Computer Virus
[ 1 ] What is a
Computer Virus ?
- A computer virus is a type of malicious software (malware) that
is designed to infect a computer system, replicate itself, and
spread to
other computers.
- These viruses are named after biological viruses because they
share some similarities in behavior.
- A computer virus is a program which can harm our device and
files and infect them for no further use.
- When a virus program is executed, it replicates itself by
modifying other computer programs and instead enters its own
coding.
- This code infects a file or program and if it spreads massively, it
may ultimately result in crashing of the device.
[ 2 ] History of Computer Virus
- Viruses have been infecting various devices for a long term via
the Internet or some other medium.
- The viruses are created with an intention to steal information,
completely destroy the device
- The first computer virus was known as “Elk Cloner” and was
built in 1982, by Rich Skrenta.
- It spread by a floppy disc with a game on it and hooked itself to
the Apple II operating system.
[ 3 ] What Does a
Computer Virus Do ?
- A virus can harm or destroy data, slow down system resources,
and log keystrokes, among other things.
- A virus has the ability to have unexpected or harmful outcomes
during this procedure, such as destroying system software by
corrupting data.
- ome computer viruses are designed to damage your computer
by destroying files, corrupting applications, or reformatting the
hard drive.
- Other viruses may just clone themselves or flood a network
with traffic, rendering all internet activity difficult.
[ 4 ] How a Computer gets A Virus ?
- Sharing the data like music, files, and images with each
other.
- If you open a spam email or an attachment in an email that is
sent by an unknown person.
- Downloading the free games, toolbars, media players, etc.
- Visiting a malicious website.
- Installing pirated software(s) etc.
Common Signs of
Computer Viruses
- Opening of Pop-up window frequently.
- Slowing down of system without any reason.
- Identifying that your files are corrupted.
- Change in the name of your hard drive & also change in its
volume.
- Change in amount of free memory available.
- Not able to find your files or programs.
- Unknown change in the password that does not let you
login.
- A virus may damage your hard drive and our device may freeze
or crash as a result of this.
[ 5 ]
- Viruses are classified on the basis of their mode of
existence and there
are three categories of viruses
1. BOOT Infectors
2. SYSTEM Infectors
3. GENERAL EXECUTABLE PROGRAM Infectors.
1 . Boot Infectors
- A boot sector virus is a type of virus that infects the boot sector
of floppy disks or the primary boot record of hard disks
- While boot sector viruses infect at a BIOS level, they use DOS
commands to spread to other floppy disks.
- Some boot sector viruses attempt to hide their presence and
may be difficult to detect.
- Modern operating systems and computer security measures
have made it more difficult for boot sector viruses to infect
systems, but they
can still be a concern in some situations.
2. System Infectors
- This second category of viruses deals with the components of
the system itself
- System infector viruses were more common in the early days of
computer viruses and played a significant role in the evolution
of malware.
- System infectors, also known as file infectors or executable
infectors, are a type of computer virus that primarily targets
executable files on a computer system.
- Like other viruses, system infectors are capable of self-
replication. When an infected executable file is executed, the
virus code is activated and may infect other executable files on
the system.
- The virus is typically activated when an infected executable is
run.
- Some famous examples include the CIH/Chernobyl virus and
the Sasser worm.
3. General Executable Program Infectors.
- From the infection point of view, these viruses are most
dangerous and devastating of the three classes of viruses.
- They attach themselves to program files and can spread to
almost any executable program in any system.
- These viruses change the original program instructions into a
"jump" to its own code and follows that code with a return to
the original program
- By attaching themselves to .EXE or COM files
- some famous examples Melissa Virus, Blaster Worm
[ 6 ] Examples of Computer Viruses
- Morris Worm : One of the first and most widespread computer
viruses, this self-replicating computer program spread across
the early Internet
in 1988, delaying or crashing many devices.
- Nimda : In 2001, this type of worm targeted web servers and
machines running Microsoft Windows, propagating via several
attack vectors.
- ILOVEYOU : A extremely damaging worm that spread via email
disguised as a love confession and overwrote data, causing
extensive damage in
2000.
- SQL Slammer : A computer worm that propagated quickly in
2003 by exploiting a vulnerability in Microsoft SQL Server,
causing network
congestion and disabling Internet services.
- Stuxnet : It was a sophisticated worm that was built in 2010 to
target and damage industrial control systems, primarily Iran’s
nuclear program, by exploiting zero-day vulnerabilities.
- CryptoLocker: In 2013, this ransomware Trojan infected
hundreds of thousands of computers, encrypted victims’ files
and demanded a fee
to unlock them.
- Conficker : This worm, which first appeared in 2008, targeted
vulnerabilities in Windows operating systems, resulting in the
creation of a vast botnet and widespread infestation.
- Tinba : This banking Trojan, discovered in 2012, primarily
targeted financial institutions, attempting to steal login
passwords and
banking information.
- Shlayer : Since 2018, a macOS-specific Trojan has been
distributing adware and potentially unwanted programs via
bogus software
updates and downloads.
[ 7 ]
- Use Antivirus Software
- Keep Software Updated
- Enable a Firewall
- restrict the use of outside floppies
- the use of pirated software should be stopped.
- restrict the use of outside floppies
- Use a pop-up blocker with your internet browser
- Don’t open email attachments or click on hyperlinks from
unknown senders
- Don't open messages from unknown senders
[ 8 ] What is
Antivirus?
- An anti-virus is a software which comprises programs or set of
programs which can detect and remove all the harmful and
malicious
software from your device.
- Antivirus can also detect and remove other dangerous software
such as worms, adware, and other dangers.
- Antivirus is available for free as well.
- Anti-virus software that is available for free only provides
limited virus protection, whereas premium anti-virus software
offers
more effective security.
- Antivirus example
Norton Antivirus
F-Secure Antivirus
Kaspersky Antivirus
AVAST Antivirus
Comodo Antivirus
McAfee Antivirus
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