NCERT Textbook - Security Threats and Safety , Information & Computer Technology Class 9 | Information & Computer Technology (Class 9) - Notes & Video PDF Download

 Page 1


96
Information and Computer Technology
Chapter 6
Security Threats and Safety 
Measures
Learning Objectives 
By the end of this chapter, learner will be able to:
• Name	 the	 diff er en t	 kinds	 of	 softw ar e	 licensing	 a v ailable
• 	 Diff er en tia t e	 be tw een	 fr ee w ar e	 and	 open	 sour ce	 softw ar e
• 	 St a t e	 ho w	 the	 use	 of	 shar e w ar e	 softw ar e	 is	 diff er en t	 fr om	 tha t	 of	 fr ee w ar e	 softw ar e
• 	 Diff er en tia t e	 be tw een	 c op yrigh t	 and	 licensing
• 	 De fine	 cyber e thics,	 cyber sa f e ty	 and	 cyber security
• 	 St a t e	 the	 purpose	 of	 c ookies
• 	 T abula t e	 the	 diff er en t	 phases	 of	 cyber	 e thics	 e v olution
• 	 Lis t	 pr ec autions	 tha t	 c an	 be	 t ak en	 t o	 ensur e	 cyber	 sa f e ty
• 	 Iden tif y	 the	 diff er en t	 kinds	 of	 thr ea ts	 t o	 	 cyber	 security
• 	 St a t e	 e thic al	 beha viour	 t o	 be	 f ollo w ed	 as	 a	 cyber	 citiz en
• Iden tif y	 the	 diff er en t	 c a t eg ories	 of	 cyber	 crime
IntroduCtIon
With the wide spread use of internet, networks and computers have 
become increasingly susceptible to threats. These threats destroy data 
as well the programs that computers use.  The objective of these 
threats is to destroy the data and to steal the vital information stored 
in computers. This information is used by the attackers for their 
benefit. We occasionally hear about the data theft from credit card 
companies or banks, which lead to major financial losses. Also sometimes individual 
users are fooled in to giving their personal and sensitive information such as passwords 
or bank data leading to financial loss. This chapter shows various threats that computers 
and networks face.
1. vIruSeS
A computer virus is a program usually hidden within another simple program. It produces 
copies of itself and inserts them into other programs or files, in turn destroying the data 
and performing other malicious actions. Computer viruses are never naturally occurring; 
they are always man-made. Once created and released, however, their spread does not 
Page 2


96
Information and Computer Technology
Chapter 6
Security Threats and Safety 
Measures
Learning Objectives 
By the end of this chapter, learner will be able to:
• Name	 the	 diff er en t	 kinds	 of	 softw ar e	 licensing	 a v ailable
• 	 Diff er en tia t e	 be tw een	 fr ee w ar e	 and	 open	 sour ce	 softw ar e
• 	 St a t e	 ho w	 the	 use	 of	 shar e w ar e	 softw ar e	 is	 diff er en t	 fr om	 tha t	 of	 fr ee w ar e	 softw ar e
• 	 Diff er en tia t e	 be tw een	 c op yrigh t	 and	 licensing
• 	 De fine	 cyber e thics,	 cyber sa f e ty	 and	 cyber security
• 	 St a t e	 the	 purpose	 of	 c ookies
• 	 T abula t e	 the	 diff er en t	 phases	 of	 cyber	 e thics	 e v olution
• 	 Lis t	 pr ec autions	 tha t	 c an	 be	 t ak en	 t o	 ensur e	 cyber	 sa f e ty
• 	 Iden tif y	 the	 diff er en t	 kinds	 of	 thr ea ts	 t o	 	 cyber	 security
• 	 St a t e	 e thic al	 beha viour	 t o	 be	 f ollo w ed	 as	 a	 cyber	 citiz en
• Iden tif y	 the	 diff er en t	 c a t eg ories	 of	 cyber	 crime
IntroduCtIon
With the wide spread use of internet, networks and computers have 
become increasingly susceptible to threats. These threats destroy data 
as well the programs that computers use.  The objective of these 
threats is to destroy the data and to steal the vital information stored 
in computers. This information is used by the attackers for their 
benefit. We occasionally hear about the data theft from credit card 
companies or banks, which lead to major financial losses. Also sometimes individual 
users are fooled in to giving their personal and sensitive information such as passwords 
or bank data leading to financial loss. This chapter shows various threats that computers 
and networks face.
