Robustness of keystroke-dynamics based biometrics against synthetic forgeries

摘要

Biometric systems including keystroke-dynamics based authentication have been well studied in the literature. The attack model in biometrics typically considers impersonation attempts launched by human imposters. However, this attack model is not adequate, as advanced attackers may utilize programs to forge data. In this paper, we consider the effects of synthetic forgery attacks in the context of biometric authentication systems. Our study is performed in a concrete keystroke-dynamic authentication system. The main focus of our work is evaluating the security of keystroke-dynamics authentication against synthetic forgery attacks. Our analysis is performed in a remote authentication framework called TUBA that we design and implement for monitoring a user's typing patterns. We evaluate the robustness of TUBA through experimental evaluation including two series of simulated bots. The keystroke sequences forged by the two bots are modeled using first-order Markov chains. Support vector machine is used for classification. Our results, based on 20 users' keystroke data, are reported. Our work shows that keystroke dynamics is robust against the two specific types of synthetic forgery attacks studied, where attacker draws statistical samples from a pool of available keystroke dataset other than the target. We also describe TUBA's use for detecting anomalous activities on remote hosts, and present its use in a specific cognition-based anomaly detection system. The use of TUBA provides high assurance on the information collected from the hosts and enables remote security diagnosis and monitoring.