Class 7

Computer Viruses – Types, Symptoms, and Prevention

Objective Type Questions

A. Fill in the blanks with the correct words.

  1. Most viruses stay active until you turn off the computer.
  2. A computer virus may or may not be destructive.
  3. A computer virus cannot infect files on write-protected discs.
  4. A computer infected with a computer virus may run slower than normal.
  5. Program viruses infect files that have extensions .com, .exe, etc.
  6. A macro is a set of commands written by the user to be executed later.
  7. Malware is short for malicious software.
  8. A trojan horse is a program that appears useful, but is actually programmed to pass on the user’s data to someone else.

B. Write T for the true statement and F for the false one. Correct the false statement(s).

  1. An antivirus program should run in the background at all times. (T)
  2. Once you purchase an antivirus software, you need not update it for one year. (F) (We need to update it regularly).
  3. You should delete spam mails without reading them. (T)
  4. You should restrict access to your computer, both offline and online. (T)
  5. Malware does not harm your computer. (F) (Malware is harmful for the computer)
  6. Generally, boot viruses are considered more dangerous than program viruses. (T)
  7. Viruses can infect the keyboard. (F) (Viruses cannot infect the keyboard)
  8. Viruses cannot spread from one computer to another. (F) (Viruses can spread from one computer to another)

C. Choose the correct option.

  1. A virus may be capable of:
    a) Infecting executable files.
    b) Infecting disks by attaching itself to special programs on the hard disk.
    c) Both a and b
    d) None of the above
  2. Which of the following are the signs of a virus attack?
    a) The computer runs slower than normal.
    b) There is a change in file size.
    c) The computer restarts on its own.
    d) All of the above.
  3. A computer virus can spread through:
    a) E-mails
    b) Pen drives
    c) Both a and b
    d) None of these
  4. Program viruses infect files that have the extension:
    a) .COM
    b) .EXE
    c) .SYS
    d) All of these
  5. Which of the following is a boot virus?
    a) Michelangelo
    b) Sunday
    c) Acid Rain
    d) None of these
  6. Which of the following are infected by a macro virus?
    a) .exe files
    b) Boot records
    c) Data files
    d) None of these
  7. ________ refers to computer programs that secretly gather information about the user and relay it to other interested parties.
    a) Worm
    b) Spyware
    c) Virus
    d) None of these
  8. ________ refers to unsolicited mail.
    a) Spam
    b) E-mail
    c) Mail
    d) None of these

Descriptive Type Questions

D. Answer the following.

  1. Name the type of virus that infects data files.
    Macro viruses infect data files.
  2. What is the name given to a database of viruses that an antivirus software scans for?
    Virus definitions is the name given to a database of virus that an antivirus software scans for.
  3. Define a virus. How can it harm your computer?
    Virus is a software program that has the ability to make copies of itself and to attach itself to other applications or files.
    It can harm our computer in the following ways:
    a) by infecting executable program files and data files
    b) by infecting the boot record in the hard disk
    c) by consuming large amount of memory
    d) by passing the user’s data to someone else
    e) by secretly gathering information about the user.
  4. Mention any three precautions you should take for protecting your computer from virus infections.
    Following are the three precautions that we should take for protecting our computer from virus infections:
    a) We should restrict access to our computer, both offline and online.
    b) We should allow only trustworthy users to use the computer.
    c) We should install and use an antivirus and keep it updated.
  5. How does a virus spread from one computer to another?
    Viruses spread from one computer to another through e-mails, pen drives, or other sources.

Extra Questions

State whether True or False:

  1. Viruses run on computer systems without the user’s knowledge. (TRUE)
  2. Viruses can also infect new files created on the infected computer. (TRUE)
  3. A trojan horse may also delete important system files. (TRUE)
  4. A trojan horse do not reproduce. (TRUE)
  5. Whenever a computer system starts up, the antivirus software starts automatically. (TRUE)
  6. Running more than one antivirus program on a computer may negatively affect the performance of the computer. (TRUE)

Fill in the blanks:

  1. The startup area or the master boot record is the first sector of the computer hard drive.
  2. Commwarrior-A was the first known cell phone virus. It appeared in March 2005.
  3. Elk Cloner was a computer virus that attached itself to Apple II computers.
  4. A worm is a program capable of reproducing and spreading itself to another computer system, usually by means of a computer network.
  5. Malware refers to any program that infiltrates and harms a computer without the user’s consent.
  6. Since no security method is perfect, it is important to backup your files regularly.
  7. Boot viruses infect the boot records of hard disks and floppy discs.

Answer the following:

  1. Write some of the symptoms of virus attack.
    Following are some of the symptoms:
    a) Computer runs slower than normal.
    b) Screen distortion.
    c) Unable to open files.
    d) Data and programs are corrupted or damaged.
    e) Applications take longer to load.
    f) Unusual error messages appear on the screen.
    g) Sudden change in file size.
    h) Having more files in hard disk than it had earlier.
    i) The computer often stops responding.
    j) The computer restarts on its own.
    k) Seeing distorted menus and dialog boxes.
  2. Give a few examples of program viruses.
    Acid Rain, Alien.298, Amoeba.A, Crazy.A, Umbrella.3173, Sunday, Cascade.
  3. Give a few examples of boot viruses.
    Danish Boot, Devil.941, Eek (b), Disk Killer, Michelangelo, Stoned virus.
  4. Give a few examples of macro viruses.
    Melissa, Concept, Nuclear.
  5. Give a few examples of trojan horse.
    Netbus, SubSeven, Beast, Zeus.
  6. Give a few examples of worms.
    CodeRed, Sircam, ILOVEYOU.
  7. Give a few examples of anti-spyware programs.
    AdAware SE, Windows Defender.
  8. How can we avoid spam?
    We can avoid spam in the following ways:
    a) We shouldn’t give e-mail addresses to unknown people.
    b) We should use a spam filter.
    c) We should delete spams without reading them.
  9. What is an antivirus?
    Antivirus software refers to applications designed to detect and remove viruses from computer systems.
  10. Name some popular antivirus programs.
    McAfee VirusScan, Norton AntiVirus, Kaspersky AntiVirus, Quick Heal Total Security, Microsoft Security Essentials.
  11. Name a few free antivirus programs.
    AVG, Avast, Microsoft Security Essentials.
  12. What is a firewall?
    A firewall is a software program that helps keep out hackers, viruses, and worms that try to infect our computer over the Internet.

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