1. vIruSeS
A computer virus is a program usually hidden within another simple program. It produces 
copies of itself and inserts them into other programs or files, in turn destroying the data 
and performing other malicious actions. Computer viruses are never naturally occurring; 
they are always man-made. Once created and released, however, their spread does not 
Security Threats and Safety Measures
97
remain directly under our control. While developing the viruses, programmers have 
specific target in mind such as data theft or destruction of software, which runs the 
computers. The virus can be transferred hidden in files, programs or even in disks. The 
viruses can be of different kind but a common virus is macro virus, which is discussed 
in detail here. 
1.1 Macro v iruses
A simple macro is series of programming steps that are stored in a single location. Macro 
allows automation of many actions with only a single keystroke. These can be embedded 
in the program files. Many programs, such as Word and excel allow you to record a series 
of keystrokes and menu selections and then save them to a file. This helps eliminate 
doing the same action several times increasing efficiency. Macro viruses created with the 
intention of fooling the user can deceive them in sharing confidential information. This 
information can be used by the Macro to damage the computer data or software. The 
virus using macro files are most popular as they are:
 ? Easy to write.
 ? Can infect more people faster as they exchange documents and data frequently
 ? Can easily infect any computer capable of running Office and Internet 
Macro viruses can corrupt data, create new files, move text, flash colors, insert pictures, 
send files across the Internet, and format hard drives. Macro viruses are increasingly used 
as transport mechanisms to drop off even nastier bugs. Macro viruses modify registries, 
forward copies of it through emails, look for passwords, copy documents, and infect other 
programs. Macro viruses can do a lot of different damage in a lot of different ways.
Example of macro Virus is Wazzo, W97M etc.
2. WorMS
Worms are very similar to viruses in the manner that they are computer programs that 
replicate copies of themselves (usually to other computer systems via network connections). 
Viruses often, but not always, contain some functionality that will interfere with the normal 
use of a computer or a program. Unlike viruses, however, worms exist as separate entities; 
they do not attach themselves to other files or programs. Because of their similarity to 
viruses, worms are also often referred to as viruses. Some examples of the worst Worms 
that impacted the web are as follows:
 1. Jerusalem is one of the earliest worms that spread in 1987. It is also one of the most 
commonly known viruses. It used to delete files that were executed on each Friday 
the 13th. It was first detected in the city of Jerusalem.
Page 3


96
Information and Computer Technology
Chapter 6
Security Threats and Safety 
Measures
Learning Objectives 
By the end of this chapter, learner will be able to:
• Name	 the	 diff er en t	 kinds	 of	 softw ar e	 licensing	 a v ailable
• 	 Diff er en tia t e	 be tw een	 fr ee w ar e	 and	 open	 sour ce	 softw ar e
• 	 St a t e	 ho w	 the	 use	 of	 shar e w ar e	 softw ar e	 is	 diff er en t	 fr om	 tha t	 of	 fr ee w ar e	 softw ar e
• 	 Diff er en tia t e	 be tw een	 c op yrigh t	 and	 licensing
• 	 De fine	 cyber e thics,	 cyber sa f e ty	 and	 cyber security
• 	 St a t e	 the	 purpose	 of	 c ookies
• 	 T abula t e	 the	 diff er en t	 phases	 of	 cyber	 e thics	 e v olution
• 	 Lis t	 pr ec autions	 tha t	 c an	 be	 t ak en	 t o	 ensur e	 cyber	 sa f e ty
• 	 Iden tif y	 the	 diff er en t	 kinds	 of	 thr ea ts	 t o	 	 cyber	 security
• 	 St a t e	 e thic al	 beha viour	 t o	 be	 f ollo w ed	 as	 a	 cyber	 citiz en
• Iden tif y	 the	 diff er en t	 c a t eg ories	 of	 cyber	 crime
IntroduCtIon
With the wide spread use of internet, networks and computers have 
become increasingly susceptible to threats. These threats destroy data 
as well the programs that computers use.  The objective of these 
threats is to destroy the data and to steal the vital information stored 
in computers. This information is used by the attackers for their 
benefit. We occasionally hear about the data theft from credit card 
companies or banks, which lead to major financial losses. Also sometimes individual 
users are fooled in to giving their personal and sensitive information such as passwords 
or bank data leading to financial loss. This chapter shows various threats that computers 
and networks face.
