Cryptology ePrint Archive: Report 2021/640

Security and Trust in Open Source Security Tokens

Marc Schink and Alexander Wagner and Florian Unterstein and Johann Heyszl

Abstract: Using passwords for authentication has been proven vulnerable in countless security incidents. Hardware authentication tokens effectively prevent most password-related security issues and improve security indisputably. However, we would like to highlight that there are new threats from attackers with physical access which need to be discussed. Supply chain adversaries may manipulate devices on a large scale and install backdoors before they even reach end users. In evil maid scenarios, specific devices may even be attacked while already in use. Hence, we thoroughly investigate the security and trustworthiness of eight commercially available open source authentication tokens, including devices from the two market leaders: SoloKeys and Nitrokey. Unfortunately, we identify and practically verify significant vulnerabilities in all eight examined tokens. Some of them based on severe, previously undiscovered, vulnerabilities of three major microcontroller products which are used at a large scale in various products. Our findings clearly emphasize the significant threat from supply chain and evil maid scenarios since the attacks are practical and only require moderate attacker efforts. Fortunately, we are able to describe software-based countermeasures as effective improvements to retrofit the examined devices. To improve the security and trustworthiness of future authentication tokens, we also derive important general design recommendations.

Category / Keywords: applications / security token, second factor authentication, FIDO, fault injection attack, side-channel attack, firmware protection

Original Publication (with minor differences): IACR-CHES-2021

Date: received 15 May 2021

Contact author: marc schink at aisec fraunhofer de

Available format(s): PDF | BibTeX Citation

Version: 20210517:063843 (All versions of this report)

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