E-mail Viruses


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Tutorial Overview

Topics covered in this tutorial (click link to jump to topic):

1. What are computer viruses? 7. To be really sure
2. What do they do?   Others
3. Are Mac's any more or less susceptible? 8. What is Spyware?
4. Where do they come from? 9. Pop ups
5. What are the Best Anti Virus Programs? 10. What is Adware?
6. How do they work? 11. What is Phishing?

What are computer viruses?

A computer virus is malicious code that is engineered to replace or destroy legitimate files or disable functions on your computer. Computer viruses are "executable". This means they can be double clicked and "run" like any other program on your pc. However unlike other programs on your computer they have undesirable consequences. Extended definition.

What do they do?

Generally today's viruses:

  • Replace or rename Windows system files
  • Attempt to destroy hard drive partitioning or attack the operating system in some way
  • Write themselves into your computer's registry and therefore reinstall themselves each time you restart your computer.
  • They sometimes set their own attributes to "hidden" so they are less easy to find
  • Replicate themselves and send themselves from your computer to other computers

There are a number of web sites that describe the precise behaviours of every known virus. My favourite is Symantec Security Centre (the maker of the Norton's products).

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Are Mac's any more or less susceptible?

Generally, the answer to this question has to be "yes". The long answer though is that the vast majority of personal computing is performed on various Windows operating systems, like 90%. For this reason, people who write viruses target Windows. Recently though, Mac has also begun to be targeted.

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Where do they come from?

People write them. It is a sad fact. Like people who light bush fires or vandalise your car or deface your fence… they want to spoil things for others. They enjoy taking advantage of people who are less informed about computing than themselves. Or they want to make the point that the most common operating system in the world is extremely prone to malicious attack. Or they are competing with their peers by trying to write a virus that is more damaging and wide spread or "wild" than others. All this is speculation though, see more here.

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What are the Best Anti Virus Programs?

This is a very good question. Although programs come and go in terms of effectiveness, here is a short list:

Here is an extended list of anti-virus programs.

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How do they work?

An Anti Virus program sits between you and a virus executing. For example, an Anti Virus program starts up when you start your computer and from then on it inspects every file you open or save to see if it contains a virus. Similarly, when you receive email, it checks all inbound and outbound email for attachments that contain viri. If it detects a virus, it "quarantines" it, that is, makes it non executable.

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To Be Really, Really Sure

Let's say you want a second opinion on whether your PC is clean of viri. Or you don't trust your AV product. Or you think your AV product may have missed something. There are a couple of web sites that use Active X controls from within your browser to install and run a virus checker on your PC. The best in my view is Panda Active Scan. Symantec have a tool too.

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Other Security Issues

What is Spyware?

Spyware is another type of software that installs in the background without your express knowledge. It usually does things like "browser hijacks" to redirect your browser to its pop ups, commercials or websites. Spyware can also send information about selections you make on web sites and other media and return that information to a central server.

This was the case with earlier versions of Real Player. People generally consider spyware to be a dirty trick, so today software vendors (who want to protect their reputation) offer to turn on or off information gathering at install.

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Pop Ups

Pop ups are extra browser windows that open automatically as you browse from web page to web page. They are more irratating than dangerous. Today most browser tool bars have pop up killers included as does the later versions of Windows. At their worst pop ups would open many, many windows of commercials over your work space - so fast and numerous that they are impossible to close down before other open. On slower computers, this would grind the system to a halt.

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What is Adware?

Adware is a computer-licensing model that gives you a program to install for free, but send ads to a pane in the newly installed software. The ads can usually be removed by paying for a full license of the software. The once popular Eudora email client was a good example of this.

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What is Phishing?

Before the Internet a person who did "Phishing" would have been called a trickster or con man. Phishing occurs by email. The email generally says something like; "there has been a security breach of your bank account, ebay or paypal account and you have to click here and log in a change your password". See a screen shot of a phish below.

The email generally includes the logo of the alleged sender, say the Westpac Bank or the Commonwealth Bank. The link that you are encouraged to click however goes to a third party domain. Once you log in there of course the trickster has got your account details and can usually change your password and lock you out. Then the onus is on you to prove to your bank you are who you say you are and get your access back.

Phishing Scam - don't be fooled

Don't be fooled. Always open your browser and type your bank's URL to start your banking session. Never click a link supplied to you in email - you will be directed to someone else server.

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