What is threat hunting in cybersecurity?

Threat hunting is one of the most proactive approaches to cybersecurity—but what does it actually mean, and how does it differ from reactive security monitoring? In this episode of CyberSpeak: A Glossary, we break down threat hunting from the basics to the nuanced approaches that help organizations catch threats before they become full-blown incidents. Learn the difference between IOC sweeps and hypothesis-driven threat hunting, why collaboration makes hunting stronger, and how to move from reactive alerts to proactive security.

Date: March 2026

Featuring:

Ben Baker, Director of Content, Expel

Additional resources

Introduction

Welcome to CyberSpeak: A Glossary, where we break down cybersecurity concepts into clear, actionable explanations. Today’s topic is threat hunting—one of the coolest-sounding practices in cybersecurity and one of the most effective ways to catch threats early.

But first, a joke: I only know 25 letters of the alphabet. I don’t know ‘y’.

Now that we’ve broken the ice, let’s talk about what threat hunting actually means and why it matters for modern security teams.

What is threat hunting?

Ben Baker: Here’s the short version: Threat hunting is a proactive approach to cybersecurity. Instead of waiting for alerts to tell you something’s wrong, you go looking. You dig through your environment to find signs of suspicious behavior—things your existing tools might have missed. It’s part science, part detective work. And it’s how you catch threats early before they become a full-blown incident.

This definition highlights three critical elements:

Proactive, not reactive: Traditional security monitoring waits for alerts. Threat hunting assumes there might already be something wrong and goes looking for it.

Manual investigation: While automated tools support threat hunting, the core activity involves human analysts examining data, forming hypotheses, and following leads.

Early detection: The goal isn’t just to find threats—it’s to find them before they achieve their objectives, whether that’s data exfiltration, ransomware deployment, or lateral movement.

The noise problem in cybersecurity

Ben Baker: Most cybersecurity teams today are drowning in alerts. Between your SIEM and your EDR and your firewall logs and your cloud platforms and blah, blah, blah—it’s a lot. And most of it is noise. And in that noise is exactly where attackers love to hide.

The average security operations center receives thousands of alerts daily. Research consistently shows that the majority of these alerts are false positives or low-priority events that don’t require immediate action. This creates several problems:

Alert fatigue: Analysts become desensitized to alerts when most turn out to be benign, increasing the risk that genuine threats get overlooked.

Resource drain: Triaging endless alerts consumes time that could be spent on more strategic security activities.

Coverage gaps: While analysts chase false positives, real threats slip through unnoticed, often because they’re designed to blend in with normal activity.

Sophisticated attackers exploit this: They understand that security teams are overwhelmed and specifically design their tactics to avoid triggering obvious alerts. They move slowly, use legitimate credentials, and mimic normal user behavior—all techniques that make automated detection more difficult.

Threat hunting addresses this by taking a different approach: instead of reacting to what your tools flag as suspicious, hunters proactively look for what’s unusual, unexpected, or inconsistent with baseline behavior.

The threat hunting process: From hunch to hypothesis

Ben Baker: So threat hunting flips that script. It starts with a hunch—maybe a pattern that doesn’t quite feel right, a weird spike in your network activity, or just a gut feeling that maybe something’s wrong. You know those gut feelings—they’re important to pay attention to.

And then from there, hunters build a hypothesis and test it by combing through raw telemetry logs and behavioral data to either prove or disprove that theory.

This process-driven approach distinguishes threat hunting from random searching. Here’s how it typically works:

Step 1: Develop a hypothesis

Threat hunting begins with a question or suspicion:

“Are there any unauthorized users accessing our cloud storage?”
“Could an attacker be using PowerShell to move laterally?”
“Is there evidence of data staging before exfiltration?”

These hypotheses can come from multiple sources: threat intelligence reports, anomalies noticed during routine monitoring, customer concerns about specific risks, or even just an analyst’s intuition based on experience.

Step 2: Gather relevant data

Once you have a hypothesis, you need data to test it. This typically involves:

Log aggregation from multiple sources (network, endpoint, cloud, identity)
Historical telemetry (often going back 30+ days)
Contextual information about the environment’s normal behavior
Threat intelligence about relevant TTPs

Step 3: Analyze and investigate

This is where the detective work happens. Hunters look for:

Patterns that match the hypothesis
Anomalies that don’t fit normal baselines
Connections between seemingly unrelated events
Evidence of attacker techniques documented in frameworks like MITRE ATT&CK

Step 4: Document findings and take action

Whether the hypothesis is confirmed or disproven, the results inform future security decisions:

If a threat is found: initiate incident response
If nothing is found: document the investigation for future reference and potentially adjust detection rules
Either way: share learnings to improve organizational security posture

Collaboration: The secret weapon of effective threat hunting

Ben Baker: And they don’t do it alone. Threat hunting works best when you’ve got collaboration across multiple parties: your security ops center, your incident response teams, your threat intel folks. Multiple parties. Everyone brings something different to the table between their skill sets and their experiences and their history within the industry. That mix is what makes this process much stronger and more efficient.

