Ch-4
(Computer Virus)
Ex. 1,2 & 3
Ex.
4, 5 & 6
Ex. 4 Define
a. a. Worm:
–
Worm is a harmless virus that simply replicates itself. But in the long run, it
takes over all the resources of the computer system, and eventually the
computer becomes useless. Worms have the capacity to travel from system to
system very easily.
b. b. Trojan
Horse: – Trojan Horses virus comes as a friendly program (as a
game, application, etc.); however, it is very dangerous as it destroys all the
data on your system.
c. c. Rootkit:
–
Rootkit is a program that hides in a computer and allows someone from a remote
location to take full control of the computer.
d. d. Logic
bomb: – A logic bomb is a program, or portion of a program,
which lies dormant until a specific piece of program logic is activated. In
this way, a logic bomb is very analogous to a real-world land mine. The most
common activator for a logic bomb is a date.
e. e. Adware:
–
It is a program that displays an unwanted advertisement in a banner, popup
window on the web pages, email messages or on other internet services.
f. f. Spyware:
–
A program secretly collects the information about the user and then
communicates the same information to some outside source while the user is
online.
g. g. Virus
signature: – Antivirus programs use virus signature as
one of their techniques for detecting viruses. A virus signature also called a
virus definition is known specific pattern of virus code.
h. h. Virus
hoax: –Virus Hoax in an e-mail messages that warns user of a
non-existent virus or other Malware
Ex. 5
a. a. What is a computer virus?
Virus stand for Vital Information
Resource Under Seize. Viruses are programs which are creative deliberately to
damage critical information and data.
b. b. How does Christmas virus spread?
It
is an email worm that spreads via electronic mail as a small, executable file
with a variety of names and extensions. The worm is propagated by copying
itself onto local and networked drives, as well as emailing itself as an
attachment to any addresses.
c. c. What is a Malware?
Malware (short for malicious software) is a
term used for computer viruses, worms, Trojan horses, and rootkits. It is a
program that acts without a user’s knowledge and deliberately alters the
computer operations.
d. d. Name some antivirus software programs.
i.
Norton
Antivirus
ii.
Mcafee
iii.
Kaspersky
Antivirus
iv.
panda
Antivirus Pro
v.
F-Secure
Antivirus
vi.
AVG
Antivirus
vii.
TotalLav
viii.
Quick
Heal
e. e. Why do we use antivirus program?
An antivirus program protects a computer against virus,
identifying and removing any computer virus found in the memory, storage media,
or incoming files.
Ex. 6
a. a. Explain the different types of viruses.
Type of viruses are following: –
File Infector: This virus can cause irreversible damage to files by
permanently destroying the content.
Boot Sector Virus: this virus attaches itself to the boot sector of the
disk. This sector is read and loaded into the memory every time the disk is
booted. Evidently, this virus is also very dangerous.
Executable File Virus: This virus stores itself in an executable file
and infects other files each time the file is run.
Macro Virus: This virus infects files that are created using certain
applications or programs that contain macros.
b. b. What are the source of computer virus?
Email:
When
you open an e-email attachment that contains a virus, the virus spreads to your
computer. If you forward the attachment to other people, their computers will
also be affected.
Internet download: There is a lot of stuff to download from the
Internet. But if something in the stuff, you want to download, is infected by
virus, then the virus comes to your computer system.
Illegal Distribution of Software: If your computer is virus-infected and
you copy a software on CD to distribute to someone, the virus of your computer
might also get copied on the CD. The person, who installs this software on his
computer, unknowingly gets his computer infected by the virus.
c. c. What are the symptoms of virus?
Symptoms of Viruses are following: –
i.
Computer runs
much slower than usual.
ii.
Memory of
computer is less than expected.
iii.
Files
become corrupted.
iv.
Screen
displays unusual message or image.
v.
Music or
unusual sound plays randomly.
vi.
Existing
programs and files disappear.
vii.
Programs
or files do not work properly.
viii.
System
properties change.
d. d. What are the effects of virus on computer?
Effects of viruses are following: –
i.
It can
damage of rename the important files.
ii.
It can
damage or destroy the operating system.
iii.
It can
decrease the speed of the computer.
iv.
It can
reduce the memory or hard disk space.
v.
It can
infect boot records.
vi.
It can
infect executable files.
e.
e. What is an e-mail virus? How
does it spread?
Email
viruses are spread by the files attached to e-mail messages. As e-mail
attachments have become more common, the number of e-mail viruses has also
increased. You cannot get an e-mail virus from a message that contains only
text.
When you open an e-mail attachment that contains a virus, the virus spreads to
your computer. If you forward the attachment to other people, their computer
will also be affected when they open the attachment.
f. f. How does Ransomware virus
spread?
Ransomware can enter your computer through an email attachment or through your
web browser if you happen to visit a website that is infected with this type of
virus. It can also access your PC via your network. If your computer has been
infected with ransomware, then you most probably won’t be able to access your
computer.
g. g. Write any five precautions that should be taken to prevent computer
virus.
i.
Do not start a computer with removable
media inserted in the drives or plugged in the ports.
ii.
Never open an e-mail attachment, unless
you are expecting the attachment, and it is from a trusted source.
iii.
If a friend unexpectedly sends you a
message with an attachment, do not assume that the attachment is safe.
iv.
Install an antivirus program on all your
computers. Update the software and the virus signature files regularly.
v.
Stay informed about new virus alerts and
virus hoaxes.
vi.
Scan all downloaded programs for viruses
and other malware.
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