COMPUTER VIRUS

Created by Mark Anthony P. Maranga

OBJECTIVE To learn deeper of what computer virus

is To be immune of any computer virus

attack To be able defend against computer

virus

OUTLINE What is computer virus? Why do people create computer virus? Brief History of computer virus? How will you know you have a computer

virus? Different types of computer viruses Ways to prevent computer virus List of trusted free antivirus

WHAT IS COMPUTER VIRUSA computer virus is a program designed to harm or cause harm on an infected computer.

WHY DO PEOPLE CREATE COMPUTER VIRUS? To gain control

of or hack a computer and use it for specific tasks.

To generate money by using such malware as a cash machine.

To steal sensitive information (credit card number, password, personal details, date, etc.)

To prove that they are capable of writing virus.

Revenge against company, cripple a computer or network.

BRIEF HISTORY OF COMPUTER VIRUS John von

Neumann came up with

the theory about self-replicating programs in 1949.

1983 Fred Cohen comes up with

the term “computer virus”

Core Wars An application

not release until 1984.

It replicates itself every single time it was run in computer

Reaper Antivirus

application specifically designed to destroy core wars of an infected computers.

1980’S MS-DOS Most popular OS

when viruses becoming thick and fast.

The most targeted OS by “the brain” virus which release in Pakistan in 1986.

1988 Morris Worm for MSDOS

Created by Robert Morris, 23, a small virus that infected almost 6,000 computers

1999 Melissa Virus It managed to

infect thousands of computers at an alarming speed, causing over $80 million in damages

2000 I Love You Virus It managed to

infect millions of computers in just under a day

The virus sent usernames and passwords it found on the infected computer back to the author

2001 Code Red virus It infected over

700,000 of computers, causing damages in excess of $2 billion

2004 no more notable

viruses appeared due to sophisticated antivirus and firewall systems

HOW WILL YOU KNOW YOU HAVE A COMPUTER VIRUS? Your computer

runs unusually slow or freezes

People are receiving emails from you which you did not send

You get pop-up messages or advertisements

Slower than usual network or Internet speed

Files mysteriously appear or disappear from your computer

Your homepage changes and you can not change it back

Your hard drive free space keeps shrinking

DIFFERENT TYPES OF COMPUTER VIRUSES Macro Viruses These viruses infect the files created using

some applications or programs that contain macros such as doc, pps, xls and mdb.

They automatically infect the files with macros and also templates and documents that are contained in the file. They hide in documents shared through e-mail and networks.

Macro viruses include: Relax bablas Melissa.A 097M/Y2K

Memory Resident Viruses They usually fix themselves inside the

computer memory. They get activated every time the OS runs and end up infecting other opened files. They hide in RAM.

Memory Resident Viruses Include: CMJ meve randex mrklunky

Overwrite Viruses These types of viruses delete any

information in a file they infect, leaving them partially or completely useless once they are infected. Once in the computer, they replaces all the file content but the file size doesn’t change.

Overwrite Viruses Include: Trj.Reboot way trivial.88.D

Direct Action Viruses These viruses mainly replicate or take

action once they are executed. When a certain condition is met, the

viruses will act by infecting the files in the directory or the folder specified in the AUTOEXEC.BAT.

The viruses are generally found in the hard disk’s root directory, but they keep on changing location.

Direct Action Viruses Include: Vienna virus

Directory Virus Also known as cluster virus or file

system virus. They infect the computer’s directory by

changing the path indicating file location.

They are usually located in the disk but affect the entire directory.

Directory Viruses Include: dir-2 virus

Web Scripting Virus Most web pages include some complex

codes in order to create an interactive and interesting content.

Such a code is often exploited to cause certain undesirable actions.

They mostly originate from the infected web pages or browsers.

Web Scripting Viruses Include: JS.Fortnight – a virus that spreads

via malicious emails.

Multipartite Virus These type of viruses spread in many

different ways. Their actions vary depending on the OS

installed and presence of certain files. They tend to hide in the computer’s

memory but do not infect the hard disk.

FAT Viruses These lardy viruses attack the file

allocation table (FAT) which is the disc part used to store every information about the available space, location of files, unusable space etc.

FAT Viruses Include: the link virus

Companion Viruses These types of viruses infect files just

like the direct action and the resident types. Once inside the computer, they ‘accompany’ other existing files.

Companion Viruses Include: Asimov.1539 stator and terrax.1069

Polymorphic Virus They encode or encrypt themselves in a different

way every time they infect your computer. They use different encryption and algorithms. This makes it difficult for the antivirus software to

locate those using signature or string searches (since they are very different in each encryption).

Polymorphic Viruses Include: Marburg tuareg Satan bug elkern

Worm This program is very similar to a virus

and has the ability to self-replicate leading to negative effects on your computer.

Worm Viruses Include: lovgate.F sobig.D trile. C PSWBugbear.B Mapson

Trojans Trojans can illegally trace important

login details of users online. For example E-Banking is very common

among users, therefore, vulnerability of tracing your login details whenever your PC is working without any strong powerful antivirus installed.

Email Virus This is a virus spread via an email. Such a virus will hide in an email and

when the recipient opens the mail.

Browser Hijacker This virus can spread in many different

ways including a voluntary download. If infects certain browser functions

especially in form of re-directing the user automatically to certain sites. A good example is

Browser Hijackers Include: the cool web search

Boot Infectors They include the boot sector plus

master boot record types. All the viral codes can be separate

location; however they infect the hard disks or the floppy.

Boot Infectors Include: the brain virus -it is the very first wild

virus to be created. From what we have seen, the many

types of computer viruses and their effects are very harmful and can completely damage your system. Always make sure your system is up to date. Also install antivirus software. The antivirus program protects your computer and the personal information in it.

 

WAYS TO PREVENT COMPUTER VIRUS Don't open unknown attachments in

emails or do a virus scan after opening them. 

(If you get an email from a person that contains one or more viruses, the viruses may infect files in the computer.

The viruses might also send emails to people from your email address book or email folders automatically).

Download files only from trusted sites.

 If you download a program or a data filefrom the Internet or other shared networks, viruses might be transferred to your computer.

Sometimes the free software programs on the Internet have viruses especially if you are downloading from sources such as Torrent or Usenet newsgroups.

Remember to do a virus scan for them after peripheral devices are connected to your computer. 

The devices such as MP3 players, USB thumb drives, memory cards or CD drives are also means of spreading viruses.

LIST OF TRUSTED FREE ANTIVIRUS AVG Avira Avast Microsoft Security Essentials Malwarebytes Panda Cloud AntiVirus Comodo Firewall + Antivirus