Adaptive Deterrence of DNS Cache Poisoning.

Many long-lived network protocols were not designed with adversarial environments in mind; security is often an afterthought. Developing security mechanisms for protecting such systems is often very challenging as they are required to maintain compatibility with existing implementations, minimize deployment cost and performance overhead. The Domain Name System (DNS) is one such noteworthy example; the lack of source authentication has made DNS susceptible to cache poisoning. Existing countermeasures often suffer from at least one of the following limitations: insufficient protection; modest deployment; complex configuration; dependent on domain owners' participation. We propose CGuard which is an adaptive defense framework for caching DNS resolvers: CGuard actively tries to detect cache poisoning attempts and protect the cache entries under attack by only updating them through available high confidence channels. CGuard's effective defense is immediately deployable by the caching resolvers without having to rely on domain owners' assistance and is compatible with existing and future solutions. We have empirically demonstrated the efficacy of CGuard. We envision that by taking away the attacker's incentive to launch DNS cache poisoning attacks, CGuard essentially turns the existence of high confidence channels into a deterrence. Deterrence-based defense mechanisms can be applicable to other systems beyond DNS.