A Practical Investigation of Identity Theft Vulnerabilities in Eduroam

A Practical Investigation of Identity Theft Vulnerabilities in Eduroam Sebastian Brenza Andre Pawlowski Christina Pöpper Horst-Görtz Institute for Horst-Görtz Institute for Horst-Görtz Institute for IT-Security IT-Security IT-Security Ruhr-University Bochum Ruhr-University Bochum Ruhr-University Bochum Bochum, Germany Bochum, Germany Bochum, Germany [email protected] [email protected] [email protected] ABSTRACT service at research and educational institutes, Internet ac- Eduroam offers secure access to the Internet at participat- cess at participating institutes has been greatly simplified: ing institutions, using authentication via IEEE 802.1X and Eduroam enables users to roam between participating insti- secure forwarding of authentication data to the authentica- tutions and authenticate with the login data of their home tion server of the user's institution. Due to erroneous con- institutes which is securely forwarded for verification via a figuration manuals and a lack of knowledge on the user side, network of authentication servers to the home institution. though, a big share of client devices lack the required root With their increased popularity in the last couple of years, CA certificate to authenticate the Eduroam network, yet still many networked mobile devices have been configured for being able to access the network. Moreover, deficient soft- Eduroam usage by their users, including laptops, tablets, ware implementations on client devices prevent users from and smartphones. One central point to the security of the the secure execution of the authentication process. Eduroam usage is the proper setup of a root CA certificate In this paper, we present an attack that exploits this fact to verify the authenticity of the network. However, secure and uses the default behavior of wireless devices in order authentication is not given, if deficient software implemen- to capture authentication data. This MITM attack is per- tations do not check the validity of the offered certificate formed in real-time. It is achieved using a modified ver- correctly or client devices are wrongly configured with miss- sion of hostapd, which exploits a compatibility setting of ing CA certificates. If the offered certificate is not checked the widely used supplicant software wpa supplicant. It en- correctly, client devices cannot verify the authenticity of the ables an attacker to authenticate users in EAP-TTLS/PAP network, which opens the door for connecting to rogue access and in EAP-TTLS/MS-CHAPv2 without the necessity of points, also called Evil Twins [12], and man-in-the-middle cracking the user password hash on the fly and thus without (MITM) attacks. This is an issue that also seems to be inducing suspicious delays. In a practical study with sev- known in corporate networks [33]. eral hundred users we could show that more than half of the Institutions participating in Eduroam are supposed to pro- tested devices were vulnerable to the attack. Based on the vide sufficient configuration instructions for their end users results of the study, we propose countermeasures to prevent to allow for the authentic identification of access points at the attack and minimize the amount of vulnerable devices. all times. Unfortunately, at a number of institutions participating in Eduroam, the configuration manuals for users are incomplete or have been so in the past. For example, at Keywords our university the configuration manuals for Android, Mac Network Security; WPA-Enterprise; Eduroam Authentica- OS and iOS devices were missing the instructions for setting tion; EAP; MS-CHAPv2 up the CA certificate. Fixing this simple problem of incomplete configuration manuals does not prevent the problem from prevailing in reality even months later, as we show by 1. INTRODUCTION a practical study involving several hundred participants. Access to scientific and educational resources is important In this paper, we outline a number of problems regarding in research and education. With the start of the Eduroam the authentication structure and processes of the Eduroam network. Although the Extensible Authentication Protocol (EAP) authentication methods used in Eduroam and En- Permission to make digital or hard copies of all or part of this work for per- terprise networks, in particular EAP-TTLS and PEAP, are sonal or classroom use is granted without fee provided that copies are not well-defined and have been thoroughly examined for flaws made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components by security experts, imprecisions in the implementations of this work owned by others than the author(s) must be honored. Abstract- may lead to severe security vulnerabilities. We present a ing with credit is permitted. To copy otherwise, or republish, to post on novel stealthy attack targeting client devices. The attack is servers or to redistribute to lists, requires prior specific permission and/or a based on real-world software and configuration deficiencies. fee. Request permissions from [email protected]. In more details, we use a modified version of the software WiSec'15, June 22 – 26, 2015, New York, NY, USA access point hostapd [20] that exploits the network's trust Copyright is held by the owner/author(s). Publication rights licensed to ACM. ACM 978-1-4503-3623-9/15/06 ...