Viruses can enter computers in several ways. There are many types of viruses including resident viruses, overwriting viruses, macro viruses, polymorphic viruses, and Trojan horses. It is important to take steps to protect computers such as installing antivirus software, using firewalls, avoiding suspicious emails and downloads, and regularly backing up files.

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2. Virus stands for Vital
Information Resource
under Siege.
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3. How do viruses come to the computer?
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How do viruses come to the computer?
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4. SYMTOMPS OF VIRUS INFECTIONSYMTOMPS OF VIRUS INFECTION

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6. VIRUSES
 A resident virus is a kind of
computer virus that hides
and stores itself within the
computer memory, which
then allows it to infect any
file that is run by the
computer, depending on the
virus’ programming.
 The virus goes into action
when a specific condition is
met.
 infects the files in the folder
where the virus is located as
well as the directories
specified in the Autoexec.batvirus’ programming.
 examples: Randex , CMJ
,Meve, and Mrlunky
specified in the Autoexec.bat
file path.
 example : Vienna virus
The virus goes into action
when a specific condition is
infects the files in the folder
where the virus is located as
well as the directories
specified in the Autoexec.bat
 An overwriting virus is a
malicious program which,
after infection, will effectively
destroy the original program
code, typically by overwriting
data in the system's memory.
 examples: Way, Trj.Rebootspecified in the Autoexec.bat
example : Vienna virus
 examples: Way, Trj.Reboot
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7. VIRUSES
 It infects the computer
storage sector where startup
files are found.
 The boot sector contains all
the files required to start the
operating system (OS) and
other bootable programs.
 A macro virus is a computer
virus that "infects" a Microsoft
Word or similar application
and causes a sequence of
actions to be performed
automatically when the
application is started or
something else triggers it.other bootable programs.
 The viruses run at bootup,
allowing them to execute
malicious code during
startup time -- before many
security layers are executed,
including antivirus software.
eg: Polyboot.B
something else triggers it.
 Macro viruses tend to be
surprising but relatively
harmless.
 example: Relax, Melissa. A
Metys
A macro virus is a computer
virus that "infects" a Microsoft
Word or similar application
and causes a sequence of
actions to be performed
automatically when the
application is started or
something else triggers it.
 These viruses change the
path that indicates the
location of a file.
 When you execute a .COM or
.EXE file infected by virus,
you accidently run the virus
program.something else triggers it.
Macro viruses tend to be
surprising but relatively
example: Relax, Melissa. A,
program.
 It is impossible to locate the
original files after it is
infected.
 example: Dir-2 virus
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8. A polymorphic virus is a It is a type of malware that
VIRUSES
 A polymorphic virus is a
complicated computer virus
that affects data types and
functions. It is a self-
encrypted virus designed to
avoid detection by a scanner
 Upon infection, the
polymorphic virus duplicates
 It is a type of malware that
infects executable files with
the intent to cause permanent
damage or make them
unusable
 A file-infecting virus
overwrites code or inserts
infected code into apolymorphic virus duplicates
itself by creating usable,
albeit slightly modified,
copies of itself.
 example : Taureg
infected code into a
executable file.
 example: Cleevix and Cascade
It is a type of malware that A companion virus is aIt is a type of malware that
infects executable files with
the intent to cause permanent
damage or make them
infecting virus
overwrites code or inserts
infected code into a
 A companion virus is a
complicated computer virus
which, unlike traditional
viruses, does not modify any
files. Instead, it creates a copy
of the file and places a
different extension on it,
usually .com.
infected code into a
executable file.
example: Cleevix and Cascade
 This unique quality makes a
companion virus difficult to
detect
 example: Terrax.1069
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9. VIRUSES
 A FAT virus is a computer virus which attacks
the file allocation table (FAT), a system used in
Microsoft products and some other types of
computer systems to access the information
stored on a computer.
 It is considered as a very dangerous virus .
Damage caused can result in information losses Damage caused can result in information losses
from individual files or even entire directories.
Damage caused can result in information losses
 They are not considered viruses because they
do not replicate.
 A logic bomb is a piece of code inserted into
an operating system or software application
that implements a malicious function after a
certain amount of time, or specific conditions
are met.
Damage caused can result in information losses
are met.
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11. VIRUSES
 A Trojan horse program is a file that appears
harmless unless it is executed.
 A destructive program that pretends to be a
useful application, but harms your computer or
steals your information after it's installed.
 The name Trojan Horse has been derived from
the Greek mythology.
 The name Trojan Horse has been derived from
the Greek mythology.
useful application, but harms your computer or
The name Trojan Horse has been derived from
 A computer worm is a self-replicating
computer program that penetrates an
operating system with the intent of
spreading malicious code.
 Worms utilize networks to send copies of
the original code to other computers,
causing harm by consuming bandwidth or
possibly deleting files or sending documents
The name Trojan Horse has been derived from causing harm by consuming bandwidth or
possibly deleting files or sending documents
via email.
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 Most Antivirus companies have come up with their
internet security suites over antivirus which is the
need right now. You must have one from reputed
providers in the industry such as Kaspersky, Eset,providers in the industry such as Kaspersky, Eset,
Symantec etc. Remember “cheap” always isn't good.
The product which claims to give you 100%
protection is misleading you.
 Whether you use Windows/Mac or any Linux based
distribution you must have it updated with latest
security patches.
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 Have a firewall installed and updated.
 Stop opening emails from unknown sources serving
you with attachments intended to not only Spam but
to make things like ransomware attacks happen.