Effective threat hunting is inherently collaborative because different teams bring complementary perspectives:

SOC analysts understand day-to-day operations, normal baselines, and what typically triggers alerts in the environment. They know which systems are business-critical and which users have elevated privileges.

Incident response teams bring experience from past breaches and understand how attacks unfold over time. They recognize the subtle signs that distinguish a real compromise from a false positive.

Threat intelligence analysts provide context about current adversary tactics, active campaigns, and emerging threats. They help hunters know what to look for and where attackers are likely to strike.

System administrators and IT teams understand the technical architecture, authorized configurations, and legitimate business processes that might otherwise look suspicious.

When these groups work together, threat hunting becomes far more effective. A SOC analyst might notice unusual behavior, a threat intel analyst might connect it to a known adversary campaign, and an incident responder might recognize it as an early indicator of a technique they’ve seen before.

This collaboration also helps avoid false positives. What looks suspicious to one person might be explained by another’s knowledge of a legitimate business process or recent system change.

Two types of threat hunting: IOC sweeps vs. hypothesis-driven hunting

Ben Baker: Now, depending on who you ask, there are actually two different kinds of threat hunting.

Understanding the distinction between these approaches helps clarify what threat hunting actually involves and when each method is most appropriate.

IOC sweeps: Fast and reactive

Ben Baker: The first is IOC sweeps. This is where you’re looking for known indicators of compromise—things like IP addresses or malware signatures that are tied to active campaigns. It’s fast, it’s reactive, and it’s absolutely useful. However, by the time you’re hunting based on an IOC, that threat might already be in your house. So the benefit can only go so far.

IOC (Indicator of Compromise) sweeps involve searching your environment for known bad:

Malicious IP addresses
File hashes associated with malware
Domain names used in phishing campaigns
Registry keys created by specific threats
Command-and-control (C2) infrastructure

Strengths of IOC sweeps:

Fast to execute with automated tools
Low false-positive rate (you’re looking for specific known threats)
Valuable for confirming whether known campaigns have affected your environment
Can be triggered by threat intelligence feeds or vulnerability disclosures

Limitations of IOC sweeps:

Reactive by nature—you’re hunting for threats that have already been identified
Attackers can easily modify IOCs (change IP addresses, create new malware variants)
Won’t catch novel threats or attacks customized for your organization
Limited value against sophisticated adversaries who customize their tools

IOC sweeps are essential security hygiene, but they’re only one part of effective threat hunting.

Hypothesis-driven threat hunting: Slow, thoughtful, and tailored

Ben Baker: The second is what we like to call capital T, capital H “Threat Hunting.” It’s slower, it’s more thoughtful, and way more tailored.

At Expel, this is where we really try to stand out. Let’s say a customer comes to us and says, “Hey, I’m worried about this part of my environment. I don’t have proof that something’s going wrong, but something feels off.” That’s where we roll up our sleeves and start digging.

We’ll often go back 30 days in telemetry and just start asking questions: What’s normal? What’s weird? What’s different now compared to last week? And that’s where the good stuff lives. It’s not just about searching for a specific threat, it’s about noticing the blip on the radar that doesn’t really belong, and then following that thread until we understand why it’s happening.

Hypothesis-driven threat hunting is fundamentally different in approach:

It’s environment-specific: Instead of looking for generic IOCs, hunters investigate behaviors and patterns unique to your organization’s environment, technology stack, and risk profile.

It’s question-driven: Hunters start with questions like:

“Are there any accounts showing signs of compromise?”
“Is anyone accessing systems they don’t typically use?”
“Are there signs of reconnaissance or lateral movement?”
“What’s happening with our most sensitive data?”

It requires deep investigation: This isn’t a quick scan—it’s a thorough examination of telemetry, logs, and behavioral data that might span weeks or months of activity.

It catches what automated tools miss: Because hypothesis-driven hunting looks for unusual patterns and context-specific anomalies, it can identify threats that don’t match any known signatures or rules.