$15.00 structure and enables an attacker to authenticate users on DOI: http://dx.doi.org/10.1145/2766498.2766512 the fly without owning the required username and password . data. This makes it possible to capture authentication data RADIUS international level RADIUS Hierarchy using an evil-twin access point and to gain control over the network traffic of the victim. We investigate the applicability of the attack in a real- national level RADIUS RADIUS world setting and we identify, classify, and evaluate possible countermeasure { both on the side of the client devices as Client Access Visited networks Home Point RADIUS RADIUS on the side of the infrastructure and service provider. 1 identity 2 server In summary, this paper makes the following contributions: 3 certificate secure tunnel 4 authentication data 1. We present a novel attack on a widely used EAP- TTLS/MS-CHAPv2 implementation that allows to by- 5 pass the inner MS-CHAPv2 authentication on devices accept / reject with deficient certificate validation. Figure 1: Authentication Process in Eduroam 2. We investigate the vulnerability of different Android- and Mac OS/iOS-based devices and tablets to this attack and show that they are all vulnerable (in some either authenticated towards the user or both are mutually cases depending on their configuration and user inter- authenticated; in phase 2 the user subsequently authenti- action). cates towards the AS. The authentication is executed as follows (as shown in Figure 1): 3. We report results on a practical study of this vulnerability with about 350 users and more than 500 devices. Phase 1 (Outer Authentication): Of these tested devices, a share of 52 % turned out to be vulnerable to our attack. 1. When a user requests network access, the user's identity is queried by the AP. The user identity is provided 4. We propose multiple client- and infrastructure-side to the AP in the format: [email protected], countermeasures and evaluate their effectiveness where tld is the top-level domain. against the presented attack. To minimize the share of wrongly configured devices, we show an automated 2. The AP forwards the user identity to the home AS way to check device configurations that can be de- of the network, which checks its responsibility for the ployed by institutions offering Eduroam services. user's institution and top-level domain. In case the user requested access to a foreign network, the iden- The rest of this paper is structured as follows: First, the tity is proxied to the next RADIUS AS on national or technical background for the attack is presented in Section 2. international level|based on the user's identity|until Prerequisites and the attacker model are introduced in Sec- the user's home AS is found. tion 3. In Section 4, the approach and characteristics of the attack are described, followed by details on the practical 3. The user's home AS checks if the identity is valid, study in Section 5. Countermeasures are discussed in depth starts tunnel establishment, and answers with its server in Section 6. Finally, related work is presented in Section 7 certificate. The user then validates the server certifi- and we conclude the paper in Section 8. cate and a secure tunnel is established between the user and the AS. 2. PRELIMINARIES Phase 2 (Inner Authentication): This section presents the technical background necessary for the attack described later in this paper. It introduces 4. After the secure tunnel establishment, inner authenti- authentication in Eduroam and IEEE 802.1X along with the cation is executed inside the tunnel between client and targeted tunneled authentication protocols as well as PAP AS, using credentials of the user's home institution. and the MS-CHAPv2 authentication protocol. 5. The user's home AS validates the login data and passes 2.1 Authentication in Eduroam the result to the AP, which subsequently grants or re- Authentication in Eduroam is carried out following the fuses network access. IEEE 802.1X standard for port-based network access control [17]. The system roles Supplicant, Authenticator, and Due to privacy reasons it is encouraged to provide an anony- Authentication Server (AS) correspond in Eduroam to the mous outer identity in phase 1 and the actual/private iden- user's client device, the access point (AP), and the RADIUS tity inside the tunnel in phase 2 [30]. authentication server of the user's home institution [30]. In order to enable users to gain network access using the 2.2 802.1X Protocols same login data and network configuration at each partic- During the authentication process in IEEE 802.1X, au- ipating institution, a hierarchical layer of RADIUS AS is thentication and communication between the client device| introduced.

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