Ex filtrate is a verb that means to remove something from a particular place or organization without permission. Some of the antonyms for exfiltrate are invade, infiltrate, occupy, or seize. These verbs describe the opposite of exfiltration, as they involve entering a place or organization by force or without authorization. Other antonyms for exfiltrate include enter, stay, remain, or dwell. These words describe actions that involve staying in a place rather than leaving, which is contradictory to exfiltration. In summary, exfiltrate is a word that implies removal, so the antonyms are words that involve entering or staying in a place.