~ Presenters ~
Kwan Tak Wai
Chu Kean Chern
What is Virus
• A computer virus is a program
that can copy itself and infect the
computer without the permission
of the owner .
How viruses spread
Viruses can be spread by :
~ Downloading a file which contains
virus from the internet.
~ Receiving an email attachment that
~ Opening a given website link from
someone which is a virus website.
How virus avoids being detected
Viruses can prevents being detected in many ways ,
the following is the main prevention method :
~ Encryption . Viruses use encryption to hide their
identity . For example , you type the words “ABC” ,
then you encrypt the words you just typed , and
then the words “ABC” will become fake words like
“DEF”. (Also known as encrypted words)
Examples of Virus
• Trojan Horse
• Salami Attack
These are 2 examples :
What is Trojan Horse
• A trojan horse is a program that will do
harm to the computer quietly.
You download a free online game and install it.
When you are installing the game , the trojan
also will be installed without your awareness.
You play the game everyday , in the same time ,
the trojan will silently record the keys you have
pressed while typing your password and send it
to the creator of the trojan.
What is Salami Attack
• Salami attack is a program that steals commission
from someone without being noticed.
A bank worker insert a pen drive into a computer
that controls all the account of every customer ,
then the pen drive starts to transfer a small
amount of money from every customer’s account
to the bank worker’s own account without the
• Have at least one antivirus on your
• Always keep your antivirus
• Scan your computer through
antivirus at least once a week.