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Vol. 1 · Ed. 2026
CyberGlossary
Entry № 542

Insider Threat

What is Insider Threat?

Insider ThreatThe risk that a current or former employee, contractor, or partner with authorised access misuses it to cause harm, intentionally or by negligence.


Insider threats fall into three patterns. Malicious insiders deliberately exfiltrate data, sabotage systems, commit fraud, or sell access; common motives include money, revenge, ideology, or coercion. Negligent insiders cause incidents through poor security hygiene (mishandled documents, weak passwords, mis-sent emails, shadow IT). Compromised insiders are legitimate users whose accounts have been taken over by external attackers. Detection programs combine HR signals, UEBA, DLP, privileged-access monitoring, separation of duties, and need-to-know policies. Notable cases include the 2013 Edward Snowden NSA disclosures, the 2010 Chelsea Manning leaks to WikiLeaks, and many ransomware-deployment cases where employees are recruited or extorted by external gangs.

Examples

  1. 01

    A departing engineer copies source code and customer lists to a personal cloud drive before resigning.

  2. 02

    A help-desk employee is socially engineered by a ransomware crew to reset MFA on a privileged account.

Frequently asked questions

What is Insider Threat?

The risk that a current or former employee, contractor, or partner with authorised access misuses it to cause harm, intentionally or by negligence. It belongs to the Defense & Operations category of cybersecurity.

What does Insider Threat mean?

The risk that a current or former employee, contractor, or partner with authorised access misuses it to cause harm, intentionally or by negligence.

How does Insider Threat work?

Insider threats fall into three patterns. Malicious insiders deliberately exfiltrate data, sabotage systems, commit fraud, or sell access; common motives include money, revenge, ideology, or coercion. Negligent insiders cause incidents through poor security hygiene (mishandled documents, weak passwords, mis-sent emails, shadow IT). Compromised insiders are legitimate users whose accounts have been taken over by external attackers. Detection programs combine HR signals, UEBA, DLP, privileged-access monitoring, separation of duties, and need-to-know policies. Notable cases include the 2013 Edward Snowden NSA disclosures, the 2010 Chelsea Manning leaks to WikiLeaks, and many ransomware-deployment cases where employees are recruited or extorted by external gangs.

How do you defend against Insider Threat?

Defences for Insider Threat typically combine technical controls and operational practices, as detailed in the full definition above.

What are other names for Insider Threat?

Common alternative names include: Insider risk, Trusted insider threat.

Related terms

See also