Malware comes in many forms and can harm computers and steal information. Common types of malware include viruses, trojans, worms, rootkits, and spyware. Viruses replicate and spread while infecting files. Trojans seem innocuous but delete or corrupt files once installed. Worms spread automatically between devices without needing files. Rootkits hide other malware to gain access and attack. Spyware secretly monitors users' online activity without permission to collect personal information. Users should be aware of malware's threats and symptoms to protect their devices and privacy.

1. HARMFUL SOFTWARE
Malware and Virus

2. Software and Computer
 Software is an inseparable component of the computer
 Different types of software have made our work easy
BUT…
Some software that are very harmful for our system and data

3. Malware
 Combination of two words
Malicious + Software
Software written and developed to create mischief or hurt the user
Various types:
 Virus
 Trojan Horse
 Worms
 Rootkits
 Backdoors
 Ransomware
 Spyware
 Adware
 Sacreware

4. Purpose of Malware
 In the beginning Malware was written for purpose of
experiments.
 Sometimes, it was also written as a joke.
 With advancement in technology, it is being used with
more intensions:
 Steal Personal informations
 Obtain bank account details and credit card details.
 Disturb activities
 Take control of users computer for illegal activities
 Send email spams
 Advertise products

5. Symptoms of presence of Malware
 Unexplained messages start appearing on the screen
 Some files deleted on their own.
 Keyboard does not work properly
 Unexplained problems occur while printing files
 Making system unusable/ crashing of the system
 Slowing down of your system
 Automatic rebooting/restarting
 Data on the system becomes inaccessible
 Random playing of strange sounds

6. Types of Malware
1. Virus
 The term ‘VIRUS’ was first used by John Von Neumann in 1949
 A computer virus is nothing but an electronic version of ‘Biological virus’
Vital
Information
Resource
Under
Siege
 When enters the computer, it replicates itself and cause infection.
CREEPER is widely acclaimed as
the first virus on ARPANET
(First version of Internet)

7. Types of Viruses
 File Infector Virus: This virus attacks executable files of the computer.
 This virus either deletes or damages files.
 Eg: Sunday, Invader, Cascade
 Boot Sector Virus: Infects the boot sector of hard disk
 Either copies boot sector instructions present in hard disk to some other
location or overwrites these instructions
 Eg: Disk Killer, stone Virus
 Macro Virus: Infects the macro files of MS Office files
 Difficult to detect(They enter the system as a part of office file and appear
non-suspesious)
 Eg: Nuclear, DMV

8. 2. Trojan Horses
 These are ordinary looking files but are actually programs
that delete/ corrupt files.
 They are transferred as innocent attachments to an email.
 They do not replicate themselves.
 They are usually written with the intention of stealing
data.
 These are used to take unauthorized access and control of
infected system.
 Eg: PC-Write (First Trojan Horse in cyber history)

9. The Trojan Horse can:
 Crash the computer
 Corrupt user data
 Format HD
 Make unauthorized transfer of data/electronic money
 Modify/delete data
 Unnecessary download or upload files
 Control computer remotely

10. 3. Worms
 Viruses are transferred from one system to another as an
attachment to a file or a program.
 Worms can spread on their own. (Do not need the support
of another file)
 Worms are designed only to spread from one computer to
another.
 NOT TO CAUSE CHANGES IN DATA OF THE SYSTEMS.
 Some worms cause problem of increased network traffic.
 Eg: Red Code, Slammer worm, Storm

11. 4. Backdoors
 When you log into a computer system, it asks for the user
name and password
 Backdoor malware has been designed to bypass this
process
 It can get installed to a computer with/without the
knowledge of the user.
 Eg: Subseven, NetBus, Award BIOS

12. 5.Rootkit
 Rootkit is a special type of malware that gives
administrative rights to use the computer.
 Unlike other malware, they are not harmful.
 They are simply cover other malware, gain entry to the
computer and then attack the computer using other
malware like virus, Trojan etc.
 Eg: Back Orifice

13. 6.Spyware
 Spyware is a type of malware that does not
corrupt the computer
 It is designed to collect personal information
about an individual/ organization.
 It is designed to collect informations like web
visiting history of the user
 advertisement start appearing according to
the web visiting history
 Some spyware designed to download unwanted
softwares/files form internet.
 It does not multiply

14. Symptoms of spyware infected systems:
 Performance of the computer has started
decreasing.
 The free space in the computer HD has
decreased on its own.
 Huge network traffic
 Applications installed on the computer
started closing in their own.
 User has started facing difficulty in
connecting to the computer.

15. Check your knowledge:
 Macros present in ……………………….. File.
 Ans: Office file
 Malware is written and developed to
create…………… or ………………….. The user.
 Ans: Mischief or Hurt
 ………………… collects information about an
individual or an organization.
 Ans:Spyware
 ………………………. Is considered as the first Trojan
Horse in cyber history
 Ans:PC-write
 …………………….. Is widely acclaimed as the first
virus on ARPANET
 Creeper