A Formal Analysis of 5G Authentication

TL;DR

This paper provides a formal security analysis of the 5G AKA authentication protocol, revealing missing security guarantees and proposing fixes to enhance its robustness using automated verification tools.

Contribution

It offers the first formal model of 5G AKA, systematically evaluates its security, and suggests provably secure improvements based on automated analysis.

Findings

Some security goals are not met without additional assumptions

Identified critical security weaknesses in the 5G AKA protocol

Proposed secure fixes to address identified vulnerabilities

Abstract

Mobile communication networks connect much of the world's population. The security of users' calls, SMSs, and mobile data depends on the guarantees provided by the Authenticated Key Exchange protocols used. For the next-generation network (5G), the 3GPP group has standardized the 5G AKA protocol for this purpose. We provide the first comprehensive formal model of a protocol from the AKA family: 5G AKA. We also extract precise requirements from the 3GPP standards defining 5G and we identify missing security goals. Using the security protocol verification tool Tamarin, we conduct a full, systematic, security evaluation of the model with respect to the 5G security goals. Our automated analysis identifies the minimal security assumptions required for each security goal and we find that some critical security goals are not met, except under additional assumptions missing from the standard. Finally, we make explicit recommendations with provably secure fixes for the attacks and weaknesses we found.