Malware: spyware, adware, viruses and trojans

Maleware: spyware, adware, viruses, trojan horses, malicious dialers and other nasties are the current scourge of the Internet.

Is your computer running slow? Do pop up windows frequently annoy you (even at times when you are not logged on? Does your dial up connection suddenly pop up out of nowhere and you didn't click on it? Has your start page suddenly changed? Chances are very good that you are the victim of malware.

Even if none of these things happen to you, you'ld be surprised at what you might find lurking on your computer!

What is it?

Malware (short for "malicious software") is any software developed for the purpose of doing harm to a computer system.

The threat of malicious software can easily be considered as the greatest threat to Internet security. Earlier, viruses were, more or less, the only form of malware. Nowadays, the threat has grown to include network-aware worms, trojans, spyware, adware and so on.

There are many different types of Malware:

• Viruses & Worms: Spread through e-mail, web pages or networks, these can self replicate and spread to other computers. They can often cause great damage to a computer
• Trojan Horse: A trojan horse program is a harmful piece of software that is disguised as legitimate software. Trojan horses cannot replicate themselves, in contrast to viruses or worms. A trojan horse can be deliberately attached to otherwise useful software by a programmer, or it can be spread by tricking users into believing that it is useful. To complicate matters, some trojan horses can spread or activate other malware, such as viruses. These programs are called droppers.
• Back Door: A backdoor is a piece of software that allows access to the computer system bypassing the normal authentication procedures. Based on how they work and spread, there are two groups of backdoors. The first group works much like a Trojan, i.e., they are manually inserted into another piece of software, executed via their host software and spread by their host software being installed. The second group works more like a worm in that they get executed as part of the boot process and are usually spread by worms carrying them as their payload.
• Spyware: Spyware consists of computer software that gathers information about a computer user (such as browsing patterns in the more benign case or credit card numbers in more serious ones) and then transmits this information to an external entity without the knowledge or informed consent of the user.
• Adware: Adware or advertising-supported software is any software application in which advertisements are displayed while the program is running. These applications include additional code that displays the ads in pop-up windows or through a bar that appears on a computer screen.

Every computer that connects to the Internet should have a good virus-scanner and spyware/adware scanning software installed on it and these should be used regularly to scan the system to rid it of malware.