Proactive obfuscation

Proactive obfuscation is a new method for creating server replicas that are likely to have fewer shared vulnerabilities. It uses semantics-preserving code transformations to generate diverse executables, periodically restarting servers with these fresh versions. The periodic restarts help bound the number of compromised replicas that a service ever concurrently runs, and therefore proactive obfuscation makes an adversary's job harder. Proactive obfuscation was used in implementing two prototypes: a distributed firewall based on state-machine replication and a distributed storage service based on quorum systems. Costs intrinsic to supporting proactive obfuscation in replicated systems were evaluated by measuring the performance of these prototypes. The results show that employing proactive obfuscation adds little to the cost of replica-management protocols.