1. vIruSeS
A computer virus is a program usually hidden within another simple program. It produces 
copies of itself and inserts them into other programs or files, in turn destroying the data 
and performing other malicious actions. Computer viruses are never naturally occurring; 
they are always man-made. Once created and released, however, their spread does not 
Security Threats and Safety Measures
97
remain directly under our control. While developing the viruses, programmers have 
specific target in mind such as data theft or destruction of software, which runs the 
computers. The virus can be transferred hidden in files, programs or even in disks. The 
viruses can be of different kind but a common virus is macro virus, which is discussed 
in detail here. 
1.1 Macro v iruses
A simple macro is series of programming steps that are stored in a single location. Macro 
allows automation of many actions with only a single keystroke. These can be embedded 
in the program files. Many programs, such as Word and excel allow you to record a series 
of keystrokes and menu selections and then save them to a file. This helps eliminate 
doing the same action several times increasing efficiency. Macro viruses created with the 
intention of fooling the user can deceive them in sharing confidential information. This 
information can be used by the Macro to damage the computer data or software. The 
virus using macro files are most popular as they are:
 ? Easy to write.
 ? Can infect more people faster as they exchange documents and data frequently
 ? Can easily infect any computer capable of running Office and Internet 
Macro viruses can corrupt data, create new files, move text, flash colors, insert pictures, 
send files across the Internet, and format hard drives. Macro viruses are increasingly used 
as transport mechanisms to drop off even nastier bugs. Macro viruses modify registries, 
forward copies of it through emails, look for passwords, copy documents, and infect other 
programs. Macro viruses can do a lot of different damage in a lot of different ways.
Example of macro Virus is Wazzo, W97M etc.
2. WorMS
Worms are very similar to viruses in the manner that they are computer programs that 
replicate copies of themselves (usually to other computer systems via network connections). 
Viruses often, but not always, contain some functionality that will interfere with the normal 
use of a computer or a program. Unlike viruses, however, worms exist as separate entities; 
they do not attach themselves to other files or programs. Because of their similarity to 
viruses, worms are also often referred to as viruses. Some examples of the worst Worms 
that impacted the web are as follows:
 1. Jerusalem is one of the earliest worms that spread in 1987. It is also one of the most 
commonly known viruses. It used to delete files that were executed on each Friday 
the 13th. It was first detected in the city of Jerusalem.
98
Information and Computer Technology
 2. In 1991, thousands of machines running MS-DOS were hit by a new worm, 
Michelangelo. The virus would overwrite the hard disk or change the master boot 
record of infected hosts.
 3. In 2007 Storm Worm hit the computers. Once hit, your machine becomes part of a 
large botnet which performs automated tasks that range from gathering data on the 
host machine, to sending infected emails to others. About 1.2 billion emails were 
sent from the infected computers propagating infection.
Since Worms spread mostly through the email attachments, the best ways to avoid them 
is using caution in opening emails. If the email is from an unidentified source, it is always 
best to delete it. Most of the time worms attach themselves to email. Even the sender of 
email does not recognize what they have forwarded, as emails are sent automatically using 
all contact information in the user’s profile.
