Introduction
Automated tools catch known patterns. Capable attackers know that, so they work below the thresholds: valid credentials, built-in admin tools, techniques nobody has written a rule for yet.
Proactive cyber threat hunting is the analyst-led practice of searching for that hidden activity before an alert fires.
SANS's 2026 hunting survey found that only 40% of programs formally measure hunting effectiveness, and that 50% name data quality or quantity as the main barrier.
This article covers methods, the hunt workflow, best practices, and how managed detection and response (MDR) can supply hunting capacity you don't have in-house.
Key Takeaways
- Hunting finds threats your detection tools missed. It complements SIEM, EDR, and incident response.
- Strong hunts start with a specific, testable hypothesis.
- A hunt with no confirmed attacker still exposes telemetry gaps and weak controls.
- MDR can supply hunters, but verify that hunting is a core service.
What Is Proactive Cyber Threat Hunting?
The UK's NCSC describes hunting as the "proactive, iterative and human-centric identification of cyber threats that have evaded existing security controls." It works from an assumption that an attacker may already be inside, or that existing controls don't cover every technique. That is a working assumption, not a claim that you are compromised.
Reactive Detection, Threat Hunting, and Threat Intelligence
These three functions get confused. They do different jobs:
- Detection: rules and analytics raise alerts for analysts to triage.
- Hunting: analysts test a hypothesis against your own telemetry.
- Threat intelligence: analyzed information about adversaries, campaigns, and techniques that supports decisions.
Intelligence can inform a hunt, but it never proves a threat exists in your environment. A report that a group abuses scheduled tasks tells you what to look for. Only a search of your logs tells you whether it happened.
Indicators of Compromise and Indicators of Attack
An indicator of compromise (IOC) is an artifact tied to a breach, such as a malicious file hash, IP address, or domain. DeepSeas documents this kind of IOC for tools like HandleKatz and NanoDump, which are published as MD5 hashes.
An indicator of attack (IOA) describes behavior: abnormal credential use, privilege escalation, lateral movement. IOAs can include post-access activity, so don't treat them as strictly "before compromise."
Behavioral IOAs help hunters find novel or fileless activity. IOCs remain useful for scoping an incident and for retrospective searches across historical logs.
Why Proactive Threat Hunting Matters
Living-Off-the-Land Techniques Evade Rules
Attackers misuse PowerShell, remote administration tools, scheduled tasks, and valid accounts because that activity looks normal. In the SANS 2026 survey, 73% of respondents named living-off-the-land methods as the top technique of nation-state actors, and 63% said the same of organized crime. These are respondent assessments, not shares of all attacks.
A documented example: a CISA advisory on Volt Typhoon describes actors repeatedly exfiltrating domain credentials and using native tools such as PowerShell, net, wmic, and ntdsutil. They also tested domain-joined OT assets with default vendor credentials.
The advisory recommends reviewing application logs and IT-to-OT access logs, which is exactly the kind of search a hunt performs.
Staying Below Alert Thresholds
Slow lateral movement, low-volume data access, and activity spread across systems rarely trip a single rule. Hunters look for related behavior across time and data sources. That is how dwell time shrinks.
Hunting also sits outside the alert queue. It can examine low-confidence signals and events that look benign alone but become suspicious when correlated across:
- Identity systems
- Endpoints
- Network traffic
- Cloud workloads
Business Impact of Earlier Discovery
Mandiant's M-Trends 2026 reports a global median dwell time of 14 days across 2025 investigations. Cyber-espionage and North Korean IT-worker incidents each had 122-day medians, so the overall figure does not apply to every threat type.
Earlier discovery shrinks the window for lateral movement, data theft, and ransomware deployment. Speed matters: DeepSeas notes that earlier Trigona ransomware incidents ran roughly 2.5 hours from compromise to execution. In one DeepSeas-handled case, the attack was detected and blocked before data loss or encryption.
How Does a Threat Hunt Work?
Published frameworks such as Splunk's PEAK (Prepare, Execute, Act) follow a common sequence.
Start With a Specific Hypothesis
"Look for bad stuff" isn't a hunt. A usable hypothesis names the suspected technique, affected users or assets, time range, and expected observable.
Example: "An attacker replayed a stolen session token against our finance users in the last 30 days. We should see a session ID persist while the user-agent changes."
Good inputs include:
- MITRE ATT&CK techniques
- Sector-specific intelligence
- Recent vulnerabilities and prior incidents
- Low-confidence alerts
- Major environmental changes
ATT&CK is a taxonomy of adversary behavior, not a prescribed workflow. DeepSeas analysts use it to build hypotheses around lateral movement, credential access, and command-and-control.
Scope the Hunt and Select Data
Define systems, identities, cloud accounts, network segments, critical assets, and a time window before querying. Then confirm you have the telemetry. Joint logging guidance from ASD's ACSC with CISA, FBI, and NSA points to:
- Endpoint process creation, command-line auditing, and PowerShell logs
- Authentication events, user and session identifiers
- Cloud control-plane operations and permission changes
- Remote access, network metadata, and edge devices
Missing or poorly normalized logs can make reliable conclusions impossible. Timestamps should be consistent, ideally UTC, and storage should be protected.
