Types of Malicious or Malware Software

Malicious software is any software designed to harm a system and network. It comes in many forms. This tutorial explains the malicious software you should be familiar with for entry-level certification programs such as CCNA and CompTIA Network Plus.

Malicious software is also known as malware. A hacker can distribute it in many ways. For example, he can attach it to an email. When the user downloads the mail attachment, it also downloads and installs to the system. Another popular way to share it is to use pirated software. He can hide the malware inside pirated software and share the infected software via illegal software-sharing sites. When a user downloads and installs the infected software, the malware also automatically installs.

Types of malware

There are many types of malware or malicious software. They are classified based on their distribution methods and functions. You should know the following malware types for any entry-level certification program.


A virus attaches to a file. When you open the file, it activates and infects your system. It can delete files from the system or modify the boot sector so the computer no longer boots.


A worm is a self-replicating virus. It doesn’t need another application or human interaction to propagate. It arrives as attachments, instant messages, or through pirated software. It can also reside on a USB drive that infects the system when the user connects it to the computer. It infects one computer and then spreads across your entire network.


A trojan disguises itself in another application. When you install the application, it installs with the application and silently listens for the commands from the creator. Typically, it opens a TCP/IP port that allows the hacker to connect to the system and take control.


Spyware monitors and collects information about you and your Internet surfing habits. In addition, it can also make changes to the system through browser redirection or slowing down the network connection.

types of malware


Adware automatically loads advertisements on the user screen in the form of pop-up windows. The advertisements attract the user to purchase products or subscribe to particular websites.

Logic bomb

Logic bomb installs in the system but does nothing until a specific condition is satisfied, such as a particular date or time. When the defined condition matches, the virus performs its malicious purpose.


A keylogger captures all of your keystrokes and sends them to the hacker. The hacker uses this data to learn about your passwords and other confidential information.


Spam is unsolicited commercial mail. Spam messages typically are mass-mailed, and their purpose is to convince you to purchase their products or services. The spammers usually get your email address from a website or newsgroup after you have posted a comment to the group.


Ransomware takes control of your system and does not give control back until you pay a fee. For example, it can encrypt your drive, and you must pay a fee to get the encryption key.

ComputerNetworkingNotes CCNA Study Guide Types of Malicious or Malware Software