Malware And Its Types

Malware means “malicious software” and is designed to gain access to or install malicious software on a computer without the user’s consent. They perform unwanted actions on the host computer for the benefit of a third party. There is a whole range of malware that can severely degrade the performance of the host machine. There is a whole range of malware that is written just to distract/annoy the user, complex malware that capture sensitive data from the host machine and send it to a remote server. There are different types of malware present on the internet. Some of the popular ones are:

1. Adware: This is a special type of malware that is used for forced advertising. They either redirect the page to an advertisement page or pop-up an additional page that promotes a product or event. These adware are financially supported by the organizations whose products are advertised.

2. Spyware: It is a special type of spyware that is installed in the target computer with or without the user’s permission and is designed to steal sensitive information from the target machine. Mostly it collects the user’s browsing habits and sends it to a remote server without the knowledge of the computer owner. Most of the time they are downloaded to the host computer while downloading freeware i.e. free application programs from the Internet. Spyware can be of different types; it can keep track of the host computer’s cookies, it can act as keyloggers to sniff out banking passwords and sensitive information, etc.

3. Browser Hijacking Software: There are some malicious software which are downloaded along with free software available on the internet and installed in the host computer without the knowledge of the user. This software modifies the browser setting and redirects links to other unknown sites.

4. Virus: Virus is a malicious code written to harm/damage the host computer by deleting or adding a file, occupying the computer memory space by copying the code, slowing down the computer performance, formatting the host machine, etc. It can be spread through email attachments, pen drives, digital images, e-greetings, audio or video clips, etc. The virus may be present in the computer but it cannot activate itself without human intervention. The virus cannot be activated in the host machine unless the executable file (.exe) is executed.

5. Worms: They are a class of viruses that can replicate themselves. They differ from viruses by the fact that they do not require human intervention to travel over the network and spread from the infected machine across the network. Worms can spread either through the network, using operating system flaws or through email. The replication and spread of the worm on the network consumes network resources such as space and bandwidth and forces the network to be blocked.

6. Trojan Horse: Trojan horse is a malicious code that is installed in the host machine by pretending to be useful software. The user clicks on the link or downloads the file that pretends to be a useful file or software from a legitimate source. It not only harms the host computer by manipulating the data but it also creates a backdoor in the host computer so that it can be controlled by a remote computer. It can become a part of a botnet (robot-network), which is a network of computers that are infected with malicious code and controlled by a central controller. The computers in this network that are infected with malicious code are called zombies. Trojans neither infect nor replicate to other computers in the network.

7. Scareware: The Internet has changed the way we talk, shop, play, etc. It has also changed the way criminals target people for ransom. While surfing the Internet, suddenly a pop-up alert appears on the screen warning the user about the presence of dangerous viruses, spyware, etc. in the computer. As a remedial measure, the message suggests that the user download the full paid version of the software. As soon as the user starts downloading, a malicious code, known as scareware, is downloaded to the host computer. It holds the host computer hostage until the ransom is paid. The malicious code can neither be uninstalled nor the computer can be used until the ransom is paid.

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