Data exfiltration, data loss or data leakage is essentially the removal of information or data from an electronic device, typically a computer, mobile phone or other Internet connected device.

Data exfiltration can be divided into two categories, outsiders trying to infiltrate the network to steal valuable corporate data, and people on the inside willing to share it. Whilst often malicious in nature data exfiltration can also be the result of insider carelessness, sending confidential documents to personal email accounts and / or cloud servers.

Data exfiltration can be very difficult to detect. As data routinely moves in and out of an organization, data exfiltration can closely resemble normal network traffic, meaning that data loss incidents often go unnoticed by IT staff until the damage has been done.