Insider Threats: When the Risk Is Already Inside the Building

The 30-second explanation

The person already has the keys. They might be careless, tricked, or upset. Either way, normal security that stops outsiders does not stop them.

How it works

1. 1

   1. Legitimate access

   The person is trusted and allowed in.

2. 2

   2. Trigger

   A mistake, pressure, grievance or compromise.

3. 3

   3. Action

   Data is exposed, copied or misused.

4. 4

   4. Detection

   Behaviour differs from the person's normal pattern.

Most insider incidents are accidents: a file shared with the wrong person, a laptop lost, a link clicked. A smaller number are deliberate, often around a departure or a grievance. Because the access is legitimate, the useful signals are changes in behaviour: unusual volumes, unusual hours, access to data outside someone's role. The best programmes combine good access hygiene, fair processes and monitoring that is transparent and proportionate.

Real-world example

How to spot it

• Unusual data volume

  Large downloads or copies outside a person's normal pattern.

• Access outside the role

  Browsing systems or files that have nothing to do with the job.

• Odd hours

  Repeated out-of-hours access without a reason.

• Use of personal storage

  Sending work data to personal accounts.

What to do

1. 1Give people the minimum access they need, and remove it promptly when roles change or people leave.
2. 2Monitor sensitive data movement in a way staff know about, and treat alerts fairly and privately.
3. 3Make it easy to report mistakes quickly, without blame, so small errors do not become breaches.