Excel Formula For Number Of Days From A Certain Date All About Computer Viruses

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All About Computer Viruses

Your computer is slow as molasses. Your mouse freezes every 15 minutes, and the Microsoft Word program doesn’t seem to open.

You may have a virus.

What exactly is a virus? What kind of computer do you have? How did it get there? How is it spreading and causing such havoc? And why bother with your computer anyway?

Viruses are pieces of programming code that copy, or copy, themselves inside your computer without your express written permission to do so. Forget getting your permit on paper. Viruses don’t even bother to ask for your permission! Very aggressive.

In comparison, there are pieces of code that can be duplicated inside your computer, that your IT guy thinks you need. But the code spreads, perhaps across your office network, with your consent (or at least your IT guy’s consent). These types of replicating codes are called agents, said Jimmy Kuo, a research fellow at McAfee AVERT, the research arm of anti-virus software-maker McAfee Inc.

In this article, though, we’re not talking about the good guys, or agents. We will talk about bad guys, viruses.

Long, long ago computer years, like five, most viruses were of the same breed. They probably got into your computer via an email attachment or a floppy disk (remember those?). Then they attach themselves to one of your files, say your Microsoft Word program.

When you opened your Microsoft Word program, the virus replicated itself and attached itself to other files. These can be other random files on your hard drive, files removed from your Microsoft Word program, or other files, depending on how the virus writer wants to treat the virus.

This virus code can contain hundreds or even thousands of instructions. When it replicates, it inserts those instructions into the files it infects, said Kerry Nachenberg, chief architect at Symantec Research Labs, an arm of antivirus software-maker Symantec. Corporation

Because many types of viruses now exist, the type just described is called a classic virus. Classic viruses still exist but are not as prevalent as they once were. (Perhaps we can put the classic viruses on the shelf with Hemingway and Dickens.)

Nowadays, in the modern age, viruses are spread through web browsers, files shared on the Internet, emails themselves, and vulnerabilities in computer networks.

As far as web browsers are concerned, Microsoft’s Internet Explorer takes most of the heat for spreading viruses because it is used by more people for web surfing than any other browser.

However, “any web browser potentially has vulnerabilities,” Nachenberg said.

For example, let’s say you visit a website in IE that you have every reason to think is secure, Nachenberg said.

But unfortunately it is not. It has virus code lurking in the background that IE won’t protect you from. While you’re browsing the site, the virus is downloaded to your computer, he said. This is one way to catch a bad virus.

Over the past two years, another popular way to catch viruses has been through downloads that computer users share with each other, often on music sharing sites, Kuo said. On Limewire or Kazaa, for example, teenagers or other music enthusiasts may think they’re downloading that latest Justin Timberlake song, when in fact they’re downloading a virus onto their computer. It’s easy for a virus writer to put a download containing a virus on one of these sites because everyone is sharing it with everyone anyway.

Here’s one you might not have thought of. If you use Outlook or Outlook Express to send and receive email, is there a preview pane below the list of emails that shows the contents of the email you’ve highlighted? If so, you may be putting yourself at risk.

Some viruses, though a small percentage according to Nachenberg, are inserted directly into emails.

Forget to open the attachment. All you have to do is look at an email to potentially get a virus, Kuo added. For example, have you ever opened or seen an email that says “Loading”? Well, once everything is “loaded”, the virus in the email can be loaded onto your computer.

So if I were you, I’d click View on the toolbar of your Outlook or Outlook Express and close the Preview pane. (You’ll need to click View and then Layout in Outlook Express.)

Network at work? This is how you can get a virus. Worms are viruses that get into your computer through networks, Kuo said. They travel from machine to machine and, unlike classic viruses, they attack machines rather than individual files.

The bugs live in your working memory, or RAM, Nachenberg said.

Okay, so we’ve talked about how viruses get on computers. How do they do so much damage once they get there?

Let’s say you’ve caught a classic virus, which replicates and attacks various files on your computer. Let’s go back to the example of the virus that initially infected your Microsoft Word program.

Well, it could eventually cause that program to crash, Nachenberg said. It can also damage your computer as it tries to infect new targets.

This process of infecting targets and finding new ones can eventually use up your computer’s processing power, he said.

Often the destruction caused by a virus is pegged to a specific event or date and time, called a trigger. For example, a virus can be programmed to remain dormant until January 28th. When that date rolls around, though, it might be programmed to do something as harmless but annoying as splash popups on your screen, or something as serious as a hard reformat of your computer. Drive, Nachenberg said.

There are other possible reasons, though, such as a virus causing your computer to act slowly or strangely. And this leads us to a new section – the reason why virus writers want to waste their time creating viruses in the first place.

Most viruses are still teenagers looking for some notoriety, Nachenberg said. But a growing segment of the virus-writing population has other objectives in mind.

For these other purposes, we first need to explain the “backdoor” concept.

The sole purpose of some viruses is to create a vulnerability on your computer. Once it creates this kind of hole, or back door, it indicates the home of the mama or grandpa virus writer (as in ET). Once a virus writer gets the hint, they can use and abuse your computer as they please.

Trojans are sometimes used to open back doors. In fact, that’s usually their sole purpose, Kuo said.

Trojans are pieces of code that you can download to your computer from, say, a newsgroup. As in the Trojan War as they are named, they are usually disguised as innocuous pieces of code. But Trojans are not considered viruses because they do not replicate.

Now back to the actual viruses. Let’s say we have Joe Shamo the virus writer. He sends a virus that infects a thousand machines. But he doesn’t want feeds in his case. So he instructs viruses on different machines to send their signals to an undetected location rather than his own computer. Hotmail email is an example of such a place, Kuo said.

OK, so virus writers now control these computers. What will they use them for?

One use is to send spam. Once that backdoor is open, they bounce spam off those computers and send it to other machines, Nachenberg said.

That’s right. Some of the spam in your email may have been sent to other innocent computers before it reached you so that it could remain disguised. If authorities could track down the original senders of spam, they could crack down on the spam itself. Spammers don’t want that.

Ever heard of phishing emails? Those are the ones that are supposed to be from your internet service provider or bank. They usually request some information from you, such as your credit card number. The problem is, they’re not from your Internet Service Provider or your bank. They are from evil people after your credit card number! Well, these emails are often sent as spam, by sending them through innocent computers.

Of course, the manufacturers of antivirus software use different methods to combat the attack of viruses. Norton, for example, uses signature scanning, Nachenberg said.

Signature scanning is similar to the process of finding a DNA fingerprint, he said. Norton examines programming code to determine what viruses are made of. It adds those bad instructions it finds to a large database of other bad code. Then it uses this huge database to search and match the code in it with the same code on your computer. When it finds such virus code, it lets you know!

©2004 by Kara Glover

Feel free to reprint this article in newsletters and websites, including a resource box. If you use this article, please send me a short message telling me where it appeared: kara333@earthlink.net

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