xalgord 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
Detection Gaps & Validation
- Network logs alone miss the highest-signal exfil. SIEM-only hunting overlooks USB mass copy (Security 6416 PnP device, Microsoft-Windows-DriverFrameworks-UserMode 2003/2102), local printing, and photographing the screen. Add removable-media and DLP telemetry.
- Personal-cloud exfil blends with sanctioned use. Uploads to personal OneDrive/Gmail/Dropbox look like normal SaaS traffic on raw byte volume. You need a CASB/proxy with per-user behavioral baselines, not a global threshold.
- Low-and-slow staging under daily limits evades volume rules — aggregate reads per user over weeks and correlate with HR signals (resignation notice, PIP, role change).
- Off-hours must be per-user. A single org-wide "after 6pm" rule drowns shift workers and global teams in false positives; use individual UEBA baselines instead.
- Privileged abuse looks authorized: admins reading HR/finance shares are "in their rights." Monitor 4663 object-access on sensitive shares (with SACLs in place) and 4662 on AD objects to spot scope creep.
- Validate the rule fires: as a test account, copy a large benign file set to USB and to a personal cloud account, and confirm 4663/6416 and the DLP/CASB event are generated and alert.
- Tune false positives: backups, OneDrive/Box sync clients, and CI/dev builds generate bulk reads. Allowlist service accounts and known sync processes before alerting.
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
Output Format
Hunt ID: TH-DETECT-[DATE]-[SEQ]
Technique: T1078
Host: [Hostname]
User: [Account context]
Evidence: [Log entries, process trees, network data]
Risk Level: [Critical/High/Medium/Low]
Confidence: [High/Medium/Low]
Recommended Action: [Containment, investigation, monitoring]