On the Detection of Hidden Terrorist Cells Immersed in Peer-to-peer Networks

Hidden terrorist cells in high dimensional communications networks arise when terrorists camouflage connectivity to appear randomly connected to the background network. We investigate hidden network detectability when the background network does not support terrorist activities. Using two September 11 terrorist networks as the test bed and a network measure called assortativity, we suggest hidden terrorist networks can behave as Peer-to-Peer networks. We compare the September 11 hidden networks with Peer-toPeer networks containing embedded terrorist networks, as well as with generic Peer-to-Peer networks. Using Peer-to-Peer characteristics and social network group-based centralities, we show that for certain Peer-to-Peer networks it is possible to detect hidden terrorist networks in cyberspace, with potential future application to Instant Messaging and Skype networks.