Information leakage is a growing public concern. This paper describes a visualization system for tracing leaks involving confidential information. In particular, the system enables administrators to determine which hosts have confidential documents and the means by which confidential information is transmitted, received and duplicated. The visualization system is scalable to large organizations and can track various means of information propagation in a seamless manner. Also, it helps prevent information leaks, analyze transmission routes and present forensic evidence.