Diversity and resistance in a model network with adaptive software

Abstract Attacks on computers are increasingly sophisticated, automated and damaging. We take inspiration from the diversity and adaptation of the immune system to design a new kind of computer security system utilizing automated repair techniques. We call the principles of effective immune system design Scalable RADAR: Robust Adaptive Decentralized Search and Automated Response. This paper explores how node diversity is maintained on a network that can generate software variants at individual nodes and make local decisions about sharing variants between nodes. We explore the effects of different network topologies on software diversity and resource trade-offs. We examine how the architecture of the lymphatic network balances trade-offs between local and global search for pathogens in order to improve our design. Experiments are performed on model networks of connected computers able to automatically generate repairs to their own software in response to an attack, bug, or vulnerability. We find that increased connectivity leads to increased overhead, but decreased time to repair, and that small world networks more efficiently distribute repairs. Diversity is diminished by increased connectivity, but has a more complex relationship with network structure, for example, a highly connected network may exhibit low overall diversity but maintain high diversity in a small number of low degree nodes in the periphery of the network.