ELI5: What is Threat Hunting?

Most alarms wait for a burglar to trip them. But a threat hunter is more like a detective who goes looking for trouble before the alarm even rings. They walk through the building checking closets, looking behind doors, and following suspicious footprints — not because an alarm went off, but because they have a hunch something might be wrong. If they find anything, they can stop the bad guy before real damage is done.

Overview

Threat hunting is the proactive, human-driven process of searching through networks, endpoints, and datasets to identify threats that have evaded automated detection systems. Unlike reactive alerting, threat hunting assumes the network may already be compromised and seeks to find evidence of adversary activity. It requires skilled analysts who form hypotheses and test them against available telemetry.

Key Concepts

  • Hypothesis-driven hunting: Starting with an educated guess about attacker behavior and searching for evidence to confirm or deny it
  • Intelligence-driven hunting: Using threat intelligence reports, IoCs, or known TTPs as starting points
  • Baseline-driven hunting: Identifying deviations from known-good baselines in network traffic, process execution, or user behavior
  • MITRE ATT&CK framework: Knowledge base of adversary tactics, techniques, and procedures (TTPs) used to structure hunts
  • Data sources: EDR telemetry, SIEM logs, network flow data, DNS logs, authentication logs
  • Indicators of Attack (IoA): Behavioral indicators that suggest an active attack in progress (more proactive than IoCs)
  • Advisary emulation: Simulating known threat actor behavior to test detection capabilities
  • Hunt maturity model: Levels from HM0 (initial, relies on automated alerts) to HM4 (leading, creates new detection content)
  • theHarvester: OSINT tool for gathering emails, subdomains, hosts, and names from public sources
  • dnsenum: DNS enumeration tool for discovering DNS records and subdomains
  • Nessus: Commercial vulnerability scanner for identifying security weaknesses
  • Cuckoo Sandbox: Open-source automated malware analysis system that runs suspicious files in isolated environments

Exam Tips

Remember

Threat hunting is PROACTIVE (you go looking), not reactive (waiting for alerts). It requires skilled humans — you cannot fully automate hunting. Think of it as “assume breach and go find it.”

  • Threat hunting often results in new detection rules being added to the SIEM
  • Know the difference: threat hunting (proactive search) vs. incident response (reactive to alerts)
  • MITRE ATT&CK is the most common framework referenced for structuring threat hunts

Connections

Practice Questions

Scenario

See case-threat-hunting for a practical DevOps scenario applying these concepts.