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We analyze the Secure Remote Password (SRP) protocol for structural weaknesses using the Cryptographic Protocol Shapes Analyzer (CPSA) in the first formal analysis of SRP (specifically, Version 3). SRP is a widely deployed Password Authenticated Key Exchange (PAKE) protocol used in 1Password, iCloud Keychain, and other products. As with many PAKE protocols, two participants use knowledge of a preshared password to authenticate each other and establish a session key. SRP aims to resist dictionary attacks, not store plaintext-equivalent passwords on the server, avoid patent infringement, and avoid export controls by not using encryption. Formal analysis of SRP is challenging in part because existing tools provide no simple way to reason about its use of the mathematical expression “v + g b mod q”. Modeling v + g b as encryption, we complete an exhaustive study of all possible execution sequences of SRP. Ignoring possible algebraic attacks, this analysis detects no major structural weakness, and in particular no leakage of any secrets. We do uncover one notable weakness of SRP, which follows from its design constraints. It is possible for a malicious server to fake an authentication session with a client, without the client’s participation. This action might facilitate an escalation of privilege attack, if the client has higher privileges than does the server. We conceived of this attack before we used CPSA and confirmed it by generating corresponding execution shapes using CPSA. 

For the third consecutive year, Scholarship for Service (SFS) scholars at the University of Maryland, Baltimore County (UMBC) analyzed the security of targeted portions of the UMBC computer systems. During these hands-on studies, with complete access to sourcecode, students identified vulnerabilities, devised and implemented exploits, and recommended mitigations. We report on our continuing experiences with these project-based learning studies, focusing on the new problems addressed in January 2018 and 2019 and on the lessons we learned. In 2018, students analyzed the WebAdmin custom software that UMBC students, faculty, and staff use to manage credentials and accounts. Students found a beautifully instructive example of a “confused-deputy attack,” wherein an IT staff member—–through carrying out their proper procedures for resetting a user password—–unwittingly executes malware on their own machine by viewing the answers to security questions. In 2019, students analyzed the Virthost system UMBC uses to host student webpages. Organizer Alan Sherman created a powerful learning experience by secretly recruiting one of the participants to serve as a “mole,” passively collecting passwords from the other participants throughout the week. Our students found the collaborative experiences inspirational; students and educators appreciated the authentic case studies; and IT administrators gained access to future employees and received free recommendations for improving the security of their systems.