On the Potential of IPv6 Open Resolvers for DDoS Attacks

Distributed Denial of Service (DDoS) attacks have become a daily problem in today’s Internet. These attacks aim at overwhelming online services or network infrastrucure. Some DDoS attacks explore open services to perform reflected and amplified attacks; and the DNS is one of the most (mis)used systems by attackers. This problem can be further aggravated in the near future by the increasing number of IPv6-enabled services in the Internet. Given that the deployment of IPv6-enabled services is increasing, it becomes important to find vulnerable IPv6 open services that could be (mis)used by attackers, and prevent that misuse. However, unlike with IPv4, simply scanning the IPv6 address space to find these open services is impractical. In this paper we present an active measurement approach to enumerate a relevant list of open resolvers on IPv6 in the wild that could be potentially exploited in a DDoS attack. Based on the assumption that IPv6 open resolvers can be found via IPv4 ones, we show that IPv6-based amplified DDoS attacks are a significantly potential threat in the Internet: the analyzed resolvers, of which 72% are assumingly infrastructural servers, showed a median amplification factor of 50.