Computer Viruses and Malware – What Are They?

I often get asked what is a computer virus, how does it differ from a worm or Trojan and how do they get into my computer? Please find below my article, giving you a brief explanation of these terms and how easily they can infect your system.

What is a Computer Virus?

Computer viruses are annoying at best and can be extremely destructive at worst. A computer virus is a piece of code which can attach itself to one of your files or programs, enabling it to spread to other computers infecting as it goes. This causes damage to files, software and hardware.

Computer viruses can range in severity in the same way as an organic virus. With an organic virus, unless kept in complete isolation, it usually spreads through human interaction. The difference is, (other than the obvious) a computer virus needs human interaction to enable it to spread, such as sending an email or sharing a file.

What is a Worm?

Similar to a virus, a worm is designed to copy itself across computers, but the horror is that it does this automatically.

It does this by taking control of features on a computer that transport files and information. Once on your system they have the ability to replicate in great numbers, very quickly. One of the things that they are famous for, is sending out copies to everyone in your address book and if the recipient is unaware, it will do the same to theirs.

They have the potential to cause heavy traffic, clogging networks and in extreme cases slowing down the entire internet.

So if you are waiting twice as long for pages to load, this could well be a possible cause.

What is a Trojan?

As in the Trojan horse of Greek mythology, which appeared to be a gift, but actually contained soldiers, Trojans appear to be useful software. Unfortunately, they often arrive as an email attachment, usually appearing to be from a legitimate source, but when opened lead to a trail of destruction. They can also be present in free software that you may download, so beware!

What is Malware?

Malware is a term that is used to describe “malicious software” programs. The things that are included in this are spyware, adware, and cookies.

What is Spyware and Adware?

It has been estimated that 90% of all computers on the internet are infected with some type of spyware.

Spyware refers to programs that can use your internet connection to send information, normally without your permission or knowledge, to another computer. The information that it then gathers could be a record of your browsing habits. This can include things that you have downloaded and even personal information such as your name and address.

There are different types of spyware which perform different functions. Some may change your home page, producing pop up personal ads, even if you are not online, and may even high-jack your browser, taking you to an unexpected site. Spyware that serves you personalized ads is also known as adware.

Some free software or programs have spyware included. Some of the more legitimate programs mention in their terms and conditions, that they may gather information, although most people do not tend to read this. However, spyware does not have to come bundled in a program. It is most commonly installed surreptitiously, often in the form of a pop up, or asking you to install a plug in, to enable you to display the site correctly. Spyware can use the local resources of your computer, such as processor and memory power, as well as some of your internet bandwidth.

So if your computer:

  • slows to a crawl
  • if you click on a link to a site and you end up at another site, due to your browser having been hijacked,
  • you enter a search and received an unexpected result
  • you get pop up ads that address you by name from a site that you haven’t visited
  • you click on your home page and it takes you to a new site and when you try and switch back the same site appears again,

Then you probably have been infected with some form of Malware.

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