Malware
Malware can be defined as any unintended and unsolicited installation of software on a system without the user knowing or wanting it.
Types of Malware
There are many types of malware, but for our purposes, the following list of malware will suffice.
Virus
A virus is a parasitic program that attaches itself to another program in order to infect that program and perform some unwanted function. Viruses range in severity and in the threat they pose. Some are easy to detect and remove from a system, whereas others are very difficult to detect and remove. Some viruses use polymorphic (changing)technology to morph as they move from system to system, thereby prolonging their
detection. A virus requires users to assist it by launching the application or script that contains the virus. The users may not know they have executed a virus; they may instead think they are opening an image or a seemingly harmless application.
Trojan Horse
A Trojan horse is a malicious piece of software that performs a nefarious deed on behalf of an attacker without the user knowing it is there. As the name implies, some Trojan horses make their way onto a system embedded within another piece of software.
Pirated software has been known to contain Trojan horse code.
Worms
Simply put, worms are self-propagating viruses. They require no action on the user’s part to execute and move from system to system. In recent years worms have been prevalent and have been used for many purposes, like distributing Trojan horses and other forms of malware.
Spyware/Adware
Spyware and adware describe the class of software that is installed without a user’s knowledge in order to report the behavior of the user to the attacker. The attacker in this
case may be working under the guise of an advertiser, marketing specialist, or Internet researcher. Besides the obvious privacy issues here, in most cases, this class of software is not malicious. However, there are some forms of spyware that use key-logging technology to capture user keystrokes and siphon them off the machine into a central database. In that case, passwords and financial information may be gathered and that
spyware should be considered a high threat to the user or organization.
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