Types of Malware


Malware is a word formed by merging parts of two words: malicious software.

It is basically a programming code written specifically for some form of cyber attack.


All kinds of cyber criminals use malware for stealing personal informations, financial data and intellectual property. The consequences of those attacks are cyber espionage, illegal incomes, physical destruction…

Most common mechanism of malware infection:

  • Directly from Internet
  • Email attachment
  • Phishing – email frauds

There are lots of malware types such as:

  • virus – modifies files by adding malicious executable code, 
  • worm – stand alone executable program, replicates itself from one computer to another
  • trojan –  pretends to be legitimate program, it can instal additional malware like backdoor
  • backdoor/trapdoor – allows remote access to infected computer, user is not aware 
  • logic bomb – unwanted and unknown executable code inserted in valid applications, that activates when certain logical conditions are fulfilled, 
  • time bomb – type of logic bomb, activates in predefined moments like on 1. april or Friday the 13th 
  • rabbit – replicates itself nonstop, overload resources, one type of Denial of Service attack,
  • espionage software (spyware) – reaches the system with the help of Trojan, collects user information such as screenshots, keyboard input, form data that the user fulfills, credit card information…
  • keylogger – type of spyware, remembers keyboard inputs
  • rootkit – software for obtaining admin actions on a system, allows concealment of presence,
  • botnet – network of “hacked” computers, members of network are called “zombies”, used for DoS (Denial of Service) attacks
  • ransomware – coding files on victims hard drive and asking for money in exchange for a key to decode files

Of course, there are many other types of malware that are constantly being improved over older versions, and each version has its own subvariants.

There are lots of ways to defend against malware and one of them is anti-malware software.

Anti-malware is software for detecting threats and weaknesses.

Most common functions of anti-malware software are: 

  • installation in the operating system, 
  • detecting worm, trojan or other types of malicious software before “infection” – based on signatures,
  • cleaning infected computer after “infection” – special boot-up tools,
  • scanning email attachments and removing the ones who are malicious,
  • on-the-fly analysis of Internet content,
  • detection of outdated software that can have weaknesses

    Examples: Avast, ESET, Kaspersky, Symantec…