  The evil twin attack is a major security threat to WLANs. An evil twin is a
rogue AP installed by a malicious user to impersonate legitimate APs. It
intends to attract victims in order to intercept their credentials, to steal
their sensitive information, to eavesdrop on their data, etc. In this paper, we
study the security mechanisms of wireless networks and we introduce the
different authentication methods, including 802.1X authentication. We show that
802.1X has improved security through the use of digital certificates but does
not define any practical technique for the user to check the network
certificate. Therefore, it remains vulnerable to the evil twin attack. To
repair this vulnerability, we introduce Robust Certificate Management System
(RCMS) which takes advantage of the digital certificates of 802.1X to protect
the users against rogue APs. RCMS defines a new verification code to allow the
user device to check the network certificate. This practical verification
combined with the reliability of digital certificates provides a perfect
protection against rogue APs. RCMS requires a small software update on the user
terminal and does not need any modification of IEEE 802.11. It has a
significant flexibility since trusting a single AP is enough to trust all the
APs of the extended network. This allows the administrators to extend their
networks easily without the need to update any database of trusted APs on the
user devices.
