What does exfiltrated mean?
"Exfiltrated" is the past tense and past participle of "exfiltrate," a verb meaning to remove someone or something secretly and stealthily from a place or system. The word originated in military and intelligence circles, where it described covert operations to extract agents, prisoners, or downed pilots from hostile territory — the logical counterpart of "infiltrate," which means to enter secretly rather than exit. In recent decades its center of gravity has shifted to cybersecurity: when hackers breach a network and copy out sensitive files without authorization, those files are said to have been exfiltrated. The term carries connotations of secrecy, skill, and illegality, and it appears almost exclusively in technical, journalistic, or formal registers. Its precision makes it valuable: unlike the vaguer "stolen" or "leaked," "exfiltrated" implies a deliberate, covert extraction across a boundary — whether a border, a perimeter, or a firewall — and signals insider familiarity with security language.
verb (past tense and past participle of 'exfiltrate')Having been withdrawn or removed secretly and stealthily, especially data or information extracted illicitly from a computer system, or personnel spirited out of a dangerous area. It carries a strong association with covert military operations and cybersecurity breaches.
- (of data or information) Removed or copied illicitly and covertly from a computer system or secure network.
- (of people) Withdrawn secretly from a hostile or dangerous area, typically by special forces or intelligence operatives.
"Investigators discovered that millions of customer records had been exfiltrated from the company's servers over several months."
"The malware quietly exfiltrated credentials whenever the user logged into their bank account."
"A captured pilot was exfiltrated from enemy territory under cover of darkness."
Hackers don't just steal your data — in security jargon, they 'exfiltrate' it, borrowing a word that spies once used for smuggling people across borders.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of exfiltrated
"Exfiltrate" was formed from the Latin-derived prefix "ex-" (out of) combined with "filtrate," from Medieval Latin "filtrare" (to filter), ultimately rooted in "filtrum," meaning felt used as a strainer. The word arose as a deliberate reverse of "infiltrate," which entered English in the mid-19th century, with "exfiltrate" emerging in 20th-century military vocabulary. Its cognates include "filter," "filtration," and "infiltrate," all descending from the same filtering metaphor — passing material through a barrier.
Related word forms
How exfiltrated is actually used
Originally a military and intelligence term for extracting personnel covertly, 'exfiltrated' has become dominant in cybersecurity contexts, where it describes unauthorized outbound transfer of data. The tone is technical and formal; it rarely appears in casual conversation. Insecurity reporting it often appears in passive constructions such as 'data was exfiltrated'.
Easily confused with exfiltrated
To infiltrate is to enter or penetrate secretly, while to exfiltrate is to exit or remove something secretly — the two are directional opposites.