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 Scan your computer for viruses, malware
everyday/weekly by scheduling it into your security
product.
 Do not plug and play USB drives without scanning it
properly.properly.
 Stop downloading and going for the free tag over the
internet when it comes to softwares. Most of them
come with bundled adwares, popups, malwares, weird
browser extensions that will slow down your computer.
 Look for “https://” tag when browsing a website. These
websites are encrypted and usually safe. But don't be
mistaken. Sites which spread piracy and illicit content
use them too these days by faking https certificates.
Install Ublock Origin, Ghostery, Https Everywhere, Install Ublock Origin, Ghostery, Https Everywhere,
Privacy Badger extensions for Chrome/Firefox to block
most of the popups and malicious ads.
 Always check the file extension of a file you're about to
open after downloading from the internet. A .mp3 file
having a .exe extension means you're on the wrong
boat.

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Defense : Level advanced
 Encrypt your entire computer right away at least (AES256 with SHA512) . Windows
users : BitLocker, Veracrypt etc. Linux users can encrypt their entire partition at
time of installation itself!time of installation itself!
 Install “KeyScrambler” if on Windows which encrypts every keystroke from your
keyboard protecting you from keyloggers.
 Use a Password Manager like Lastpass/Dashlane. Get a reputed VPN like PIA,
NordVPN, ExpressVPN, F-Secure Freedom etc. Free ones transport your data to
places you couldn't imagine.
 Use Two Factor Authentication everywhere you can.
 Have regular backups on external HDD and encrypt them too. Just remember the Have regular backups on external HDD and encrypt them too. Just remember the
password.
 Check your hosts file in Windows for any unidentified website and delete them.
Hosts file is locates in : C:/Windows/System32/drivers/etc/hosts. Open it with
notepad and do the intended.
 Never store financial information or documents of self without having proper
protection or be a victim of identity theft. Save them in encrypted folders if
needed.
Encrypt your entire computer right away at least (AES256 with SHA512) . Windows
users : BitLocker, Veracrypt etc. Linux users can encrypt their entire partition at
Install “KeyScrambler” if on Windows which encrypts every keystroke from your
Use a Password Manager like Lastpass/Dashlane. Get a reputed VPN like PIA,
Secure Freedom etc. Free ones transport your data to
Use Two Factor Authentication everywhere you can.
Have regular backups on external HDD and encrypt them too. Just remember the
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Have regular backups on external HDD and encrypt them too. Just remember the
Check your hosts file in Windows for any unidentified website and delete them.
Hosts file is locates in : C:/Windows/System32/drivers/etc/hosts. Open it with
Never store financial information or documents of self without having proper
protection or be a victim of identity theft. Save them in encrypted folders if

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22. “www.quora.com
Reference
 www.quora.com
 Internet, Web designing and
cyber security textbook.
 www.technopedia.com
 www.google.co.in/imghp
“www.quora.com
Reference
www.quora.com
Internet, Web designing and
cyber security textbook.
www.technopedia.com
www.google.co.in/imghp