Among the most notorious kinds of malware are viruses and worms. “Computer viruses” is the term that is used for a program that has infected some executable program and that is the reason that when you run one, the spread of the virus can infect other executable files. The virus also may contain content that performs other actions which are often risky and dangerous. A worm on the other hand, is a program that actively transmits itself to the network with the sole purpose of infecting other computers.
Malicious programs are those that are used to infiltrate or cause damage to a computer without the permission of the owner. Malware is not to be confused with damaged programs. Those are programs that have a legitimate use but contain harmful bugs. Malware is any program designed to cause issues with using a regular computer. Malware, running as privileged code can be used to damage computer systems. “Computer Virus” is often and regularly used in the media industry in describing different types of malware. Another word used to describe malware is “badware”.
Some antivirus programs are not able to terminate malware or Trojans on your computer that use what is called a virus chest file to get into places where they do not belong. Tools such as rootkits permit concealment by changing the underlying operating structure so that malicious programs are hidden from the user. Some malware software installs keyloggers which logs the keystrokes of the user when entering passwords, credit card numbers and other information that might be useful to the creator. It is then forwarded to the creators of the malware automatically, which allows credit card theft and other fraud. Most systems contain bugs which can be used by malware. New adware programs have specific response mechanisms against known malware protection and to help prevent them from running or being installed. Some software can even delete them automatically.
This definition leads to the observation that the virus requires input from a user in order to spread, whereas worms spread automatically. Using this distinction, worms transmitted by email or text documents which depend on recipients opening various files or email to infect a computer should be called viruses rather than worms.
In a broader sense, Trojan horses are basically programs that utilize computer users to unknowingly hide malicious or harmful content. The impact may occur immediately and may lead to unintended consequences, such as deletion of user files, or installation of further malicious or unwanted material. Trojans are often used to start a worm outbreak by introducing the worm on the user’s local network.
For malicious programs to accomplish their goals, they should be able to work unnoticed or they will be deleted by the user or administrator of the computer operating system. Obscuring their identities may also help in getting the malware installed on the system in the first place. If a malicious program masquerades as something harmless or desirable, users may be tempted to use it having no idea what they were doing.
Among the more popular ways that adware is disseminated is as a Trojan horse that comes bundled with a program that is common and desirable that a user simply downloads from the net. If users install the program, adware is installed along with it.