3. trojan HorSeS
A Trojan horse is a program that claims to rid your computer of viruses but instead 
introduces viruses into the system. Since they look like sincere programs they are referred 
as Trojan like the Trojan horse of Greek mythology. The Trojan program does not attach 
itself to the files like a virus nor replicate itself like a worm but it does provide unauthorized 
access to user’s computer.  
They are mostly spread through internet downloads and online gaming programs. They 
mostly affect the targeted computers. The trojan program prompts you to do the normal 
functions such as inputting your email address or profile name. Y ou do so, not knowing 
that, you have provided access to the malicious software. This software is capable of taking 
over the functionality of your computer. An infected computer will begin to operate slowly 
and will exhibit pop-ups from time to time. Eventually the computer will cease to operate, 
or crash. 
The best way to avoid the Trojans is to adopt safe download practices. If you are not sure of 
the website safety, then it is probably best not to download any program from that source.
An example of the Trojan horse was “I love you” which infected several computers in USA 
and Asia, completely damaging the data of millions of computers
4. SPyWare
A Spyware as the name suggest is a program used to spy on the computer system. This 
program will try to get all the confidential and sensitive information such as your bank 
Page 4


96
Information and Computer Technology
Chapter 6
Security Threats and Safety 
Measures
Learning Objectives 
By the end of this chapter, learner will be able to:
• Name	 the	 diff er en t	 kinds	 of	 softw ar e	 licensing	 a v ailable
• 	 Diff er en tia t e	 be tw een	 fr ee w ar e	 and	 open	 sour ce	 softw ar e
• 	 St a t e	 ho w	 the	 use	 of	 shar e w ar e	 softw ar e	 is	 diff er en t	 fr om	 tha t	 of	 fr ee w ar e	 softw ar e
• 	 Diff er en tia t e	 be tw een	 c op yrigh t	 and	 licensing
• 	 De fine	 cyber e thics,	 cyber sa f e ty	 and	 cyber security
• 	 St a t e	 the	 purpose	 of	 c ookies
• 	 T abula t e	 the	 diff er en t	 phases	 of	 cyber	 e thics	 e v olution
• 	 Lis t	 pr ec autions	 tha t	 c an	 be	 t ak en	 t o	 ensur e	 cyber	 sa f e ty
• 	 Iden tif y	 the	 diff er en t	 kinds	 of	 thr ea ts	 t o	 	 cyber	 security
• 	 St a t e	 e thic al	 beha viour	 t o	 be	 f ollo w ed	 as	 a	 cyber	 citiz en
• Iden tif y	 the	 diff er en t	 c a t eg ories	 of	 cyber	 crime
IntroduCtIon
With the wide spread use of internet, networks and computers have 
become increasingly susceptible to threats. These threats destroy data 
as well the programs that computers use.  The objective of these 
threats is to destroy the data and to steal the vital information stored 
in computers. This information is used by the attackers for their 
benefit. We occasionally hear about the data theft from credit card 
companies or banks, which lead to major financial losses. Also sometimes individual 
users are fooled in to giving their personal and sensitive information such as passwords 
or bank data leading to financial loss. This chapter shows various threats that computers 
and networks face.
1. vIruSeS
A computer virus is a program usually hidden within another simple program. It produces 
copies of itself and inserts them into other programs or files, in turn destroying the data 
and performing other malicious actions. Computer viruses are never naturally occurring; 
they are always man-made. Once created and released, however, their spread does not 
Security Threats and Safety Measures
97
remain directly under our control. While developing the viruses, programmers have 
specific target in mind such as data theft or destruction of software, which runs the 
computers. The virus can be transferred hidden in files, programs or even in disks. The 
viruses can be of different kind but a common virus is macro virus, which is discussed 
in detail here. 
