6Sense: Internet-Wide IPv6 Scanning and its Security Applications

Internet-wide scanning is a critical tool for security researchers and practitioners alike. By exhaustively exploring the entire IPv4 address space, Internet scanning has driven the development of new security protocols, found and tracked vulnerabilities, improved DDoS defenses, and illuminated global censorship. Unfortunately, the vast scale of the IPv6 address space-340 trillion trillion trillion addresses-precludes exhaustive scanning, necessitating entirely new IPv6-specific scanning methods. As IPv6 adoption continues to grow, developing IPv6 scanning methods is vital for maintaining our capability to comprehensively investigate Internet security. We present 6SENSE, an end-to-end Internet-wide IPv6 scanning system. 6SENSE utilizes reinforcement learning coupled with an online scanner to iteratively reduce the space of possible IPv6 addresses into a tractable scannable subspace, thus discovering new IPv6 Internet hosts. 6SENSE is driven by a set of metrics we identify and define as key for evaluating the generality, diversity, and correctness of IPv6 scanning. We evaluate 6SENSE and prior generative IPv6 discovery methods across these metrics, showing that 6SENSE is able to identify tens of millions of IPv6 hosts, which compared to prior approaches, is up to 3.6x more hosts and 4x more end-site assignments, across a more diverse set of networks. From our analysis, we identify limitations in prior generative approaches that preclude their use for Internet-scale security scans. We also conduct the first Internet-wide scanning-driven security analysis of IPv6 hosts, focusing on TLS certificates unique to IPv6, surveying open ports and security-sensitive services, and identifying potential CVEs.