A combination of the words “malicious” and “software” describes “malware” quite succinctly. Malware,is software developed for the purpose of doing harm.The term “malware” derives it’s definition from the intention of the person creating it and not from the software itself. The software cannot be termed “malicious” or “evil” unless it is used for a purpose which the creator intends to hurt someone or someone’s computer. The purpose of software relies upon the person creating it.
Malware can be classified based on how they get executed, how they spread, and what they do. The classification is not perfect, however, in the sense that the groups often overlap and the difference is often not obvious.
There are five types of malware out there today:
(1) Contagious Software. This type of software is composed of computer viruses or so-called worms. This type of malware is the most common. A “virus” describes a computer virus rather than an actual physical virus which may infect us. Viruses are different than worms in their distribution and in the actual operation.
The first type of malware to evolve was the computer virus. Viruses work and spread within the infected system by attaching themselves to other software. In the case of macro viruses, to documents. During the execution of the program the viral code is executed. Viruses spread across computers when the software or document they attached themselves to is transferred from computer to computer.
Back in the day when I was a young man, just getting into computers and trading floppy disks back and forth, you could count on a virus being on a disk once in awhile. A virus copies itself into an executable file and will run whenever a certain program is activated or a certain hard disk is opened.
The computer worm, used to infect systems, began when the internet was first used.The worm scans different networks in the computer, testing for any vulnerable systems where it can copy itself. From this new base, inside your computer the worm begins scanning and copying itself to all vulnerable files or processes. Although worms and viruses had distinct meanings and uses, they now are used to indicate any type of contagious malware.
Computer worms are stand-alone software and thus do not require other pieces of software to attach themselves to. They are started as part of the boot process. Worms spread, either by exploiting some vulnerability of the target system, or by using some kind of social engineering to trick users into executing them.
(2) Hidden files. This type of malware is used to hide any type of activity within a user’s computer. There are various types of hidden files, such as:
(a) A Trojan. These are the familiar trojan horses. They serve the same purpose as the mythical trojan horse. You know, the one the Greeks used to take over Troy. Some trojans are registered on your computer in the form of utilities. When the user downloads the malware, a door opens for other types of malware to be introduced into the system.
Trojan horses are get executed by being part of an otherwise useful piece of software. Trojan horses are attached to the host software manually, they cannot infect other pieces of software the way viruses can, nor can they replicate themselves. Trojan horses rely on the useful features of the host software, which trick users to install them. One of the most insidious types of Trojan horse is a program that claims to rid your computer of viruses but instead introduces viruses into your computer.
The devious mind that creates the virus and plants it successfully will see a massive computer outbreak of the virus. By introducing the virus into one network via a trojan horse, the creator sees the spread of the virus to other networks.
(b) A Backdoor. A Backdoor is a piece of software that allows access to the computer system, bypassing the normal authentication procedures. This virus creates an alternative doorway inside your structure. It creates a different pathway or route to the goodies. This virus circumvents any security system residing on your computer. Once inside the system via the backdoor, the hacker will be able to do anything they want to do.
There are two groups of backdoors. The first group works much like a Trojan. 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.
(3) For Profit Malware. There are some disreputable companies out there who will increase their profits any way they can. This malware comes in the form of a dialer. A dialter is the type of malware which goes through your internet connection, rerouting your net connections through an expensive phone line. This increases your bill that you have to pay.A computer that has this malware is forced to call the compliant phone line and run up a huge bill.
(4) An Exploit. A piece of software that attacks a particular security vulnerability. Exploits are not necessarily malicious in intent – they are often devised by security researchers as a way of demonstrating that a vulnerability exists. However, they are a common component of malicious programs such as network worms.
(5) Phony or Hoax Viruses. There are instances where hoax virus warning messages have been sent which suggest that the recipient may have a particular virus, together with helpful instructions about how to confirm and eliminate the virus. These messages almost invariably tell you to look for a particular file and if it is present, delete it. In most cases the file which they mention is a Windows system file which if deleted, will cause serious running problems. If in doubt, run an internet search on Google for the filename, and you will almost certainly find information about it, and any recent scam.
So there you have it. Five kinds of malware that will cause you headaches unless you have an anti-virus program that looks out for your computer.