Virus and its types in detail

1. VIRUS
AND
ITS TYPES

2. What is virus
What is a computer virus?
• A computer virus is a type of malware that, when executed, replicates by
inserting copies of itself (possibly modified) into other computer programs,
data files , or the boot sector of the hard drive; when this replication
succeeds, the affected areas are then said to be "infected". Viruses often
perform some type of harmful activity on infected hosts, such as
stealing hard disk space or CPU time, accessing private information,
corrupting data. However, not all viruses carry a destructive payload or
attempt to hide themselves.
• The vast majority of viruses (over 99%) target systems running Microsoft
Windows, employing a variety of mechanisms to infect new hosts, and
often using complex anti-detection/stealth strategies to evade antivirus
software.

3. How a computer virus spreads?
For a computer virus to spread through a computer system, or
network, it must be activated. This means that the file that contains the
virus must be opened, or executed in order for the virus to come to life.
After it gets activated, these viruses look for certain programs to infect.
The main and the important that you must note is that, all viruses seem
to do well is duplicate themselves within the programs they find, and
this is the main reason as to how they spread well.
1. Email attachments.
2. Rogue Websites.
3. Hackers/fake Anti Virus Software

4. TYPES OF VIRUS
Types of computer viruses
• Trojan Horse
A program written to deliver a malicious program that may then
cause destruction to your computer. A Trojan horse is delivered by
someone or hidden within another program that may seem harmless.
• Spyware
A program written to monitor your actions on a computer. A
common type of spyware is a key-logger program. This program can
record every key stroke and mouse click you make. Spyware can be
delivered via a Trojan horse program.

5. • Boot Sector Virus
Not so common anymore, but they were nasty little programs that got loaded into
your master boot record. Most commonly spread by floppy disks. These viruses
could then launch themselves before your operating system even loaded.
• Time Bomb
A virus written to execute at a later date or upon an action
performed. These programs lay dormant until an event occurs.
• Browser Hijacker
A virus that will over take your web browser and automatically redirect you to
another website.
• File Infector Virus
A virus that lives within a file, typically a .exe file. When the file is executed, it
will then run its nasty code.

6. • Adware
Adware is a form of malware. One word - pop-ups. Adware is
designed to pop up advertisements. Adware can be very annoying.
• Worms
Just a nasty little program to cause slowness in a network. A worm
will replicate itself and spread from computer to computer. Worms are
commonly spread through email attachments.
• Polymorphic Virus
A virus written to change itself in order to evade virus detection.

7. Ransomware
• Ransomware is a type of malicious software from cryptovirology that
threatens to publish the victim's data or perpetually block access to it
unless a ransom is paid. While some simple ransomware may lock the
system in a way which is not difficult for a knowledgeable person to
reverse, more advanced malware uses a technique called cryptoviral
extortion, in which it encrypts the victim's files, making them inaccessible,
and demands a ransom payment to decrypt them.In a properly
implemented cryptoviral extortion attack, recovering the files without the
decryption key is an intractable problem – and difficult to trace digital
currencies such as Ukash and Bitcoin are used for the ransoms, making
tracing and prosecuting the perpetrators difficult.

8. Ransomware attacks are typically carried out using a Trojan that is
disguised as a legitimate file that the user is tricked into downloading
or opening when it arrives as an email attachment. However, one high-
profile example, the "WannaCry worm", traveled automatically
between computers without user interaction.

9. THANK YOU