1. A generic term used to describe malicious software such as viruses, Trojan horses, spyware, and malicious active content. (, accessed 15 Nov 2010).

2. [Malicious] software such as viruses or Trojans designed to cause damage or disruption to a computer system. (AFDD 3-13).

3. Malicious software that secretly accesses a computer system without the owner's informed consent. A general term to mean a variety of forms of hostile, intrusive, or annoying software or program code, including computer viruses, worms, Trojan horses, spyware, most rootkits, and other malicious software or program. (Wikipedia).

Source: Terms & Definitions of Interest for DoD Counterintelligence Professionals, Office of the National Counterintelligence,

3. Comes from the terms "malicious" and "software". Generic term for software which carries out harmful functions on a computer. This comprises amongst others viruses, worms, Trojan horses.

Source: Information Assurance Situation in Switzerland and Internationally, Reporting and Analysis Centre for Information Assurance MELANI,

4. Software or firmware intended to perform an unauthorized process that will have adverse impact on the confidentiality, integrity, or availability of a system. For example, a virus, worm, Trojan horse, or other code-based entity that infects a host. Spyware and some forms of adware are also examples of malware.

Source: Election Terminology Glossary - Draft, National Institute of Standards and Technology (NIST),

5. Malicious software; software designed to interfere with a computer’s normal functioning (e.g., viruses, Trojan horses, spyware) (Merriam-Webster).

Source: Independent Panel on Internet Voting, British Columbia,

6. Malicious types of software such as adware, spyware, viruses.

Source: An Investigation into Foreign Entities Who Are Targeting Servicemembers and Veterans Online, Vietnam Veterans of America,

7. Software that compromises the operation of a system by performing an unauthorized function or process.

Source: Explore Terms: A Glossary of Common Cybersecurity Terminology, National Initiative for Cybersecurity Careers and Studies (NICCS),

8. A computer program that is clandestinely placed onto a computer with the intent to compromise the privacy, accuracy, or reliability of the computer’s data, applications, or operating system.

Source: U.S. Cyberspace Solarium Commission, March 2020,