl can be....

8. Viruses also don't.....

9. They must be …...

10. Viruses of the first group are called....

11. A virus is a piece of....

12. This could include erasing a disk... on your computer.

13. Some viruses programmed... your entire hard disk.

14.... on write-protected disks and... in the case of.....

15. These are viruses that....

Task 6. Say whether the statements given below are true or false:

Задание 6. Определите истинность или ложность следующих предложений:

1. Some of the more malignant viruses will erase your entire hard disk, or delete files.

2. Computer viruses do infect files on write-protected disks and do infect documents, except in the case of Word macro viruses, which infect only documents and templates written in Word 6.0 or higher.

3. Usually a virus has six distinct functions.

4. There are many groups of file infectors.

5. Nowadays number of viruses is about 55.000.

6. Other group is called parasitic or overwriting viruses.

7. Viruses also don't infect computer hardware such as monitors or computer chips; they only infect software.

8. Virus is a software designed and written to adversely affect your computer.

9. Viruses didn't spontaneously generate.

10. A malignant virus is one that is designed to do no real damage to your computer.

11. A benign virus might alter one or two of your programs so that it doesn't work, as it should.

12. The infected programs second of you system area.

13. In addition, Macintosh virus doesn't infect DOS - based computer software and vice versa.

14. Finally, viruses don't necessarily let you know that they are there - even after do something destructive.

15. In this case DOS wasn't find file with virus.

Task 7. Translate from Russian into Englis:

Задание 7. Переведите с русского языка на английский:

1. Что такое компьютерный вирус?

2. Вирус — это часть программного обеспечения, написанного для того, чтобы неблагоприятно влиять на ваш компьютер, изменяя его работу без вашего ведома и согласия.

3. Вирус имеет две отличительные функции: нанесение запланированного ущерба и самораспространение.

4. Существуют безвредные вирусы и вирусы, наносящие большой ущерб компьютеру.

5. Вирусы могут повредить данные, изменить программы, удалить файлы, стереть жесткий диск.

6. Вирусы не инфицируют файлы на пишущихся защищенных дисках.

7. В настоящее время вирусов около 55.000.

8. Появляются новые, неизвестные типы вирусов, которые становятся все сложнее классифицировать.

9. Есть 3 группы вирусов: 1) всепишущие, 2) вирусы-паразиты, 3) вирусы-компаньоны.

10. Установка антивирусных программ позволяет находить и удалять вирусы.

Task 8. Make the sentences negative and interrogative:

Задание 8. Преобразуйте следующие предложения в вопросительную и отрицательную форму:

1. A virus is a piece of software.

2. This is a significant number of viruses.

3. A malicious virus might alter one or more of your program.

4. Some viruses are programmed specifically to damage the data on your computer programs.

5. Computer viruses infect files on write-protected disks.

6. Number of viruses is about 55.000.

7. These are three groups of file infectors.

8. Viruses can copy itself into begin, middle or end of a file.

9. This is a subgroup of companion viruses path — companion viruses.

10. Virus copies itself in a file.