# Advanced Persistent Threat (APT)

A sophisticated, well-resourced attacker, often state-sponsored, that maintains long-term stealthy access to a target network.

An **Advanced Persistent Threat (APT)** refers to a sophisticated, well-funded attacker, often a nation-state or organized criminal group, that gains unauthorized access to a network and works to maintain long-term, stealthy presence rather than causing immediate, obvious damage. The goal is usually sustained espionage, data theft, or positioning for a future attack.

APT groups are patient, using custom tools, careful evasion techniques, and multiple footholds to avoid detection for months or even years. Defending against them requires continuous monitoring and threat hunting[↗](/threat-hunting) rather than relying solely on perimeter defenses, since a determined APT will eventually find a way past a static wall.