performing-insider-threat-investigation

name	performing-insider-threat-investigation
description	Investigates insider threat incidents involving employees, contractors, or trusted partners who misuse authorized access to steal data, sabotage systems, or violate security policies. Combines digital forensics, user behavior analytics, and HR/legal coordination to build an evidence-based case. Activates for requests involving insider threat investigation, employee data theft, privilege misuse, user behavior anomaly, or internal threat detection.
domain	cybersecurity
subdomain	incident-response
tags	["insider-threat","user-behavior-analytics","data-exfiltration","privilege-misuse","DFIR"]
mitre_attack	["T1078","T1048","T1567","T1114"]
version	1.0.0
author	mahipal
license	Apache-2.0
nist_csf	["RS.MA-01","RS.MA-02","RS.AN-03","RC.RP-01"]

Performing Insider Threat Investigation

When to Use

• DLP (Data Loss Prevention) alerts on large data transfers to personal cloud storage or USB devices
• User behavior analytics (UBA) detects anomalous access patterns for a user account
• HR reports a departing employee suspected of taking proprietary information
• A privileged user is observed accessing systems outside their job function
• Whistleblower or coworker report alleges policy violations or data theft

Do not use for external attacker investigations where compromised credentials are used without insider collusion; use standard incident response procedures instead.

Detection Gaps & Validation

• Low-and-slow beats threshold alerts: the most-missed insider drips data out under DLP limits — 20-50MB/day to personal webmail or a sanctioned cloud tenant over weeks, rather than one big USB dump. Baseline each user's 3-6 month normal (volume, destinations, hours) and alert on sustained deviation, not a single large transfer.
• Authorized access ≠ authorized use: insiders use legitimate credentials, so signature/IOC detection sees nothing. Validate intent by correlating what was accessed against job function (UEBA peer-group anomaly), access timing (after-hours/post-resignation), and staging behavior (mass reads, zip/rar creation, renaming to innocuous extensions).
• Cover every exfil vector, not just the alerting one: USB, personal webmail, OneDrive/GDrive/Dropbox sync clients, browser uploads, print jobs, screenshots, AirDrop/Bluetooth, and phone-camera capture of screens. A clean DLP log only rules out the channels DLP inspects — confirm with endpoint sync-client logs, print logs, and badge data.
• Cross-corroborate before accusing: pair behavioral anomaly with content evidence (the actual file, its classification) and a timeline (Git clone logs, USN Journal, cloud activity API). One signal is a lead; a corroborated timeline is a case. Compare against the documented baseline to avoid flagging a genuinely busy quarter as theft.
• FP tuning / preserve admissibility: scope monitoring to legal-approved subjects and exclude sanctioned bulk workflows (backups, data-migration roles). Don't tip off the subject, hash and chain-of-custody all evidence, and image the endpoint before the last day — an untested assumption of guilt collapses without preserved, reproducible evidence.

Prerequisites

• Legal counsel approval before initiating any monitoring or investigation of an employee
• HR partnership with defined investigation procedures and employee privacy guidelines
• DLP platform with content inspection and policy enforcement (Symantec DLP, Microsoft Purview, Digital Guardian)