An insider threat is a risk that comes from someone with legitimate access to an organisation’s systems and data. Because the access is already granted, the person does not need to break anything. The question is whether what they do is normal.

What types of insider threat are there?

• Malicious insiders misuse access on purpose, for gain, revenge or ideology.
• Negligent insiders cause harm by mistake or carelessness, for example by sharing credentials or sending data to the wrong place.
• Compromised insiders are people whose accounts an external attacker has taken over.

Who counts as an insider?

Employees, contractors, suppliers, partners and anyone with an account. Administrators and other privileged users carry the most risk, because their access reaches the furthest.

What damage can an insider cause?

Theft or leakage of data, fraud, sabotage of systems, disruption of services and regulatory consequences. The impact depends on the access the person holds, which is why it is closely tied to the blast radius of their identity.

Why are insider threats hard to detect?

Everything an insider does is done with valid credentials, from a trusted device, using permissions granted to them. Nothing is broken and nothing is malicious in itself. Only the pattern, in context, reveals that something is wrong.

What are the warning signs?

• Activity outside the usual hours or pattern.
• Bulk queries or exports that are new for that identity.
• Access to systems unrelated to the person’s role.
• Unexpected privilege or group changes.
• Use of dormant or rarely used accounts.
• Attempts to work around controls.

No single sign proves misuse. The combination matters.

Why do access controls not stop insiders?

Access controls decide what a person is allowed to do. An insider acts within that permission. A rule cannot tell a legitimate administrator from someone abusing the same rights, which needs visibility into behaviour.

What does an insider threat look like in practice?

A sales manager who has resigned starts exporting customer lists from the CRM at night. Their permissions allow it, so nothing is blocked. Only the change in volume and timing, compared with their normal use, stands out.

How is an insider different from an external attacker?

An external attacker has to obtain access first. An insider already has it. A compromised insider blurs the line, because an outsider is using an insider’s account.

Why does offboarding matter?

People who leave or change role often keep access longer than they should, and dormant accounts that still work are easy to misuse. Prompt, complete removal of access is one of the simplest ways to reduce insider risk.

How do privacy and trust fit in?

Monitoring colleagues involves personal data, so it must be proportionate, transparent and designed with data protection in mind, with legal, HR and privacy teams involved from the start and, where applicable, employee representatives.

How does behavioural monitoring help?

It learns what is normal for each identity, in its role, and flags meaningful deviations such as an unusual query, a new system or a change in volume. Risk-based prioritisation then puts the most serious cases first, so analysts do not need to read every log.

How do you respond in proportion?

Not every deviation deserves the same reaction. Options range from asking for additional authentication to restricting privileges for the session, ending it or escalating to an analyst. High-impact decisions should stay with people, and every step should be recorded.

How do you reduce insider risk?

Apply least privilege, remove access promptly when people move or leave, separate duties for sensitive actions and monitor behaviour. Agree the policy with legal, HR and privacy teams first, because monitoring colleagues must be proportionate and transparent.

Sharelock monitors behaviour after login, down to individual transactions and queries on critical applications, so misuse by someone with legitimate access stands out against their normal pattern.

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