exfiltrate

Exfiltrate is a verb meaning to withdraw something—commonly data, people, or goods—from a location, often covertly or illegally. The term is used across several fields, including information security, military operations, and journalism. The corresponding noun, exfiltration, refers to the act or process of such withdrawal.

Originating from Latin exfiltrare (out + filtrāre, to filter), the term entered English with the sense of escaping or withdrawing. In modern usage, exfiltration often implies an unauthorized or hidden exit.

In information security, data exfiltration denotes the unauthorized transfer of data from a target system to an external destination. It is a key concern in breach investigations and incident response, and defenders aim to prevent it through access controls, data loss prevention, encryption, monitoring, and network segmentation. Exfiltration can occur through various channels, including email, removable media, or covert network channels, but detailed techniques are outside its general description to avoid facilitating wrongdoing.

In military and intelligence contexts, exfiltration refers to the withdrawal of personnel, equipment, or agents from hostile or compromised areas. Such operations emphasize secure extraction routes, timing, and safety measures, and may be planned as part of a broader mission or evacuation.

Because exfiltration often involves evading security or legal controls, it is frequently illegal or illicit when conducted without authorization. Legitimate uses include authorized data migration, disaster recovery, or rescue operations where permission has been granted or lawfully mandated. Organizations seek to detect and deter exfiltration through governance, auditing, and security monitoring.