The Postman: A Journey of Ethical Hacking in PosteID/SPID Borderland

This paper presents a vulnerability assessment activity that we carried out on PosteID, the implementation of the Italian Public Digital Identity System (SPID) by Poste Italiane. The activity led to the discovery of a critical privilege escalation vulnerability, which was eventually patched. The overall analysis and disclosure process represents a valuable case study for the community of ethical hackers. In this work, we present both the technical steps and the details of the disclosure process.