In the context of connecting to enterprise Wi-Fi, previous works show that relying on human users to manually configure or enforce server authentication often leads to insecure outcomes. Consequently, many user credentials can potentially be stolen by the so-called "Evil-Twin'' (ET) attack. To ease the burden of human users, various easy-to-use Wi-Fi configurators have been released and deployed. In this work, we investigate whether such configurators can indeed protect users from variants of the ET attack. To our surprise, the results of our investigation show that all configurators considered in the study suffer from certain weaknesses due to their design, implementation, or deployment practices. Notable findings include a series of design flaws in the new trust-on-first-use (TOFU) configurator on Android (available since version 12), which can be exploited in tandem to achieve a stealthy ET attack. Moreover, we found that 2 open-source Android Wi-Fi configurators fail to properly enforce server authentication under specific situations. The cause of these could be partly attributed to the complexity stemmed from certificate name matching as well as the limitations of the Android API. Last but not least, we found that a commercial configurator not only allows insecure Wi-Fi configurations to be deployed, but also the covert injection of certificates on the user device to facilitate interception of other TLS traffic, posing yet another hidden security and privacy threat to its users. All in all, this study shows that despite years of research on the topic, developing a user-friendly yet reliable Wi-Fi configurator remains an elusive goal, and thus the threat of ET attacks continues to be relevant. As such, it is time to rethink whether the complexity of the standard certificate chain validation is actually good for enterprise Wi-Fi.

In this paper, we perform the first multifaceted measurement study to investigate the widespread insecure practices employed by tertiary education institutes (TEIs) around the globe when offering WPA2-Enterprise Wi-Fi services. The security of such services critically hinges on two aspects: (1) the connection configuration on the client-side; and (2) the TLS setup on the authentication servers. Weaknesses in either can leave users susceptible to credential theft. Typically, TEIs prescribe to their users either manual instructions or pre-configured profiles (e.g., eduroam CAT). For studying the security of configurations, we present a framework in which each configuration is mapped to an abstract security label drawn from a strict partially ordered set. We first used this framework to evaluate the configurations supported by the user interfaces (UIs) of mainstream operating systems (OSs), and discovered many design weaknesses. We then considered 7045 TEIs in 54 countries/regions, and collected 7275 configuration instructions from 2061 TEIs. Our analysis showed that majority of these instructions lead to insecure configurations, and nearly 86% of those TEIs can suffer from credential thefts on at least one OS. We also analyzed a large corpus of pre-configured eduroam CAT profiles and discovered several misconfiguration issues that can negatively impact security. Finally, we evaluated the TLS parameters used by authentication servers of thousands of TEIs and discovered perilous practices, such as the use of expired certificates, deprecated versions of TLS, weak signature algorithms, and suspected cases of private key reuse among TEIs. Our long list of findings have been responsibly disclosed to the relevant stakeholders, many of which have already been positively acknowledged.

This paper focuses on developing an automatic, black-box testing approach called Morpheus to check the non-compliance of libraries implementing PKCS#1-v1.5 signature verification with the PKCS#1-v1.5 standard. Non-compliance can not only make implementations vulnerable to Bleichenbacher-style RSA signature forgery attacks but also can induce interoperability issues. For checking non-compliance, Morpheus adaptively generates interesting test cases and then takes advantage of an oracle, a formally proven correct implementation of PKCS#1-v1.5 signature standard, to detect non-compliance in an implementation under test. We have used Morpheus to test 45 implementations of PKCS#1-v1.5 signature verification and discovered that 6 of them are susceptible to variants of the Bleichenbacher-style low public exponent RSA signature forgery attack, 1 implementation has a buffer overflow, 33 implementations have incompatibility issues, and 8 implementations have minor leniencies. Our findings have been responsibly disclosed and positively acknowledged by the developers.