Ben Baker: It takes longer. It’s more nuanced, but our customers really value it. Why? Because it’s tuned to their environment. It’s not just a general list of threats that are making headlines.

This tailored approach is particularly valuable for:

Organizations with unique or complex environments
High-value targets that sophisticated adversaries specifically research
Situations where there’s a concern but no concrete evidence
Post-incident validation to ensure threats are fully eradicated
Proactive security for organizations with mature security programs

Why proactive threat hunting matters

Ben Baker: So why does this more proactive approach matter? Because today’s attackers, again, they’re hiding. They’re not smashing through the front door. They’re not the Kool-Aid man. They slip in quietly. They stay hidden and wait. They’re stealthy, which means we have to be persistent. We have to be creative. And honestly, we have to be a little paranoid.

Modern cyber attacks have evolved significantly from the opportunistic, noisy breaches of the past. Today’s threat landscape is characterized by:

Dwell time: The average time between initial compromise and detection can span weeks or months. During this time, attackers quietly move through networks, escalate privileges, and position themselves for maximum impact.

Living off the land: Sophisticated attackers use legitimate system tools (PowerShell, Windows Management Instrumentation, remote desktop protocols) to avoid detection. These activities don’t trigger malware alerts because they’re using approved software.

Credential abuse: Rather than deploying malware, many attacks rely on stolen credentials to access systems. To automated tools, a compromised account looks identical to a legitimate user.

Low and slow movement: Attackers intentionally move slowly and blend in with normal activity to avoid triggering anomaly detection systems.

Advanced persistence: Modern attackers establish multiple footholds in an environment so that even if one access point is discovered and closed, they maintain access through others.

Ben Baker: That’s why modern security can’t just be reactive. It has to be proactive. It has to hunt.

This shift from reactive to proactive security represents a fundamental change in mindset:

Reactive security assumes your tools will catch threats as they occur. It waits for alerts, responds to incidents, and focuses on known threats.

Proactive security assumes threats may already be present in your environment. It actively searches for signs of compromise, investigates anomalies, and prepares for novel attacks.

Organizations with mature security programs understand that both approaches are necessary. Automated detection and response handle the high-volume, known threats. Threat hunting addresses the sophisticated, stealthy attacks that automated systems miss.

How Expel approaches threat hunting

Ben Baker: And if you’re looking for a partner who does both the IOC sweeps and the customized hypothesis-driven work, we’d love to show you how we do it at Expel.

Expel’s threat hunting approach combines both methodologies to provide comprehensive coverage:

Continuous IOC monitoring: We automatically hunt for known threats across all customer environments, leveraging threat intelligence feeds and our own research to identify active campaigns that might affect our customers.

Custom hypothesis-driven hunts: When customers have specific concerns, we conduct tailored investigations that go deep into their unique environments. These hunts often span 30+ days of telemetry and focus on answering the specific questions that keep security leaders up at night.

Collaborative approach: Our hunters work directly with customer security teams, bringing external expertise while leveraging internal knowledge about the organization’s normal operations and risk priorities.

Learning and improvement: Each hunt—whether it finds a threat or not—generates insights that improve detection rules, inform security roadmaps, and strengthen overall security posture.

Proactive communication: We don’t wait for customers to ask for hunts. Our team proactively identifies opportunities where hunting could reduce risk or address emerging threats relevant to specific industries or technologies.

This combination ensures that customers benefit from both the speed of automated IOC detection and the depth of customized, human-driven investigation.

Getting started with threat hunting

For organizations looking to implement or improve their threat hunting capabilities, consider these foundational steps:

Build a strong data foundation: Effective threat hunting requires comprehensive visibility. Ensure you’re collecting and retaining logs from:

Endpoints (EDR telemetry)
Network traffic
Cloud infrastructure and SaaS applications
Identity and authentication systems
Critical applications

Develop baseline understanding: Before you can identify anomalies, you need to understand what’s normal in your environment. Document typical user behaviors, system communications, and operational patterns.

Start with structured hunts: Begin with hypothesis-driven hunts focused on specific questions or concerns rather than aimless searching. Use frameworks like MITRE ATT&CK to guide your investigations.

Foster collaboration: Break down silos between SOC, incident response, threat intelligence, and IT teams. Create processes for sharing findings and coordinating investigations.

Invest in skill development: Threat hunting requires a mix of technical skills, investigative thinking, and security knowledge. Provide training and opportunities for analysts to develop these capabilities.