1.1 Macro v iruses
A simple macro is series of programming steps that are stored in a single location. Macro 
allows automation of many actions with only a single keystroke. These can be embedded 
in the program files. Many programs, such as Word and excel allow you to record a series 
of keystrokes and menu selections and then save them to a file. This helps eliminate 
doing the same action several times increasing efficiency. Macro viruses created with the 
intention of fooling the user can deceive them in sharing confidential information. This 
information can be used by the Macro to damage the computer data or software. The 
virus using macro files are most popular as they are:
 ? Easy to write.
 ? Can infect more people faster as they exchange documents and data frequently
 ? Can easily infect any computer capable of running Office and Internet 
Macro viruses can corrupt data, create new files, move text, flash colors, insert pictures, 
send files across the Internet, and format hard drives. Macro viruses are increasingly used 
as transport mechanisms to drop off even nastier bugs. Macro viruses modify registries, 
forward copies of it through emails, look for passwords, copy documents, and infect other 
programs. Macro viruses can do a lot of different damage in a lot of different ways.
Example of macro Virus is Wazzo, W97M etc.
2. WorMS
Worms are very similar to viruses in the manner that they are computer programs that 
replicate copies of themselves (usually to other computer systems via network connections). 
Viruses often, but not always, contain some functionality that will interfere with the normal 
use of a computer or a program. Unlike viruses, however, worms exist as separate entities; 
they do not attach themselves to other files or programs. Because of their similarity to 
viruses, worms are also often referred to as viruses. Some examples of the worst Worms 
that impacted the web are as follows:
 1. Jerusalem is one of the earliest worms that spread in 1987. It is also one of the most 
commonly known viruses. It used to delete files that were executed on each Friday 
the 13th. It was first detected in the city of Jerusalem.
98
Information and Computer Technology
 2. In 1991, thousands of machines running MS-DOS were hit by a new worm, 
Michelangelo. The virus would overwrite the hard disk or change the master boot 
record of infected hosts.
 3. In 2007 Storm Worm hit the computers. Once hit, your machine becomes part of a 
large botnet which performs automated tasks that range from gathering data on the 
host machine, to sending infected emails to others. About 1.2 billion emails were 
sent from the infected computers propagating infection.
Since Worms spread mostly through the email attachments, the best ways to avoid them 
is using caution in opening emails. If the email is from an unidentified source, it is always 
best to delete it. Most of the time worms attach themselves to email. Even the sender of 
email does not recognize what they have forwarded, as emails are sent automatically using 
all contact information in the user’s profile.
3. trojan HorSeS
A Trojan horse is a program that claims to rid your computer of viruses but instead 
introduces viruses into the system. Since they look like sincere programs they are referred 
as Trojan like the Trojan horse of Greek mythology. The Trojan program does not attach 
itself to the files like a virus nor replicate itself like a worm but it does provide unauthorized 
access to user’s computer.  
They are mostly spread through internet downloads and online gaming programs. They 
mostly affect the targeted computers. The trojan program prompts you to do the normal 
functions such as inputting your email address or profile name. Y ou do so, not knowing 
that, you have provided access to the malicious software. This software is capable of taking 
over the functionality of your computer. An infected computer will begin to operate slowly 
and will exhibit pop-ups from time to time. Eventually the computer will cease to operate, 
or crash. 
The best way to avoid the Trojans is to adopt safe download practices. If you are not sure of 
the website safety, then it is probably best not to download any program from that source.
An example of the Trojan horse was “I love you” which infected several computers in USA 
and Asia, completely damaging the data of millions of computers
4. SPyWare
A Spyware as the name suggest is a program used to spy on the computer system. This 
program will try to get all the confidential and sensitive information such as your bank 
Security Threats and Safety Measures
99
account numbers, passwords etc. Then this confidential data is misused to access user’s 
accounts. Spyware can also change the configuration of your computer, generally without 
obtaining your consent first.
There are a number of ways Spyware or other unwanted software can get on to computer. 
