Trojan horse

nounverified·updated May 9, 2026

GlossaryL1 — what DictionaryL2 — how used ThesaurusL3 — relations Universaleverything

A computer program that appears to have a useful function, but also has a hidden and potentially malicious function that evades security mechanisms, sometimes by exploiting legitimate authorizations of a system entity that invokes the program.

MWESANS Glossary of Security Terms

Senses

4 more senses beyond the canonical

ISACA Cybersecurity Glossary

Purposefully hidden malicious or damaging code within an authorized computer program Scope Note: Unlike viruses, they do not replicate themselves, but they can be just as destructive to a single computer.

Federal Financial Institutions Examination Council (FFIEC) IT Examination Handbook Infobase, Glossary

Malicious code that is hidden in software that has an apparently beneficial or harmless use.

Wordset Dictionary

a program that appears desirable but actually contains something harmful

NIST SP 800-171r3attested usage pack match

No definition is given in NIST SP 800-171r3. The term is attested in use at 2 citations in that document; a definition is pending curation.

Classifications

per-axis with provenance

Entity Type

Threat90%rule-basedr:entity.threat.attack.v1

?unassignedlast reviewed —

Sensitivity

unclassified

Information Class

unclassified

Variants

6 surface forms

synonym: fifth columntrojan
alternatephrasing: Trojan Horse
plural: Trojan horses
possessive: Trojan horse's
pluralpossessive: Trojan horses'

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