Search, Correlate, and Pivot
Search for the initial observable, then correlate related events across sources. Pivot from an identity to a device, process, connection, cloud resource, or data access event.
Microsoft's investigation of Storm-2755 shows the pattern. Sign-in telemetry showed a session's user-agent changing to Axios while the session ID stayed the same, which indicates token replay. Follow-on hunts looked for inbox rules hiding messages and changes to payment information.
Confirm, Close, or Escalate
Separate malicious behavior from legitimate admin activity, document the evidence trail, and classify the outcome:
- Confirmed threat activity
- Benign activity
- Inconclusive
- Visibility gap
Confirmed findings go to incident response and containment through established procedures. Inconclusive ones should state what extra telemetry or validation is needed.
Turn Results Into Improvements
Hunt outcomes feed detection engineering: new rules, tuned analytics, updated playbooks, control fixes, and asset inventory corrections. DeepSeas turns validated hypotheses into detection rules deployed across every monitored environment.
A hunt that finds nothing still pays off if it validates coverage, exposes a logging gap, or closes an untested attack path.
Proactive Threat Hunting Best Practices
- Document every hunt. Record hypothesis, scope, data sources, queries, assumptions, findings, decision, owner, and follow-ups so another analyst can reproduce it.
- Prioritize by your threat profile. Weigh sector-targeted adversaries, exposed assets, privileged identities, cloud adoption, third-party access, acquisitions, and IT/OT convergence over generic hunt libraries.
- Measure outcomes, not activity. Track completed hunts, confirmed threats, visibility gaps, detection improvements, remediation progress, and time to validate.
- Respect privacy and operational boundaries. Get documented authorization, apply access controls and retention rules, and limit exposure to sensitive data.
Where HIPAA applies, HHS's minimum-necessary standard requires reasonable limits on how protected health information is used and accessed. Not every provider automatically qualifies as a business associate, so confirm agreements before sharing data.
In OT environments, NIST SP 800-82r3 notes that passive monitoring adds no network traffic, while active scanning can cause instability or safety impacts. Use extreme caution, offline testing, and planned outages where possible.
How MDR Supports Proactive Threat Hunting
When MDR Makes Sense
Gartner describes MDR as remotely delivered, "AI-augmented, human-led, turnkey, modern SOC functions." It fits when:
- You have no 24/7 in-house SOC
- Analysts are buried in alert triage
- You lack specialized hunting skills
- Your environment is regulated or distributed
Staffing is a real constraint. In ISC2's December 2025 workforce study, 33% of respondents reported insufficient resources to adequately staff their teams. 79% of SOCs run 24/7 per the SANS 2025 SOC survey, but round-the-clock operation doesn't prove continuous proactive hunting.
What Genuine MDR Hunting Looks Like
Genuine MDR hunting includes:
- Human-led hypotheses backed by threat intelligence
- Access to endpoint, network, identity, and cloud telemetry
- Scheduled and situational hunts
- Documented findings and clear escalation procedures
- Feedback loops into detection engineering
Ask vendors:
- How often do hunts run, and who decides the topics?
- What are the analysts' qualifications?
- Which data sources are supported?
- How is hunting tailored to my environment?
- What do reports contain, and who owns response?
- How do findings improve detections?
Automation helps by collecting and correlating data, prioritizing leads, and running repeatable searches. Analysts still provide context, challenge assumptions, validate findings, and decide on escalation.
The DeepSeas Approach
DeepSeas combines proactive threat intelligence and hunting with 24/7 Managed Detection and Response through its CyberFusion SOC. Analysts use both structured, hypothesis-driven and unstructured, analytics-led methods. Telemetry from EDR, SIEM, and cloud sources is centralized in one platform.
Coverage is customizable and works with existing tools, including Splunk and Sentinel, so there's no rip-and-replace. It suits organizations that want complete cyber defense without building an internal hunting function. Teams evaluating MDR can review DeepSeas MDR capabilities or request a security assessment.
Connecting Hunting to Broader Defense
Hunting shouldn't be an isolated periodic exercise. A good engagement links it to incident response, offensive security, strategic advisory, and governance, risk, and compliance, with measurable improvement over time.
Frequently Asked Questions
What are the key differences between threat hunting and threat intelligence?
Threat intelligence supplies context about adversaries, campaigns, and techniques. Threat hunting applies that context to search your own telemetry for evidence of malicious activity.
What is the difference between IOA and IOC?
An indicator of attack is suspicious behavior or an attack pattern. An indicator of compromise is an artifact associated with a compromise. Mature programs use both.
What is proactive threat hunting?
It is the active, hypothesis-driven search for threats that haven't triggered existing alerts. Hunters rely on behavioral evidence, threat intelligence, and environmental telemetry.
How does proactive threat hunting differ from threat detection?
Detection identifies activity through configured rules or analytics. Hunting starts the search independently to find what those controls may miss.
How often should threat hunting be conducted?
Run it continuously or on a recurring schedule matched to risk. Base frequency on the risks you face, including threat intelligence, major vulnerabilities, and environmental changes, rather than one annual exercise.
Do organizations need an in-house threat hunting team, or can MDR provide it?
MDR can provide specialized hunters and continuous SOC capability. Verify that hunting is a customer-specific core service, not occasional alert triage.
