What best defines data exfiltration?

• A. Data encryption at rest
• B. Unauthorized data transfer out of a network
• C. Internal data backups
• D. Data anonymization

Answer: (B)

Data exfiltration is the unauthorized transfer of data from within a network to an outside destination. The option that best defines this is the one describing an unauthorized data transfer out of a network, because exfiltration specifically means moving sensitive information beyond the organization without permission. Encryption at rest protects data while it’s stored, not the act of moving it out. Internal backups are legitimate copies kept for recovery, not illicit data removal. Data anonymization changes data to remove identifiers, which doesn’t by itself involve transferring data out of the network. In practice, look for unusual outbound data flows or transfers to external destinations to identify potential exfiltration, and apply controls like monitoring, data loss prevention, and restricted egress.