A Study on the Vulnerabilities of Openid Connect Based Federated Authentication System for Registration Data Access Protocol

Registration Data Access Protocol (RDAP) is designed to replace the classic WHOIS protocol by providing Representational State Transfer (RESTful) web services and tiered access control, enabling more secure and controlled data access based on the client's authorization level. Despite these improvements, the de-centralized management of registration metadata by various internet registries and registrars presents a challenge for users needing to obtain login credentials from multiple RDAP servers. This study examines the federated authentication mechanism proposed by RFC 9560 [8], identifying vulnerabilities within the current WHOIS/RDAP architecture and proposing countermeasures to enhance security and efficiency in the domain registration ecosystem.