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Overview
An insider threat is a security risk that originates from within an organization — from individuals who already have authorized access and misuse their privileges. Insider threats are particularly dangerous because these individuals are trusted, operate within normal access patterns, and understand internal systems and security controls well enough to avoid detection.
Terminology
| Term | Definition |
|---|
| Insider Threat | A security risk posed by individuals with authorized access to an organization’s systems or data |
| Malicious Insider | An insider who intentionally seeks to cause harm, steal data, or disrupt operations |
| Negligent Insider | An insider who unintentionally causes harm through carelessness or lack of security awareness |
| Compromised Insider | A legitimate insider whose credentials have been stolen and are being used by an external attacker |
| Insider Kill Chain | The progression of stages an insider threat moves through from motivation to concealment |
| Privilege Abuse | Using legitimate access for unauthorized or harmful purposes |
Core Concepts
Types of Insider Threats
| Type | Description | Example |
|---|
| Malicious Insider | Intentionally seeks to cause harm, exfiltrate data, or disrupt operations | Disgruntled employee stealing customer data before resignation |
| Negligent Insider | No malicious intent but causes harm through carelessness or lack of awareness | Clicking a phishing link or misconfiguring a production system |
| Compromised Insider | External attacker uses stolen credentials to impersonate a legitimate user | Credential stuffing attack that succeeds against an employee account |
Insider Kill Chain
The progression of stages an insider threat moves through:
| Stage | Description |
|---|
| Motivation | The trigger — financial stress, grievance, ideology, coercion, or recruitment by external actor |
| Planning | Identifies what to target and what outcome is desired |
| Preparation | Positions access, gathers credentials, and prepares tools |
| Execution | Carries out the action — exfiltration, sabotage, fraud, or providing access to outsiders |
| Concealment | Covers tracks using insider knowledge of logging systems and security monitoring |
Why Insiders Are High Risk
- Already trusted with legitimate access — significantly less scrutiny than external connections
- Operate within normal behavior baselines, making anomaly detection harder
- Know which controls exist and what to avoid
- Compromised insiders appear identical to legitimate users in logs
- Can operate undetected for extended periods
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