Devices, systems, and methods of detecting whether an electronic device or computerized device or computer, is being controlled by a legitimate human user, or by an automated cyber-attack unit or malware or automatic script. The system monitors interactions performed via one or more input units of the electronic device. The system searches for abnormal input-user interactions; or for an abnormal discrepancy between: the input-unit gestures that were actually registered by the input unit, and the content that the electronic device reports as allegedly entered via such input units. A discrepancy or abnormality indicates that more-possibly a malware or automated script is controlling the electronic device, rather than a legitimate human user. Optionally, an input-output aberration or interference is injected, in order to check for manual corrective actions that only a human user, and not an automated script, is able to perform.