Understanding how insider threats occur, the warning signs to watch for, and how to protect your organisation.
Insider Threats
An insider threat is a security risk that originates from within the organisation — from current or former employees, contractors, or business partners who have authorised access to systems and data.
Types of Insider Threats
Insider threats fall into a few broad categories: malicious insiders who intentionally steal or sabotage; negligent insiders who accidentally expose data through carelessness (the most common type, and the most fixable with training); compromised accounts where an external attacker controls a legitimate employee login; and departing employees who copy data on their way out — exfiltration that spikes in the final two weeks.
Why Insider Threats Are Hard to Detect
- Insiders already have legitimate access — there is no “break-in” to detect
- Malicious activity often mimics normal work behaviour
- Employees are trusted — unusual actions may not be questioned
- Detection requires behavioural analytics that many smaller organisations lack
Warning Signs
| Behavioural | Technical |
|---|---|
| Unexplained interest in data outside their role | Mass file downloads or USB copies |
| Downloading large data shortly before resignation | Emailing large attachments to personal email |
| Accessing systems at unusual hours | Use of unauthorised cloud storage (Dropbox) |
| Expressing grievances about the organisation | Access to systems unrelated to current role |
| Circumventing security controls “for convenience” | Accounts logging in from multiple locations simultaneously |
⚠ Warning
Data exfiltration spikes significantly in the two weeks before a resignation. Organisations should monitor for unusual data movements when employees give notice — not as a punitive measure, but as a standard security control. If you notice a colleague copying large volumes of files before leaving, report it to your manager or security team.
Protective Controls
- Principle of least privilege — access only to what the role requires
- Separation of duties — no single person controls an entire sensitive process
- Offboarding procedures — access revoked on the employee’s last day
- Data Loss Prevention (DLP) tools — detect and block large data transfers
- Audit logging — who accessed what, and when
- Positive culture — employees who feel valued are less likely to act maliciously
✓ Key Point
If you observe suspicious behaviour from a colleague — large file copies, unusual access patterns, or stated intent to take company data — report it through the correct channel (manager, HR, or security team). Do not confront the person directly. Insider threat investigations require proper handling to protect evidence and legal process.