A common trick is to covertly install the software during the installation of other software 
that is being downloaded such as music or video or a file-sharing program.
Once installed, the Spyware monitors user activity on the Internet and transmits that 
information in the background to someone else. Spyware can also gather information 
about e-mail addresses and even passwords and credit card numbers.
SpyWare sends information back to the spy ware’s home base via the user’s Internet 
connection, thus it eats user’s internet bandwidth. SpyWare applications running in the 
background can lead to system crashes or general system instability as they use memory 
and system resources of the user’s computer.
SpyWare have the ability to monitor keystrokes, scan files on the hard drive, snoop other 
applications, such as chat programs or word processors. It also installs other SpyWare 
programs, read cookies, change the default home page on the Web browser. While doing 
so, it consistently relays this information back to the SpyWare author who will either sell 
the information to another party or use it for advertising/marketing purposes.
Some of the common Spywares are CoolWebSearch, Internet optimizer and Zango
5. Mal Ware
Malware is short for “malicious software. ” Malware is any kind of unwanted software that 
is installed without your adequate consent. The intent of the malware is to damage the 
data or functionality of the computer or network. In fact all the threats mentioned above 
such as virus, Trojans etc are examples of Malware.
6. SPaMS
The term “spam” refers to unsolicited commercial email (UCE) or unsolicited bulk email 
(UBE). It is flooding the Internet with many copies of the same message, in an attempt 
to force the message on people who would not otherwise choose to receive it. It is also 
referred as junk email. Unsolicited email mostly contains advertisements for services or 
products. However most of the spams are from marketers or user who are trying to deceive 
the users. The most commonly seen spam includes the following:
Page 5


96
Information and Computer Technology
Chapter 6
Security Threats and Safety 
Measures
Learning Objectives 
By the end of this chapter, learner will be able to:
• Name	 the	 diff er en t	 kinds	 of	 softw ar e	 licensing	 a v ailable
• 	 Diff er en tia t e	 be tw een	 fr ee w ar e	 and	 open	 sour ce	 softw ar e
• 	 St a t e	 ho w	 the	 use	 of	 shar e w ar e	 softw ar e	 is	 diff er en t	 fr om	 tha t	 of	 fr ee w ar e	 softw ar e
• 	 Diff er en tia t e	 be tw een	 c op yrigh t	 and	 licensing
• 	 De fine	 cyber e thics,	 cyber sa f e ty	 and	 cyber security
• 	 St a t e	 the	 purpose	 of	 c ookies
• 	 T abula t e	 the	 diff er en t	 phases	 of	 cyber	 e thics	 e v olution
• 	 Lis t	 pr ec autions	 tha t	 c an	 be	 t ak en	 t o	 ensur e	 cyber	 sa f e ty
• 	 Iden tif y	 the	 diff er en t	 kinds	 of	 thr ea ts	 t o	 	 cyber	 security
• 	 St a t e	 e thic al	 beha viour	 t o	 be	 f ollo w ed	 as	 a	 cyber	 citiz en
• Iden tif y	 the	 diff er en t	 c a t eg ories	 of	 cyber	 crime
IntroduCtIon
With the wide spread use of internet, networks and computers have 
become increasingly susceptible to threats. These threats destroy data 
as well the programs that computers use.  The objective of these 
threats is to destroy the data and to steal the vital information stored 
in computers. This information is used by the attackers for their 
benefit. We occasionally hear about the data theft from credit card 
companies or banks, which lead to major financial losses. Also sometimes individual 
users are fooled in to giving their personal and sensitive information such as passwords 
or bank data leading to financial loss. This chapter shows various threats that computers 
and networks face.
