Ramya Jayaram Masti

Der-Yeuan Yu, Aanjhan Ranganathan, Ramya Jayaram Masti et al.

The Location Service (LCS) proposed by the telecommunication industry is an architecture that allows the location of mobile devices to be accessed in various applications. We explore the use of LCS in location-enhanced server authentication, which traditionally relies on certificates. Given recent incidents involving certificate authorities, various techniques to strengthen server authentication were proposed. They focus on improving the certificate validation process, such as pinning, revocation, or multi-path probing. In this paper, we propose using the server's geographic location as a second factor of its authenticity. Our solution, SALVE, achieves location-based server authentication by using secure DNS resolution and by leveraging LCS for location measurements. We develop a TLS extension that enables the client to verify the server's location in addition to its certificate. Successful server authentication therefore requires a valid certificate and the server's presence at a legitimate geographic location, e.g., on the premises of a data center. SALVE prevents server impersonation by remote adversaries with mis-issued certificates or stolen private keys of the legitimate server. We develop a prototype implementation and our evaluation in real-world settings shows that it incurs minimal impact to the average server throughput. Our solution is backward compatible and can be integrated with existing approaches for improving server authentication in TLS.

Ramya Jayaram Masti, Devendra Rai, Aanjhan Ranganathan et al.

Side channels remain a challenge to information flow control and security in modern computing platforms. Resource partitioning techniques that minimise the number of shared resources among processes are often used to address this challenge. In this work, we focus on multi-core platforms and we demonstrate that even seemingly strong isolation techniques based on dedicated cores and memory can be circumvented through the use of thermal side channels. Specifically, we show that the processor core temperature can be used both as a side channel as well as a covert communication channel even when the system implements strong spatial and temporal partitioning. Our experiments on an x86-based platform demonstrate covert thermal channels that achieve up to 12.5 bps and a weak side channel that can detect processes executed on neighbouring cores. This work therefore shows a limitation in the isolation that can be achieved on existing multi-core systems.

Claudio Marforio, Ramya Jayaram Masti, Claudio Soriente et al.

Phishing in mobile applications is a relevant threat with successful attacks reported in the wild. In such attacks, malicious mobile applications masquerade as legitimate ones to steal user credentials. In this paper we categorize application phishing attacks in mobile platforms and possible countermeasures. We show that personalized security indicators can help users to detect phishing attacks and have very little deployment cost. Personalized security indicators, however, rely on the user alertness to detect phishing attacks. Previous work in the context of website phishing has shown that users tend to ignore the absence of security indicators and fall victim of the attacker. Consequently, the research community has deemed personalized security indicators as an ineffective phishing detection mechanism. We evaluate personalized security indicators as a phishing detection solution in the context of mobile applications. We conducted a large-scale user study where a significant amount of participants that used personalized security indicators were able to detect phishing. All participants that did not use indicators could not detect the attack and entered their credentials to a phishing application. We found the difference in the attack detection ratio to be statistically significant. Personalized security indicators can, therefore, help phishing detection in mobile applications and their reputation as an anti-phishing mechanism should be reconsidered. We also propose a novel protocol to setup personalized security indicators under a strong adversarial model and provide details on its performance and usability.