What is APT?

APT actors differ from opportunistic cybercriminals in sophistication, patience, and target specificity. A criminal group typically automates attacks against thousands of targets and moves on quickly if one does not pay off. An APT actor invests significant resources, custom tooling, original vulnerability research, and detailed reconnaissance of a single organization's people, technology stack, and defenses, and is willing to spend months just establishing a quiet foothold before doing anything that could trigger an alert. Campaigns routinely run for months or years without detection, with the actor periodically checking in on a target rather than immediately pursuing an objective.

Groups are tracked and named independently by government agencies and commercial intelligence vendors, which is why the same actor often carries multiple aliases: APT28 (also called Fancy Bear, tracked to Russian military intelligence), APT41 (a China-linked group known for both espionage and financially motivated operations), and Lazarus Group (linked to North Korea, known for both destructive attacks and cryptocurrency theft) are commonly cited examples. Each tracked group has a documented profile: preferred initial-access methods, custom malware families, typical target sectors, and known infrastructure patterns, maintained and updated as vendors publish new research.

Tradecraft favors stealth over speed. APT actors frequently burn zero-day exploits for initial access specifically because a novel exploit leaves no signature for defenses to catch, and they develop custom malware precisely to evade known-signature detection. Once inside, they lean heavily on living-off-the-land techniques, using built-in OS tools like PowerShell, WMI, and certutil, so their activity blends into normal administrative traffic instead of standing out as obviously malicious. Command-and-control traffic is deliberately low-volume and often mimics legitimate protocols or uses compromised legitimate infrastructure (a hacked small-business website, a cloud storage API) to avoid tripping volume- or reputation-based network detections. Because none of this looks anomalous in isolation, detection depends on behavioral analytics that flag unusual sequences of ordinary actions, dedicated threat hunting rather than waiting on automated alerts, and current intelligence on the specific TTPs of groups likely to target your sector, rather than generic signature matching.