Experimental Study of DIGIPASS GO3 and the Security of Authentication

TL;DR

This study analyzes DIGIPASS GO3's OTP system, revealing vulnerabilities that allow forgery attacks with a higher success probability than expected, posing significant security risks for organizations.

Contribution

It reconstructs the token's synchronization, algorithm, and protocol, demonstrating vulnerabilities and potential for large-scale account compromises.

Findings

OTP predictability is higher than expected

Forgery attack success probability is approximately 8^-5

Potential for over 100 compromised accounts annually in small organizations

Abstract

Based on the analysis of $6$-digit one-time passwords(OTP) generated by DIGIPASS GO3 we were able to reconstruct the synchronisation system of the token, the OTP generating algorithm and the verification protocol in details essential for an attack. The OTPs are more predictable than expected. A forgery attack is described. We argue the attack success probability is $8^{-5}$. That is much higher than $10^{-6}$ which may be expected if all the digits are independent and uniformly distributed. Under natural assumptions even in a relatively small bank or company with $10^4$ customers the number of compromised accounts during a year may be more than $100$.