COMPUTER VIRUS (1 - 2) - DEFINITION, TYPES, EXAMPLES, VIRUS WARNING SIGNS, VIRUS DETECTION, AND EXAMPLES OF ANTIVIRUS SOFTWARE (JS3 NOTES)

COMPUTER VIRUS (1 - 2) 

DEFINITION, TYPES, EXAMPLES, VIRUS WARNING SIGNS, VIRUS DETECTION, AND EXAMPLES OF ANTIVIRUS SOFTWARE 

Definition of Computer Virus

1. A computer virus is a small software program that interferes with computer operation and spreads from one computer to another.
2. A virus is a self-replicating program that copies itself and that can infect other programs by modifying them or their environment such that a call to an infected program implies a call to a virus. It is a program written by software developers to check piracy on some of their system and application software.

Types of Computer Viruses

1. Boot Sector Virus:
This type of virus infects the master boot record. It is challenging and a complex task to remove this virus and often requires the system to be formatted. Mostly it spreads through removable media.
2. Direct Action Virus:
This is also called a non-resident virus, when executed scans the disks for targets, infects them, and then exits (i.e. it does not remain in the memory after it is done executing).
3. Resident Virus:
Resident virus installs itself as part of the operating system when executed, after which it remains in the RAM from the time the computer is booted up to when it is shut down.
4. Multipartite Virus:
This type of virus spreads in multiple ways. It infects both the boot sector and executable files at the same time.
5. Polymorphic Virus:
These types of viruses are difficult to identify with a traditional anti-virus program. This is because polymorphic viruses alter their signature pattern whenever it replicates.
6. Overwrite Virus:
This type of virus deletes all the files that it infects. The only possible mechanism to remove is to delete the infected files and the end-user has to lose all the contents in it. Identifying the overwrite virus is difficult as it spreads through emails.
7. Space filler Virus:
This is also called “Cavity Viruses”. This is called so as they fill up the empty spaces between the codes and hence do not cause any damage to the file.
8. Macro viruses:
As the name suggests, macro viruses particularly target macro language commands in applications like Microsoft Word. The same is implied on other programs too.

Examples of Viruses

Some of the known viruses are:
a. Trojan horse virus
b. Sleeper
c. Logic bomb Alabama virus
d. Christmas virus
e. Jerusalem virus
f. Resident virus
g. Nonresident virus
h. Code Red
i. I love you
j. Creeper virus
k. Stone
l. November 17

Sources of Virus

These are the means through which viruses could be spread from one system to the other.
i. Infected memory devices
ii. E-mails attachments
iii. Internet downloads
iv. Computer network
v. Illegal duplication of software/cracked software
vi. Unsecured websites

Virus warning signs

Some of the virus warning signs are listed below
i. Slowing down response time
ii. Presence of tiny dots
iii. Wandering cursor across the screen
iv. Incomplete saving of files
v. Corruption of the system set-up instruction
vi. The appearance of strange characters
vii. Insufficient memory space in a hard disk when you have enough memory space
viii. Frequent system crash
ix. Unfamiliar applications or processes appearing on the background

Virus Detection (Anti-Virus)

Anti-viruses are also written programs by software developers to stop and curb the spread of the virus in a system. Antivirus software is a type of utility software used for scanning and removing viruses from your computer. Once an anti-virus is installed on a system, it will be hard for a virus to enter the system except if the antivirus is outdated. All antivirus can be updated on the internet.

Examples of Antivirus Programs

Computer Antivirus programs include:
i. Norton Anti-virus
ii. McAfee
iii. AVG
iv. Bitdefender
v. Panda Dome
vi. Trend Micro
vii. Malwarebytes
viii. Avira Prime
ix. Intego
x. TotalAV
xi. Bitdefender Total Security
xii. Dr Solomon’s Tool Kit
xiii. Penicillin
xiv. Avast
xv. Windows Defender
xvi. Kaspersky

Computer Virus Preventive Measures

Computer virus preventive measures include:
1. Install a good Computer Antivirus.
2. Timely update of the operating system.
3. Timely update of antivirus software
4. Installation of only trusted or licensed software
5. Exercise care when browsing the internet

CLASS ACTIVITIES

1. Define Computer Virus

2. Define any two (2) types of virus

3. State two (2) sources of virus and virus warning signs

4. Define Antivirus and list three (3) examples of antivirus software.