Trojans – myths & facts

  • October 7, 2002
  • 3 min read

Not so long ago, the more knowledgeable PC users were well aware of the risks that computer viruses posed. Only a few years later, almost every PC user is aware of the very-real dangers that a virus can pose. Many of us use some form of anti-virus software, and a reasonable number of us diligently keep the anti-virus definitions up to date.

Only a complete novice would question the need for good anti-virus software today. However many users do not realise that these programs may actually provide their users with a false sense of security. One common mistake is to assume that anti-virus software automatically means that your system is secure. It isn’t. Most anti-virus applications deal specifically with one thing – viruses. They don’t protect your system from intruders, and they don’t ensure that other software that you may use is secure and legitimate.

Another very dangerous assumption that many users of anti-virus software make, is that their anti-virus application will also keep their systems clear of trojans. Not so. In order to understand this, let’s take a step back.

Despite the fact that they are often confused, viruses and trojans are two very different things. A virus by definition makes copies of itself and spreads, in much the same way that it’s biological namesake will do among hosts. A trojan on the other hand, also known as a trojan horse, is simply a program that pretends to be something else.

So why are trojans or trojan horses so dangerous? The basic idea is that you download a program, for example one that you think is some sort a game demo. When you run the demo, to your surprise, nothing happens. Or so you thought.

What may have happened is that you’ve just unwittingly run some form of program that has planted itself on your hard drive. Perhaps it’s going to be a very basic application, and simply delete some files on your system. Perhaps it’s an even more sinister tool that will actually give other people full access to your hard drive and system. Sounds ridiculous? It happens literally every single day, to computer users all around the world.

Whether the trojan you just unwittingly downloaded and installed will delete files from your system, open your web connection to snoopers, share your emails or simply watch everything that you do, one thing’s for sure. You don’t want it there.

And the terrifying fact? You may want to be sure that you’re sitting down here. Most anti-virus applications will not protect your system from trojan horses. Why? Well the real question is why should they? As explained, a virus and a trojan are two very different things. Getting a shot from a Doctor against the flu won’t protect you from being hit by a bus after you leave the surgery. Other preventative measures are required.

So in the above scenario of the user downloading what they think is a game demo, they may even scan the file with their anti virus software, and receive the all clear. Why? Because the file isn’t infected with a virus. The anti-virus software isn’t saying that the software is safe to install, it isn’t saying that it won’t make a mess of your system files, and most importantly, it isn’t saying that it doesn’t contain a trojan or trojan horse.

In short, if you want to keep your PC safe, follow the three golden hints.

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Have a Great (Malware-Free) Day!



Emsisoft founder and managing director. In 1998 when I was 16, a so called 'friend' sent me a file via ICQ that unexpectedly opened my CD-ROM drive, which gave me a big scare. It marked the start of my journey to fight trojans and other malware. My story

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