Understanding and Enforcing Opacity

Abstract—This paper puts a spotlight on the specification and enforcement of opacity, a security policy for protecting sensitive properties of system behavior. We illustrate the fine granularity of the opacity policy by location privacy and privacy-preserving aggregation scenarios. We present a frame-work for opacity and explore its key differences and formal connections with such well-known information-flow models as noninterference, knowledge-based security, and declassifica-tion. Our results are machine-checked and parameterized in the observational power of the attacker, including progress-insensitive, progress-sensitive, and timing-sensitive attackers. We present two approaches to enforcing opacity: a whitebox monitor and a blackbox sampling-based enforcement. We report on experiments with prototypes that utilize state-of-the-art Satisfiability Modulo Theories (SMT) solvers and the random testing tool QuickCheck to establish opacity for the location and aggregation-based scenarios. I

On the road with third-party apps: Security analysis of an in-vehicle app platform

Digitalization has revolutionized the automotive industry. Modern cars are equipped with powerful Internetconnected infotainment systems, comparable to tablets and smartphones. Recently, several car manufacturers have announced the upcoming possibility to install third-party apps onto these infotainment systems. The prospect of running third-party code on a device that is integrated into a safety critical in-vehicle system raises serious concerns for safety, security, and user privacy. This paper investigates these concerns of in-vehicle apps. We focus on apps for the Android Automotive operating system which several car manufacturers have opted to use. While the architecture inherits much from regular Android, we scrutinize the adequateness of its security mechanisms with respect to the in-vehicle setting, particularly affecting road safety and user privacy. We investigate the attack surface and vulnerabilities for third-party in-vehicle apps. We analyze and suggest enhancements to such traditional Android mechanisms as app permissions and API control. Further, we investigate operating system support and how static and dynamic analysis can aid automatic vetting of in-vehicle apps. We develop AutoTame, a tool for vehicle-specific code analysis. We report on a case study of the countermeasures with a Spotify app using emulators and physical test beds from Volvo Cars

Hardening the security analysis of browser extensions

Browser extensions boost the browsing experience by a range of features from automatic translation and grammar correction to password management, ad blocking, and remote desktops. Yet the power of extensions poses significant privacy and security challenges because extensions can be malicious and/or vulnerable. We observe that there are gaps in the previous work on analyzing the security of browser extensions and present a systematic study of attack entry points in the browser extension ecosystem. Our study reveals novel password stealing, traffic stealing, and inter-extension attacks. Based on a combination of static and dynamic analysis we show how to discover extension attacks, both known and novel ones, and study their prevalence in the wild. We show that 1,349 extensions are vulnerable to inter-extension attacks leading to XSS. Our empirical study uncovers a remarkable cluster of "New Tab"extensions where 4,410 extensions perform traffic stealing attacks. We suggest several avenues for the countermeasures against the uncovered attacks, ranging from refining the permission model to mitigating the attacks by declarations in manifest files

03411 Abstracts Collection -- Language Based Security

From October 5th to 10th 2003,the Dagstuhl Seminar 03411 ``Language Based security\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar are put together in this paper

Nontransitive Policies Transpiled

Nontransitive Noninterference (NTNI) and Nontransitive Types (NTT) are a new security condition and enforcement for policies which, in contrast to Denning\u27s classical lattice model, assume no transitivity of the underlying flow relation. Nontransitive security policies are a natural fit for coarse-grained information-flow control where labels are specified at module rather than variable level of granularity.While the nontransitive and transitive policies pursue different goals and have different intuitions, this paper demonstrates that nontransitive noninterference can in fact be reduced to classical transitive noninterference. We develop a lattice encoding that establishes a precise relation between NTNI and classical noninterference. Our results make it possible to clearly position the new NTNI characterization with respect to the large body of work on noninterference. Further, we devise a lightweight program transformation that leverages standard flow-sensitive information-flow analyses to enforce nontransitive policies. We demonstrate several immediate benefits of our approach, both theoretical and practical. First, we improve the permissiveness over (while retaining the soundness of) the nonstandard NTT enforcement. Second, our results naturally generalize to a language with intermediate inputs and outputs. Finally, we demonstrate the practical benefits by utilizing state-of-the-art flow-sensitive tool JOANA to enforce nontransitive policies for Java programs

07091 Abstracts Collection -- Mobility, Ubiquity and Security

From 25.02.2007 to 02.03.2007, the Dagstuhl Seminar 07091 ``Mobility, Ubiquity and Security\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Are chrome extensions compliant with the spirit of least privilege?

Extensions are small applications installed by users and enrich the user experience of browsing the Internet. Browsers expose a set of restricted APIs to extensions. To be used, extensions need to list the permissions associated with these APIs in a mandatory extension file named manifest. In particular, Chrome’s permission ecosystem was designed in the spirit of the least privilege. Yet, this paper demonstrates that 39.8% of the analyzed extensions provided by the official Web Store are compliant with the spirit of least privilege. Also, we develop: (1) a browser extension to make aware regular users of the permissions the extensions they install; (2) a web app where extensions developers can check whether their extensions are compliant with the spirit of the least privileged; and (3) a set of scripts that can be part of the vendors’ acceptance criteria such that when developers upload their extensions to the official repositories, the scripts automatically analyze the extensions and generate a report about the permissions and the usage