Insider threat

Insiders are not only employees but also contractors, students, suppliers and partners with access, and former employees whose access was not revoked in time. Practice distinguishes three case types: malicious (theft of data or intellectual property, fraud, sabotage, passing information to third parties), negligent (mistakes, bypassed procedures, unsanctioned tools, lost devices) and compromised, where an external attacker takes over an employee's identity.

These cases are difficult because the access is legitimate: no perimeter is breached, the person knows the internal controls and their weak points, and the damage is often discovered late. Motives vary — financial pressure, a sense of injustice after a personnel decision, ideology, ego, or external recruitment. Behavioral and organizational indicators can be a useful warning but are never proof in themselves and must be handled with restraint and documented.

Controls are largely organizational: least privilege, segregation of incompatible duties, four-eyes approval for high-risk transactions, a disciplined joiner-mover-leaver process, periodic review of granted access, logging of privileged actions, monitoring for data exfiltration, a secure and confidential reporting channel, and pre-employment screening within the limits the law allows.

Monitoring employees is processing of personal data and an intrusion into reasonable expectations of privacy, so it requires a legal basis, must be proportionate, defined in advance in an internal policy and transparent; blanket covert monitoring is generally not permissible. Suspected cases are investigated so that evidence is preserved under chain-of-custody rules, since internal matters frequently continue as a criminal complaint, a labor dispute or a damages claim.