Trojan

A Trojan (or Trojan horse) is malware disguised as legitimate software. Unlike viruses and worms, Trojans don't self-replicate — they rely on tricking users into installing them by appearing to be useful programs, documents, or updates. Once installed, a Trojan can give attackers remote access, steal data, install additional malware, or perform other malicious actions.

Trojans are commonly delivered through phishing emails with attachments, fake software download sites, or malicious links. Remote Access Trojans (RATs) are particularly dangerous because they give attackers full, hidden control of compromised systems.

Why It Matters

Trojans often bypass basic security controls because users willingly install them. Application whitelisting, email filtering, and user training — all CMMC requirements — work together to prevent Trojan infections in your environment.