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Viruses worms trojan horses lisa
1.
2. programs which can destroy
or cause damage to data
stored on a computer
system and to the computer
itself!
Virus program must be
executed in order to dirty a
computer system. Viruses
can attach themselves to
other programs in order to
ensure that this happens.
3. A computer virus is a computer program that can
copy itself and dirty a computer without
permission or knowledge of the user.
4. Do not damage the original program or damage
the hardware
◦ May damage data files
◦ “trash” firmware
But, some do
For this reason most can be cleaned up with anti-
virus software.
5. User call for a legal program
The virus code, having inserted itself in the order
of execution, executes in its place or in addition to
the legal program.
The virus code terminates and returns control to
the valid program
6. Turn off file sharing on the desktop or if you
need some kind of file sharing, apply user-level
security.
Don't open email attachments from unknown
senders, especially files with an "exe", "vbs",
"com" or "pif“.
All downloaded files from email should be
saved to disk first and then virus scanned to
determine if they are virus free before
executing them.
7. Displaying unwanted
messages
Loss of Data from a
storage medium
Computers restarting
unexpectedly
Unwanted generation of
emails
8. Corrupt or delete data
Disable the computer by
changing the operating
system
Cause silly messages to
be displayed or sounds to
be produced
9. Worms operate
differently to viruses
Worms can spread
themselves to other
computers without
needing to be transferred
as part of a host
program.
The first time a user may
notice the presence of a
worm is when the
computers memory
UNEXPECTEDLY fills up
10. A worm is self-replicating software designed to spread
through the network
◦ Can cause huge damage
Access sensitive information
Cause confusion by corrupting the sensitive information
Worm vs Virus
A virus is code embedded in a file or program
Worms are self-contained and may spread autonomously
11. A Virus is a hateful program that spreads using a
transmission technique that generally requires user
involvement, and always have a hateful target
A worm on the other hand, has ability to self-spread,
and may or may not have nasty purpose.
12. Capable of severely slow down the working of the
internet
To unable us to build better defense systems
To unable possible good application
The worst is yet to come!
13. Morris worm, 1988
◦ Infected about 6,000 machines
10% of computers connected to the Internet
Code Red worm, July 16 2001
◦ Infected more than 500,000 servers
◦ Caused ~ $2.6 Billion in damages,
14. Mimili and Mimail.F are email
worms cover themselves as
an email from the PayPal on-
line payment service and try to
steal credit cards info.
This method of fraud is known
phishing