Leech is a multi-media composition that explores the moral and physical dimensions of music piracy. Leech includes components of sonification and music composition, using the actual mechanisms that enable BitTorrent downloads as mined data for real-time algorithmic sound production. Network data is mapped in musically and visually meaningful ways to produce an experience that embodies the look and sound of piracy. Furthermore, the actual music being pirated is itself used as a resource for audio processing and music composition. Performed in real-time, the composition provides multi-factorial insight into the world of music piracy.