What is What is Trojan Malware??

What is Trojan Malware?

malware OpenTrojan Team Updated 2026-08-20

A Trojan is malware disguised as legitimate software. Learn how Trojans work, how to detect them, and how to protect yourself.

Quick Answer

A Trojan is malware disguised as legitimate software. Unlike a virus it does not self-replicate, but it can open backdoors, steal data, or install additional malware.

Definition

A Trojan (Trojan horse) is malicious software that disguises itself as a legitimate program to trick users into installing it, after which it can open backdoors or steal data.

Overview

A Trojan is malicious software disguised as a legitimate program. The name comes from the Greek story of the Trojan horse.

How it works

Executes under a trusted appearance.
May open a backdoor for remote control.
May download and install additional malware.
Often used to steal credentials and data.

Key difference from a virus

A Trojan does not self-replicate; it requires a user to install or execute it. A virus can spread on its own.

Detection & defense

Use reputable antivirus/EDR and keep definitions updated.
Verify file hashes before installation (see the Hash Checker tool).
Download software only from official sources.
Be cautious with attachments and cracked software.
Run regular scans and monitor for unexpected processes or outbound connections.

Malware Intelligence

References

https://www.cisa.gov/topics/cyber-threats-and-advisories

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