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Now that flu season is upon us and we spend more and more time indoors in an attempt to escape the chills of the cold weather outside, many of us start spending a lot more time on our computers. While you are sipping your hot chocolate and surfing the web, be careful that while you are staying clear of a cold you computer doesn’t catch one. This week, we’ll talk about computer viruses, what they do and how to avoid them.
Computer viruses can range from something as simple as the Common Cold all the way up to Ebola. Some viruses do not even cause any real harm to a computer—they simply exist to replicate themselves on as many other computers as possible. In other words, a virus might not delete any files from your computer at all, instead it just sits there taking up system resources to try and make sure it infects other computers. Other, more malignant, viruses can send nasty emails to everyone in your address book and then completely wipe out your hard drive.
Basically, what is commonly called a computer ‘virus’ falls into one of three categories: viruses, worms and Trojan horses. Note that worms and Trojan horses are not viruses per se, though they can be just as destructive. Since the popularity of the web and email, traditional computer viruses are not nearly as common as they used to be. Instead, most often when someone refers to a ‘virus’, they really mean a worm or a Trojan horse. We’ll discuss each type briefly.
A computer ‘virus’ is a computer program that attaches itself onto another computer program in a PC. These can be spread by sharing floppy disks or CD/DVD disks between users. Viruses can also attach themselves to files on a network so that when someone accesses the file their computer becomes infected. When the virus is activated, usually by the user opening the infected file, it does its dirty work. Many viruses are set on a time delay so that they simply copy themselves to other computers until a preset date and time, for example January 1st. When that date occurs, all computers with that virus will then be wiped clean, play a song, show a nasty image on the screen, or do whatever the virus programmer wanted to happen. These sorts of date-based viruses are called time bombs.
Worms are very similar to traditional computer viruses except they are self-contained. In other words, they do not attach themselves to other computer programs; they are themselves complete programs that can exist as a simple file on the computer. Though a worm can infect computers through various means, the most common method is email. Commonly, a worm will look in the user’s email address book and send an email to every person with an attachment containing a copy of the worm. The famous Melissa and ILOVEYOU viruses are examples of worms.
Trojan horses are named very appropriately. Consider the mythical battle of Troy, where the Greeks hid in a huge wooden horse. The Trojans took in the horse as a battle trophy to celebrate their ‘defeat’ of the Greeks, had a big party, got drunk and went to bed. While the Trojans were sleeping off their wine, the Greeks crawled out of the horse and overtook the city of Troy. A Trojan horse virus is just that: it looks like a nice, safe piece of software, but when you open it you get infected with a virus. A Trojan horse virus cannot replicate itself, though it may be spread by the use of a worm. Most often they are sent as email attachments. Usually, you can only be infected if you open the attachment in the email. This is a crucial point: if you get an email from a friend with an attachment that looks suspicious, ask them if they meant to send it to you before clicking and opening the attachment.
How do you protect yourself and your computer from these nasty viruses? It’s actually quite simple, really. The best and most effective way to keep your computer healthy is to always have a virus protection program running on your computer. Also, never open email attachments or downloaded files that look suspicious.
Now, for the Cool Site of the Week... This week’s featured site is Clamwin.com. There are a few antivirus software programs you can buy that will keep you safe, but these cost money up-front for the software and then you must buy a yearly subscription to keep the virus list up to date. ClamWin is antivirus software that is absolutely free. It features automatic updates to keep you current on all the latest viruses as well as email scanning. Before you spend money on an antivirus software package, you may want to try this one for free.
As always, if you have any questions or suggestions for future articles, please email me at mike@MikeBryant.com. |