Malware

Malicious software or malware is an umbrella term used to describe any type of software, program, etc. that is installed on the system without the user’s consent and knowledge. It is designed to harm or corrupt the programs, files, information, etc. on the system of the host. 

Computer viruses, worms, trojan horses, spyware, ransomware, scareware, adware, and other malicious programs come under the category of malware. 

• Viruses

These are the malicious programs that spread across systems and programs. They cause disruption to systems, operational problems like reduced speed, pop-up windows, crashing of devices, changes to default settings, etc., and damage the data as well as software. They attach themselves to an executable host file. Now, when the host file is opened the virus becomes active. The most important aspect of a virus is that it is able to replicate itself. 

• Worms

They do not need to attach themselves to the host files. They themselves are software that can replicate on their own and spread through the systems.

 

• Trojans or Trojan Horse

These are also software that deceive the host into believing that they are legitimate but in reality, they run malicious activities on the systems. These also help the attacker establish a backdoor. They cannot replicate themselves.

 

• Spyware

It is a program which collects information about the user, it’s computer, it’s internet browsing, the documents downloaded by the user, payment details etc.  and sends this data to the hacker. This is used to steal passwords, money etc. Keyloggers are examples of spyware.

• Ransomware

This is a version of malware that blocks/denies access to the victims to files/data on their own computer/system by either locking the screen, or encrypting files etc. They then ask for a ransom in order to give the access again or the decryption key(in case of crypto ransomware).

• Scareware

This aims at tricking the user to believe that some files of the system have been corrupted. This is done by using fake pop-ups. These would repeatedly come on the screen until the user is forced to click on some option like ‘Remove all threats’ or to download their fake antivirus software. This antivirus would not be the legitimate one but would implant some other kind of malware into the victim’s computer. 

  

• Adware

It is also known as advertising-supported software. It is a type of software which pop-ups adverts usually within a web browser. They collect the user’s browsing history to pop up ads that are tailored based on our interests. These get on to a victim's computer through free softwares downloaded from the internet or may be inserted by a hacker. These are used for advertising purposes and adware creators make their money from third parties via Pay-per-click or Pay-per-view or Pay-per-install.