Data Exfiltration and Covert Channels

Within an organization, the possibility of a confidential information leak ranks among the highest fears of any executive. Detecting information leaks is a challenging problem, since most organizations depend on a broad and diverse communications network. It is not always straightforward to conclude which information is leaving the organization legitimately, and which communications are malicious data exfiltrations. Sometimes it is not even possible to tell that a communication is occurring at all. The set of all possible exfiltration methods contains, at a minimum, the set of all possible information communication methods, and possibly more. This article cannot possibly cover all such methods; however, several notable examples are given, and a taxonomy of data exfiltration is developed. Such a taxonomy cannot ever be exhaustive, but at the very least can offer a framework for organizing methods and developing defenses.