1. vIruSeS
A computer virus is a program usually hidden within another simple program. It produces 
copies of itself and inserts them into other programs or files, in turn destroying the data 
and performing other malicious actions. Computer viruses are never naturally occurring; 
they are always man-made. Once created and released, however, their spread does not 
Security Threats and Safety Measures
97
remain directly under our control. While developing the viruses, programmers have 
specific target in mind such as data theft or destruction of software, which runs the 
computers. The virus can be transferred hidden in files, programs or even in disks. The 
viruses can be of different kind but a common virus is macro virus, which is discussed 
in detail here. 
1.1 Macro v iruses
A simple macro is series of programming steps that are stored in a single location. Macro 
allows automation of many actions with only a single keystroke. These can be embedded 
in the program files. Many programs, such as Word and excel allow you to record a series 
of keystrokes and menu selections and then save them to a file. This helps eliminate 
doing the same action several times increasing efficiency. Macro viruses created with the 
intention of fooling the user can deceive them in sharing confidential information. This 
information can be used by the Macro to damage the computer data or software. The 
virus using macro files are most popular as they are:
 ? Easy to write.
 ? Can infect more people faster as they exchange documents and data frequently
 ? Can easily infect any computer capable of running Office and Internet 
Macro viruses can corrupt data, create new files, move text, flash colors, insert pictures, 
send files across the Internet, and format hard drives. Macro viruses are increasingly used 
as transport mechanisms to drop off even nastier bugs. Macro viruses modify registries, 
forward copies of it through emails, look for passwords, copy documents, and infect other 
programs. Macro viruses can do a lot of different damage in a lot of different ways.
Example of macro Virus is Wazzo, W97M etc.
2. WorMS
Worms are very similar to viruses in the manner that they are computer programs that 
replicate copies of themselves (usually to other computer systems via network connections). 
Viruses often, but not always, contain some functionality that will interfere with the normal 
use of a computer or a program. Unlike viruses, however, worms exist as separate entities; 
they do not attach themselves to other files or programs. Because of their similarity to 
viruses, worms are also often referred to as viruses. Some examples of the worst Worms 
that impacted the web are as follows:
 1. Jerusalem is one of the earliest worms that spread in 1987. It is also one of the most 
commonly known viruses. It used to delete files that were executed on each Friday 
the 13th. It was first detected in the city of Jerusalem.
98
Information and Computer Technology
 2. In 1991, thousands of machines running MS-DOS were hit by a new worm, 
Michelangelo. The virus would overwrite the hard disk or change the master boot 
record of infected hosts.
 3. In 2007 Storm Worm hit the computers. Once hit, your machine becomes part of a 
large botnet which performs automated tasks that range from gathering data on the 
host machine, to sending infected emails to others. About 1.2 billion emails were 
sent from the infected computers propagating infection.
Since Worms spread mostly through the email attachments, the best ways to avoid them 
is using caution in opening emails. If the email is from an unidentified source, it is always 
best to delete it. Most of the time worms attach themselves to email. Even the sender of 
email does not recognize what they have forwarded, as emails are sent automatically using 
all contact information in the user’s profile.
3. trojan HorSeS
A Trojan horse is a program that claims to rid your computer of viruses but instead 
introduces viruses into the system. Since they look like sincere programs they are referred 
as Trojan like the Trojan horse of Greek mythology. The Trojan program does not attach 
itself to the files like a virus nor replicate itself like a worm but it does provide unauthorized 
access to user’s computer.  
They are mostly spread through internet downloads and online gaming programs. They 
mostly affect the targeted computers. The trojan program prompts you to do the normal 
functions such as inputting your email address or profile name. Y ou do so, not knowing 
that, you have provided access to the malicious software. This software is capable of taking 
over the functionality of your computer. An infected computer will begin to operate slowly 
and will exhibit pop-ups from time to time. Eventually the computer will cease to operate, 
or crash. 
The best way to avoid the Trojans is to adopt safe download practices. If you are not sure of 
the website safety, then it is probably best not to download any program from that source.
