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Understanding the Threat to Your PC
No one who uses the Internet is free from the spectre of virus infection. Just connecting to the Internet without the appropriate security software can leave you vulnerable to infection. It seems that hackers and virus writers are constantly finding new security holes to exploit and use to infect users' PCs, whether it is to cause damage to the PC itself, steal data from it, or spy on what the user is doing. It is therefore essential that you implement a strategy for preventing and dealing with virus infections if you are to keep your PC in a workable state. This ranges from using firewall and anti-virus software to configuring Windows to be as secure as possible. This article will show you all of the steps that you need to take to build a virus-free Windows system.
What is a Virus?
Today the term malware is commonly used to describe all different kinds of malicious software that can infect your computer to steal data, purposefully cause damage, or launch attacks on other computers. A virus is a type of malware, along with Trojans, worms and Spyware The following section describes the different types of malware that can infect your PC:
Spyware
Recently Spyware has become a common problem for Windows PC users. In contrast to viruses and worms, Spyware cannot self-replicate and infect systems automatically. Generally, Spyware is bundled as part of other free software, such as peer-to-peer file sharing programs.
Worms
Worms are malicious programs that duplicate and distribute themselves using local area networks (LANs) and the Internet. Worms typically spread through email, instant messaging, peer-to-peer file sharing programs and by exploiting security vulnerabilities in Windows or other software running on your PC. Very often a worm will be designed to conduct some malicious activity, such as deleting files on your hard drive.
Worms may also include so called 'back doors' which leave holes open on your computer for further infection by other
malicious programs, or actively downloads other malicious programs from the Internet to infect the host computer. The key difference between a virus and a worm is that a worm can propagate itself, whereas a virus requires some kind of 'host' to transmit it.
Viruses
A classic virus works by inserting itself into the code of another program, so that it is run when the host program is executed. It spreads in a similar way to a biological virus, which inserts itself into living cells. Viruses can be destructive, or merely annoying, for example, by displaying a message on a certain date.
A virus can also use a document that can contain scripts as a host, such as Word documents that use Visual Basic for Applications (VBA) scripts. A virus can replicate itself, commonly by copying itself on to a floppy disk in an infected system and then infecting any systems that the disk is inserted into. Nowadays, the meaning of the term virus has become broader to cover much of the behaviour of worms.
Trojans
By analogy with the story of the Trojan horse, a Trojan in computing terminology is a malicious program that is disguised as something else. While the program may have some useful function, it also has other secret, undesired, functions that the user does not know about. The difference between a Trojan and a virus is that a Trojan does not replicate itself, but instead fools a user into running it by posing as something else.
