  Evil twin attack on Wi-Fi network has been a challenging security problem and
several solutions have been proposed to this problem. In general, evil twin
attack aims to exfiltrate data, like Wi-Fi and service credentials, from the
client devices and considered as a serious threat at MAC layer. IoT devices
with its companion apps provides different pairing methods for provisioning.
The "SmartConfig Mode", the one proposed by Texas Instrument (TI) and the
"Access Point pairing mode (AP mode)" are the most common pairing modes
provided by the application developer and vendor of the IoT devices.
Especially, AP mode use Wi-Fi connectivity to setup IoT devices where a device
activates an access point to which the mobile device running the corresponding
mobile application is required to connect. In this paper, we have used evil
twin attack as a weapon to test the security posture of IoT devices that use
Wi-Fi network to set them up. We have designed, implemented and applied a
system, called iTieProbe, that can be used in ethical hacking for discovering
certain vulnerabilities during such setup. AP mode successfully completes when
the mobile device is able to communicate with the IoT device via a home router
over a Wi-Fi network. Our proposed system, iTieProbe, is capable of discovering
several serious vulnerabilities in the commercial IoT devices that use AP mode
or similar approach. We evaluated iTieProbe's efficacy on 9 IoT devices, like
IoT cameras, smart plugs, Echo Dot and smart bulbs, and discovered that several
of these IoT devices have certain serious threats, like leaking Wi-Fi
credential of home router and creating fake IoT device, during the setup of the
IoT devices.
