© Vera Castleman

Threats

Grade 10

Threats

A computer virus is a computer program that invades your computer system without your knowledge and consent

It hides itself while doing its work. Frequently e-mails attachments spread

viruses

Basic Characteristics

It is able to duplicate itself: It could replicate or attach itself to a file which when shared will

infect the next computer. It is able to hide and protect itself It must have a PAYLOAD.

Types of threats

Trojan Horse Boot Sector Virus File Virus Worms Time Bombs Macro Viruses

Benign or malignant?

Benign When activated does something harmless but irritating When it has stopped running you are given control of your

computer again. Generally written as jokes

Malignant Written to cause damage to files It can replicate rapidly and infect data and program files

within minutes of entering your system.

Who Writes a Virus?

Malicious people who have some sort of grudge.

Bored students who need something to stimulate their creative powers.

Pranksters who think it is amusing.

Damage Caused by a Virus

It can cause damage any file on your hard drive or memory stick e.g. drivers.

Businesses Clearing up is time-consuming and costly. It requires the services of a specialist in the field. Essential data could be lost

Home Loss of data Inconvenience because you may have to reformat your

hard drive.

Infection rate A virus can transfer copies of itself dozens of times

in a matter of seconds. In the workplace, computers are usually networked.

If a computer is infected every machine in the company could be infected almost instantly.

If each worker takes an infected USB home, each home machine becomes infected.

If each spouse takes an infected USB to work and if each child takes an infected USB to school you will have a pandemic.

Does your computer have a virus?

Strange messages or graphics appear on your monitor. Sounds that are not part of your program could be played. Your hard disk could reformat itself without you having given the

reformat command. Unknown files or directories are created. Files expand in size for no known reason. Files are corrupted. Your computer starts to work slowly. The computer is unable to boot up because the boot sector has

been relocated. The FAT has been moved and it appears that you have no files

on your disk.

Cleaning an infection

Reformatting the hard drive is extreme but undesirable

Use an inoculation programs. These programs find the virus and

destroy or quarantine it. They may try to patch the damage They can fix a known virus they

cannot fix a virus that is still to be written.

What are virus definitions?

These define what a virus is and what it can do. When a company finds a new virus they get into the program code and look for the defining part of the virus. They write code to defuse or destroy the virus.

Update your virus definitions

The fact that the old viruses can be treated is a stimulus to their authors. You can almost hear them saying “They found that one! Let’s see how long it takes them to crack this new one!” and out will pop a new virus. This is then analysed by the anti virus companies until they find the program that will crack that new virus and so the vicious circle starts again!

How to Prevent Infection Only use new software bought from a reputable agent. Isolate your machine if you can!

Ensure that a computer is clean before you use your USB Install a virus checker in your home computer and convince your

company and friends to do the same. Update your virus checker’s data base regularly. Download files from reputable sites on the Internet. Don’t boot with a USB in place. Change your CMOS setting so that drive C is the first drive it

examines on boot-up. Scan all disks with your virus checking software before using

them. Don’t open attachments from a strange source.

Hoax

You will often receive an e-mail warning you not to open an e-mail with a particular subject line because it is a virus. Most of these are a hoax. Hoaxes cause panic and flood inboxes throughout the world. Before sending these warnings check on the Internet.

Spam

This is unsolicited e-mail. In businesses it clutters up the inbox and uses space on the server. You can build in a filter that will delete all e-mail from a particular person as soon as it is received.

Phishing When someone wants to gain access to your private details like

passwords or bank details, they will use bait in the form of an e-mail or text message hoping to catch the “phish” – you! They could be attractive offers (“You have won £500,000 in the

UK Lottery. Send us your details so that we can transfer the money to your account”) or

Could cause you alarm (“We have noticed some unusual activity on credit card. Click here so that we can verify your details.”).

Keyloggers are programs that capture all keystrokes as you type in the hopes that soon a password will be entered. The “Phisher” has access to your computer through this program

and will patiently wait until he can pick up personal details.

E-mail spoofing

Most of us will open a friend’s e-mail. E-mail spoofing relies on this.

E-mail spoofing is often used to gain access to certain details that could be used in Spam or in Phishing.

Pharming

Pharming is an attempt by a hacker to block a legitimate web site. The people who type in the web address of this site will be redirected to a false web site. One of the main purposes of pharming is to assist in identity theft particularly if an on-line banking site is affected.

Some other threatsTwishing Phishing using Twitter

Smishing Phishing using an SMS

Vishing Phishing using VOIP