Insider threats are among the most challenging security problems. The attacker has legitimate access, knows your systems, and blends into normal activity. But the approaches used to detect insider threats can easily cross ethical and legal boundaries if not implemented carefully.
The privacy tension
Thorough user monitoring can detect insider threats effectively. It can also create a surveillance environment that damages trust, morale, and potentially violates data protection regulations like UK GDPR.
The question is not whether to monitor, but how to monitor proportionately. Security teams need approaches that detect genuinely risky behaviour without cataloguing every keystroke and website visit.
Behaviour baselines over content inspection
The most effective and least invasive approach focuses on behavioural patterns rather than content. Instead of reading emails or monitoring screen content, track metadata: access patterns, data volumes, login times, and system usage.
When a user who normally accesses 50 files per day suddenly accesses 5,000, that behavioural deviation is detectable without knowing what any of those files contain. The anomaly triggers investigation; the investigation determines intent.
Focus on high-risk indicators
Not all user activity needs the same level of monitoring. Concentrate on scenarios that represent genuine risk:
- Data exfiltration patterns: Large volumes of data moved to personal cloud storage, USB devices, or personal email.
- Access anomalies: Users accessing systems, data, or networks they do not normally use.
- Privilege abuse: Users with elevated access using it outside their normal work patterns.
- Resignation indicators: When HR confirms an employee is leaving, heightened monitoring of their data access is proportionate and often necessary.
Technical implementation
Use entity behaviour analytics (UEBA) to establish normal patterns for each user. Detect deviations automatically. This reduces the volume of data that humans need to review.
Aggregate and anonymise where possible. Dashboard views should show trends and anomalies, not individual user activity logs, until an investigation is warranted.
Implement tiered alerting. Low-confidence anomalies generate silent logs for retroactive investigation. High-confidence indicators, like bulk data download to personal storage, trigger immediate review.
Define clear policies. Employees should know that certain activities are monitored for security purposes. Transparency about what is monitored and why builds trust rather than eroding it.
Governance matters
An insider threat programme without governance is a surveillance programme. Establish clear policies covering:
- What data is collected and why
- Who can access monitoring data
- Under what circumstances individual-level investigation is authorised
- How long monitoring data is retained
- How the programme complies with applicable privacy regulations
Review the programme regularly with legal, HR, and privacy stakeholders. Document your proportionality assessments.
SenseOn's behavioural detection capabilities support insider threat programmes that are both effective and proportionate. Our approach focuses on anomaly detection across telemetry metadata rather than invasive content monitoring.
