A computer virus is a program that someone has written, like any program it can be executed (that is: Run on your computer.)
The main factor in a virus, like a human virus, it's function is to spread and ‘infect' as many systems as possible. Computer viruses or virii can attach themselves to just about any type of executable file and are spread as files that are copied and sent from individual to individual. Often these attachments come via emails or software downloads.
Many writers of virus code deliberately target certain types of computer users, such as those who download game cracks and serial numbers, pirate software & pirate DVD movies etc
This is to take advantage of the huge amount of traffic and passing along of code these groups do, thereby spreading the virus code faster than anything
Some computer viruses contain a damage routine that delivers the virus payload. While payloads may only display messages or images, they can also destroy files, reformat your hard drive, or cause other damage.
Even if the virus is not destructive it can cause trouble by consuming storage space and memory, and degrading the overall performance of your computer.
There are then different types of virus code. We often see terms like Malware used, so what is Malware? Malware is a malicious piece of code.
Malware performs malicious unexpected or unauthorized actions. It is a general term used to refer to viruses, trojans, and worms. There are so many different actions within malicious codes, the general classification of ‘Malware' is often used to avoid confusion and give a broad term of reference
E.G. A virus that also has Trojan-like capabilities may be called Malware.
What is a Trojan?
A Trojan is Malware that performs a malicious action, but has no replication abilities. Called after The Trojan horse from Greek Mythology, a Trojan may arrive as a seemingly harmless file or application, but actually has some hidden malicious intent within its code.
Trojan Malware usually have a payload. When a Trojan is executed, you may experience unwanted system problems in operation, and sometimes loss of valuable data or even loss of the internet.
What is a worm?
A computer worm is a self-contained program (or set of programs) that is able to spread copies of itself to other computers. The spreadusually takes place via network connections or email attachments.
More recent worms have also discovered ways to propagate using Instant Messengers, via file sharing applications, and by collaborating with other Malware such as Trojans or other worm variants
There are way too many worm type Malware out there to be specific, but to give you an idea of what happens.
Some of the nasty Trojans combine with a worm to attack to system, and spread unknown to you, some worms and trojans can mass-mail copies of the Trojan, and the Trojan downloads copies of the worm. There are families of worms that propagate via an instant messaging application and a popular peer-to-peer file sharing application.
The spreading of virus code & Malware
Malware propagate in a number of ways. Worms may spread via email, instant messengers, or network shares. Viruses replicate within a system, while some viruses also have automatic propagation techniques similar to worms. Trojans. while not having any automatic form of replication and propagation, are nevertheless available all over the Internet, and the links to download them from may be included in email messages, or other Web sites
How do we combat these threats?
Be very selective in what you download, use store bought software when you can, do not accept Fwds and attachments from friends or family, they may have a Trojan and pass it on even without knowing
Never go to crack, pirate or porn sites, these are the most likely source of trouble, be aware of strange pop ups saying you need to download 'xyz' so your computer will run faster, or some strange new plug-in to view a file
If you don't already have a well known virus checker and firewall, please get one soon, they are not expensive and could save you heaps later.
I will not recommend one or the other here, I'll leave it to you to do your homework, not all the big popular names are great so don't believe the marketing hype, go to a few forums that are not sponsored by a antivirus company and ask tech heads what they use and prefer.
Installation of these products are generally easy and with broadband internet connections becoming more common, the time taken to download (automatically) the latest virus signatures and patterns is less than 2 minutes
A short note for the new computer user, a virus signature or pattern mentioned here is NOT a virus, but the virus checkers way of detecting and eradicating the virus when found, these are updated almost daily as new virus codes are found and a solution developed.
We'll leave it there for now and I'll look into the detection and eradication process in a future article
