Viruses and worms are malicious programs that can damage computers. Viruses attach themselves to files and spread when those files are opened, while worms can spread automatically from one computer to another without human action. Basic virus structure involves looking for infectable objects, infecting them, and then returning control to the infected program. Worms differ in that they replicate and spread automatically between systems rather than needing a host program. Protecting against viruses and worms involves keeping systems updated, using antivirus software, conducting regular scans, and employing a firewall.

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2. VIRUSES AND WORMS
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3. VIRUS
Viruses are malicious programs that can cause
damage to computer.
A computer virus attaches itself to a program or
file enabling it to spread from one computer to
another leaving infections as it travels. Almost
all viruses are attached to an executable file
which means the virus may exist on computer
but it actually infect our systems unless we run
or open the malicious program.
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4. A virus cannot be spread without a
human action (such as running an
infected file or program) to keep it
going.
A virus is spread by sharing files or
sending emails with viruses as
attachments in the email.
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5. How they work:
Basic structure:
{
look for one or more infectable objects
if (none found)
exit
else
infect object
}
Doesn’t remain in memory, but executes all of
the viral code at once then returns control to the
infected program
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6. Ways to infect computer systems through
viruses.
Boot Sector Penetration
Macros Penetration
Parasites
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7. WORMS
A worm is similar to view by design and is
considered to be a sub-class of a virus.
Worms spread from one computer to another it has
the capability to travel without any human action.
It is an independent program that does not modify
other programs, but reproduces itself over and over
again until it slows down or shuts down a computer
system or network.
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8. It uses computer network to spread itself.
It consumes too much system memory
Infects the environment rather than specific
objects
Worms send a copy of itself to everyone
listed on your email address book.
.
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9. Difference between viruses and worms.
A virus an worms are similar in that they are both
forms of malicious software. The virus code is
injected into the previously benign program and is
spread when the program is run.
Examples of virus carrier programs are games, e-
mail attachments and animations
A worm is a malicious software which replicates
itself. A worm spreads from system to system
automatically, but virus needs another program in
order to spread.
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10. Characteristics of a Worm
Enhanced Targeting
Enhanced Speed
Enhanced Capabilities
Enhanced Destructive Power
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11. Phases of a worm or virus operation
Dormant Phase
Propagation Phase
Triggering Phase
Execution Phase
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12. Types of viruses
Stealth Virus
Polymorphic Virus
Parasitic Virus
Memory-resident Virus
Boot Sector Virus
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13. Protecting your Computer System
To ensure that your OS is up-to-date
To have antivirus software and make sure it has
the capability to scan e-mail and files as they are
download from the internet
Need to run full disk scans periodically
Use a Firewall.
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