An example of the Trojan horse was “I love you” which infected several computers in USA 
and Asia, completely damaging the data of millions of computers
4. SPyWare
A Spyware as the name suggest is a program used to spy on the computer system. This 
program will try to get all the confidential and sensitive information such as your bank 
Security Threats and Safety Measures
99
account numbers, passwords etc. Then this confidential data is misused to access user’s 
accounts. Spyware can also change the configuration of your computer, generally without 
obtaining your consent first.
There are a number of ways Spyware or other unwanted software can get on to computer. 
A common trick is to covertly install the software during the installation of other software 
that is being downloaded such as music or video or a file-sharing program.
Once installed, the Spyware monitors user activity on the Internet and transmits that 
information in the background to someone else. Spyware can also gather information 
about e-mail addresses and even passwords and credit card numbers.
SpyWare sends information back to the spy ware’s home base via the user’s Internet 
connection, thus it eats user’s internet bandwidth. SpyWare applications running in the 
background can lead to system crashes or general system instability as they use memory 
and system resources of the user’s computer.
SpyWare have the ability to monitor keystrokes, scan files on the hard drive, snoop other 
applications, such as chat programs or word processors. It also installs other SpyWare 
programs, read cookies, change the default home page on the Web browser. While doing 
so, it consistently relays this information back to the SpyWare author who will either sell 
the information to another party or use it for advertising/marketing purposes.
Some of the common Spywares are CoolWebSearch, Internet optimizer and Zango
5. Mal Ware
Malware is short for “malicious software. ” Malware is any kind of unwanted software that 
is installed without your adequate consent. The intent of the malware is to damage the 
data or functionality of the computer or network. In fact all the threats mentioned above 
such as virus, Trojans etc are examples of Malware.
6. SPaMS
The term “spam” refers to unsolicited commercial email (UCE) or unsolicited bulk email 
(UBE). It is flooding the Internet with many copies of the same message, in an attempt 
to force the message on people who would not otherwise choose to receive it. It is also 
referred as junk email. Unsolicited email mostly contains advertisements for services or 
products. However most of the spams are from marketers or user who are trying to deceive 
the users. The most commonly seen spam includes the following:
100
Information and Computer Technology
 ? Phishing scams, a very popular and dangerous form of email fraud
 ? Foreign bank scams or advance fee fraud schemes
 ? Other “Get Rich Quick” or “Make Money Fast” (MMF) schemes
 ? Quack health products and remedies
Spam emails is not only unwanted, it clogs your email accounts and uses unnecessary 
server space. This creates burden on servers in the businesses. Since Internet is a public 
platform, it is never possible to completely stop the Spam email. However precaution 
can be taken while looking at an unknown email addresses. Most of the email  hosts can 
identify such users and help filter them.
Spam costs the sender very little to send -- most of the costs are paid for by the recipient 
or the carriers rather than by the sender. It is because of these additional costs that most 
of the hosts are very keen that users use spam filters as well as report spams so they can 
be stopped.
7. HaCkerS and CraCkerS
Hackers and crackers are the software programmers who use dubious 
ways to get control over your computer and systems. The intent of 
both hackers and crackers is to gain control over your computer so 
that they can get the sensitive confidential information. They then use 
this information against you by stealing money, personal data, pictures, 
bank details and government military information, so on and so forth. 
This information can either be sold for money or hackers access account 
themselves to rob you directly. Originally hackers were the gifted programmers who gain 
access to the systems or network to show case the security loopholes to the administrators. 
Later the term cracker was coined for such activist who had intentions of doing malicious 
activities. Crackers have an end goal of destroying data and network for personal monetary 
gains.
8. antI vIruS toolS
Anti Virus tools are the software programs that help us detect the virus in emails or files 
and hence protect our computers. These tools can detect virus, worms, Trojans as well as 
spyware and adware.  They block us from visiting unsafe websites, and also downloading 
unsafe programs from such websites. They protect us from identity thefts and threats 
from phishing websites. There are several commercial antivirus softwares available such 
as Norton, Mcafee, K7, Quickheal etc.