Abstract—Biometrics-based authentication systems are presented
as an alternative solution to the traditional authentication
techniques, these systems have more security advantages compared
to a password as biometric data cannot be forgotten or
wasted. However, the protection of biometric systems against
different types of attacks is not yet guaranteed. While many
studies are proposed in order to increase the security of biometric
systems, several attacks are developed in order to exploit the
weaknesses of these systems. In this paper, we present a new
alteration attack on biometric authentication systems. We suppose
that the impostor has altered image of the real user and he
presents it as request in order to gain unlawful access to the
system. Altered image can be recuperated from a fingerprint
trace in case of fingerprint based systems or user photograph for
attacking face based authentication systems. Next, we study the
impact of alteration level on the matching score for fingerprint
and face based biometric systems. Our analysis shows that both
systems are vulnerable to the proposed attack and the alteration
level has serious impact on the security of biometric systems.
The impostor can have a matching score greater than 90%
for the tested fingerprint based biometric system and 190/194
associations are matched for the tested face based biometric
authentication system.