Detect insider threat behavioral indicators including unusual data access, off-hours activity, mass file downloads, privilege abuse, and resignation-correlated data theft. Use when proactively threat-hunting for malicious or negligent insider activity, or when investigating a departing or disgruntled employee for potential data theft.
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Use detecting-insider-threat-behaviors to develop a threat-hunt plan for [hypothesis] using the available EDR, SIEM, Sysmon, and Windows event telemetry; provide detection queries, correlation guidance, false-positive validation, and response recommendations.
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[hypothesis]
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SKILL.md
name: detecting-insider-threat-behaviorsdescription: Detect insider threat behavioral indicators including unusual data access, off-hours activity, mass file downloads, privilege abuse, and resignation-correlated data theft. Use when proactively threat-hunting for malicious or negligent insider activity, or when investigating a departing or disgruntled employee for potential data theft.domain: cybersecuritysubdomain: threat-huntingtags: - threat-hunting- mitre-attack- insider-threat- data-theft- ueba- proactive-detectionversion: '1.0'author: mahipallicense: Apache-2.0d3fend_techniques: - Restore Access- Password Authentication- Biometric Authentication- Strong Password Policy- Restore User Account Accessnist_csf: - DE.CM-01- DE.AE-02- DE.AE-07- ID.RA-05mitre_attack: - T1046- T1057- T1082- T1083
Detecting Insider Threat Behaviors
When to Use
When proactively hunting for indicators of detecting insider threat behaviors in the environment
After threat intelligence indicates active campaigns using these techniques
During incident response to scope compromise related to these techniques
When EDR or SIEM alerts trigger on related indicators
During periodic security assessments and purple team exercises
Prerequisites
EDR platform with process and network telemetry (CrowdStrike, MDE, SentinelOne)
SIEM with relevant log data ingested (Splunk, Elastic, Sentinel)
Sysmon deployed with comprehensive configuration
Windows Security Event Log forwarding enabled
Threat intelligence feeds for IOC correlation
Workflow
Formulate Hypothesis: Define a testable hypothesis based on threat intelligence or ATT&CK gap analysis.
Identify Data Sources: Determine which logs and telemetry are needed to validate or refute the hypothesis.
Execute Queries: Run detection queries against SIEM and EDR platforms to collect relevant events.
Analyze Results: Examine query results for anomalies, correlating across multiple data sources.
Validate Findings: Distinguish true positives from false positives through contextual analysis.
Correlate Activity: Link findings to broader attack chains and threat actor TTPs.
Document and Report: Record findings, update detection rules, and recommend response actions.
Key Concepts
Concept
Description
T1078
Valid Accounts
T1530
Data from Cloud Storage Object
T1567
Exfiltration Over Web Service
Tools & Systems
Tool
Purpose
CrowdStrike Falcon
EDR telemetry and threat detection
Microsoft Defender for Endpoint
Advanced hunting with KQL
Splunk Enterprise
SIEM log analysis with SPL queries
Elastic Security
Detection rules and investigation timeline
Sysmon
Detailed Windows event monitoring
Velociraptor
Endpoint artifact collection and hunting
Sigma Rules
Cross-platform detection rule format
Common Scenarios
Scenario 1: Employee downloading bulk files before resignation
Scenario 2: IT admin accessing HR data outside job function
Scenario 3: Service account used for unauthorized data queries
Scenario 4: Contractor copying source code to personal cloud storage