Discovering Logical Vulnerabilities in the Wi-Fi Handshake Using Model-Based Testing

Abstract

We use model-based testing techniques to detect logical vulnerabilities in implementations of the Wi-Fi handshake. This reveals new fingerprinting techniques, multiple downgrade attacks, and Denial of Service (DoS) vulnerabilities. Stations use the Wi-Fi handshake to securely connect with wireless networks. In this handshake, mutually supported capabilities are determined, and fresh pairwise keys are negotiated. As a result, a proper implementation of the Wi-Fi handshake is essential in protecting all subsequent traffic. To detect the presence of erroneous behaviour, we propose a model-based technique that generates a set of representative test cases. These tests cover all states of the Wi-Fi handshake, and explore various edge cases in each state. We then treat the implementation under test as a black box, and execute all generated tests. Determining whether a failed test introduces a security weakness is done manually. We tested 12 implementations using this approach, and discovered irregularities in all of them. Our findings include fingerprinting mechanisms, DoS attacks, and downgrade attacks where an adversary can force usage of the insecure WPA-TKIP cipher. Finally, we explain how one of our downgrade attacks highlights incorrect claims made in the 802.11 standard.

Practical Side-Channel Attacks against WPA-TKIP

“…The usage of TKIP is being discouraged by the Wi-Fi Alliance [7], however, WPA2 certified devices are still allowed to support both TKIP and CCMP. Several vulnerabilities have been found in WPA2 implementations [28,35], and more recently we have seen key reinstallation attacks (KRACKs) against the WPA2 standard itself [33,34].…”

“…It has been shown that MediaTek devices may be vulnerable to a downgrade attack from AES-CCMP to WPA-TKIP [35]. As a result, clients using AES-CCMP may be downgraded to WPA-TKIP and fall victim to our attack.…”

“…In addition, researchers identified vulnerabilities in technology surrounding Wi-Fi, such as Wi-Fi Protected Setup (WPS) [26,36]. In [12], message forging attacks against AES-CCMP were described, and several WPA2 implementations have been analyzed in works such as [28,35] revealing how clients may be downgraded from AES-CCMP to WPA-TKIP. Downgrading clients to WPA-TKIP makes them vulnerable to the attacks devised against it.…”

A framework to test and fuzz wi-fi devices

“…ACM ISBN 978-1-4503-8349-3/21/06. https://doi.org/10.1145/3448300.3468261 modeled the four-way handshake to identify weaknesses [7,11], inspected the impact of Wi-Fi Protected Setup (WPS) flaws [4], and proposed numerous methods to enhance the security of Wi-Fi networks, for example, by presenting an extensive formal analysis of the WPA2 protocol design [2]. In their experiments, researchers are often required to implement complex features or entire procedures from scratch (e.g., using Python and Scapy).…”

Solving Downgrade and DoS Attack Due to the Four Ways Handshake Vulnerabilities (WIFI)

“…The nature of wireless network transmission and the emerging attacks are continuously creating or exploiting more vulnerability [3]. Despite the fact that the security mechanism and protocols are upgraded and enhanced, some companies or organization environments cannot afford a separate authentication system, and generally adopt the Wi-Fi-Protected-Access/Preshared-key(WPA2-PSK) which is not assuring 100 % security and are still exposed to some categories of attacks such as downgrade attacks, de-authentication attacks and DoS, that aims to push wireless clients to re-authenticate to Access point( AP) and try to capture the key exchanged during the handshake to compromise the network security [4].…”