Measure and improve: Track metrics like threats discovered, false positive rates, time to detection, and lessons learned. Use these insights to refine your hunting process over time.

Consider partnerships: Many organizations benefit from combining internal security teams with external expertise. Managed threat hunting services can provide specialized skills, broader threat intelligence, and additional capacity.

Frequently asked questions about threat hunting

What’s the difference between threat hunting and threat detection?

Threat detection is automated—your security tools continuously monitor for known bad behaviors and alert when they see matches. Threat hunting is manual and proactive—analysts actively search for threats that automated systems might miss, often based on hypotheses about what could be wrong rather than confirmed indicators. Detection is reactive; hunting is proactive.

How often should organizations conduct threat hunts?

This depends on organizational risk, resources, and maturity. High-risk organizations might hunt continuously or weekly, while others might conduct formal hunts monthly or quarterly. At minimum, organizations should hunt after major security events, when deploying new technologies, or when threat intelligence suggests relevant campaigns are active. Mature programs integrate hunting into routine security operations rather than treating it as a periodic activity.

Do you need special tools to do threat hunting?

While specialized threat hunting platforms can help, the most critical requirement is comprehensive visibility—good log collection, retention, and analysis capabilities. Many organizations successfully hunt using SIEM platforms, EDR tools, and data analytics platforms they already have. The limiting factor is usually analyst skill and time rather than tooling. That said, platforms that support hypothesis testing, data visualization, and collaborative investigation can significantly improve efficiency.

What skills do threat hunters need?

Effective threat hunters combine several capabilities: deep understanding of attacker tactics and techniques (frameworks like MITRE ATT&CK), proficiency with log analysis and data querying, knowledge of operating systems and network protocols, familiarity with forensics and incident response, curiosity and investigative thinking, and strong communication skills to document and share findings. Many successful hunters come from SOC analyst, incident response, or penetration testing backgrounds.

Can small organizations do threat hunting?

Yes, though the approach may differ from large enterprises. Small organizations might conduct focused hunts monthly rather than continuously, prioritize high-risk areas rather than comprehensive coverage, leverage managed threat hunting services to supplement internal capabilities, or participate in information sharing communities to benefit from collective intelligence. The key is starting with whatever resources you have rather than waiting until you can build a dedicated hunting team.

How do you measure threat hunting success?

Success can be measured through several metrics: threats discovered that automated tools missed, reduced dwell time for detected incidents, false positive rates (lower is better for IOC hunts), security improvements implemented based on hunt findings, time from hypothesis to conclusion, and analyst skill development over time. However, remember that not finding threats during a hunt is also valuable—it provides confidence that your environment is clean and validates your existing security controls.

What’s the difference between threat hunting and penetration testing?

Penetration testing simulates attacks to identify vulnerabilities and weaknesses in your defenses—it’s offensive security testing whether your controls work as intended. Threat hunting assumes attackers may have already bypassed those defenses and searches for evidence of actual compromise—it’s defensive investigation looking for real threats in your environment. Pen testing is proactive validation; threat hunting is proactive detection.

Key takeaways

Threat hunting represents a critical evolution in cybersecurity—from purely reactive defense to proactive threat discovery:

Reactive security alone isn’t enough: Sophisticated attackers design their tactics to evade automated detection. Proactive hunting helps catch what your tools miss.

Two complementary approaches: IOC sweeps provide fast, focused searches for known threats. Hypothesis-driven hunting enables deep, tailored investigations of potential compromises.

Collaboration amplifies effectiveness: The best threat hunting combines expertise from multiple disciplines—SOC analysts, incident responders, threat intelligence, and IT operations.

It’s a process, not a tool: While technology supports hunting, the core activity involves human analysts forming hypotheses, investigating anomalies, and following leads to their conclusion.

Start where you are: You don’t need a dedicated hunting team or specialized tools to begin. Start with the data and capabilities you have, focus on high-priority concerns, and build from there.

Continuous improvement: Each hunt—whether it finds threats or not—generates insights that strengthen your overall security posture through improved detections, better baselines, and enhanced analyst skills.

Modern cyber threats demand modern security approaches. As attackers become stealthier and more patient, defenders must become more proactive and persistent. Threat hunting bridges the gap between automated detection and the sophisticated, targeted attacks that automated systems struggle to catch.

For more cybersecurity terms and concepts explained, visit expel.com/cyberspeak. To learn how Expel’s threat hunting services combine IOC sweeps and hypothesis-driven investigations to protect your organization, reach out to our team today.

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