Verified Correctness and Security of mbedTLS HMAC-DRBG

We have formalized the functional specification of HMAC-DRBG (NIST 800-90A), and we have proved its cryptographic security--that its output is pseudorandom--using a hybrid game-based proof. We have also proved that the mbedTLS implementation (C program) correctly implements this functional specification. That proof composes with an existing C compiler correctness proof to guarantee, end-to-end, that the machine language program gives strong pseudorandomness. All proofs (hybrid games, C program verification, compiler, and their composition) are machine-checked in the Coq proof assistant. Our proofs are modular: the hybrid game proof holds on any implementation of HMAC-DRBG that satisfies our functional specification. Therefore, our functional specification can serve as a high-assurance reference.Comment: Appearing in CCS '1

Zero permission android applications - attacks and defenses

Google advertises the Android permission framework as one of the core security features present on its innovative and flexible mobile platform. The permissions are a means to control access to restricted AP/s and system resources. However, there are Android applications which do not request permissions at all.In this paper, we analyze the repercussions of installing an Android application that does not include any permission and the types of sensitive information that can be accessed by such an application. We found that even app/icaaons with no permissions are able to access sensitive information (such the device ID) and transmit it to third-parties

Trustworthiness in Mobile Cyber Physical Systems

Computing and communication capabilities are increasingly embedded in diverse objects and structures in the physical environment. They will link the ‘cyberworld’ of computing and communications with the physical world. These applications are called cyber physical systems (CPS). Obviously, the increased involvement of real-world entities leads to a greater demand for trustworthy systems. Hence, we use "system trustworthiness" here, which can guarantee continuous service in the presence of internal errors or external attacks. Mobile CPS (MCPS) is a prominent subcategory of CPS in which the physical component has no permanent location. Mobile Internet devices already provide ubiquitous platforms for building novel MCPS applications. The objective of this Special Issue is to contribute to research in modern/future trustworthy MCPS, including design, modeling, simulation, dependability, and so on. It is imperative to address the issues which are critical to their mobility, report significant advances in the underlying science, and discuss the challenges of development and implementation in various applications of MCPS

Resolving the predicament of android custom permissions

Android leverages a set of system permissions to protect platform resources. At the same time, it allows untrusted third-party applications to declare their own custom permissions to regulate access to app components. However, Android treats custom permissions the same way as system permissions even though they are declared by entities of different trust levels. In this work, we describe two new classes of vulnerabilities that arise from the ‘predicament’ created by mixing system and custom permissions in Android. These have been acknowledged as serious security flaws by Google and we demonstrate how they can be exploited in practice to gain unauthorized access to platform resources and to compromise popular Android apps. To address the shortcomings of the system, we propose a new modular design called Cusper for the Android permission model. Cusper separates the management of system and custom permissions and introduces a backward-compatible naming convention for custom permissions to prevent custom permission spoofing. We validate the correctness of Cusper by 1) introducing the first formal model of Android runtime permissions, 2) extending it to describe Cusper, and 3) formally showing that key security properties that can be violated in the current permission model are always satisfied in Cusper. To demonstrate Cusper’s practicality, we implemented it in the Android platform and showed that it is both effective and efficient

Addressing consumerisation of IT risks with nudging

In this work we address the main issues of Information Technology (IT) consumerisation that are related to security risks, and vulnerabilities of devices used within Bring Your Own Device (BYOD) strategy in particular. We propose a ‘soft’ mitigation strategy for user actions based on nudging, widely applied to health and social behaviour influence. In particular, we propose a complementary, less strict, more flexible Information Security policies, based on risk assessment of device vulnerabilities and threats to corporate data and devices, combined with a strategy of influencing security behaviour by nudging. We argue that nudging, by taking into account the context of the decision-making environment, and the fact that the employee may be in better position to make a more appropriate decision, may be more suitable than strict policies in situations of uncertainty of security-related decisions. Several examples of nudging are considered for different tested and potential scenarios in security context

Addressing consumerisation of IT risks with nudging

In this work we address the main issues of Information Technology (IT) consumerisation that are related to security risks, and vulnerabilities of devices used within Bring Your Own Device (BYOD) strategy in particular. We propose a ‘soft’ mitigation strategy for user actions based on nudging, widely applied to health and social behaviour influence. In particular, we propose a complementary, less strict, more flexible Information Security policies, based on risk assessment of device vulnerabilities and threats to corporate data and devices, combined with a strategy of influencing security behaviour by nudging. We argue that nudging, by taking into account the context of the decision-making environment, and the fact that the employee may be in better position to make a more appropriate decision, may be more suitable than strict policies in situations of uncertainty of security-related decisions. Several examples of nudging are considered for different tested and potential scenarios in security context

Addressing consumerization of IT risks with nudging

In this work we address the main issues of Information Technology (IT) consumerization that are related to security risks, and vulnerabilities of devices used within Bring Your Own Device (BYOD) strategy in particular. We propose a ‘soft’ mitigation strategy for user actions based on nudging, widely applied to health and social behavior influence. In particular, we propose a complementary, less strict, more flexible Information Security policies, based on risk assessment of device vulnerabilities and threats to corporate data and devices, combined with a strategy of influencing security behavior by nudging. We argue that nudging, by taking into account the context of the decision-making environment, and the fact that the employee may be in better position to make a more appropriate decision, may be more suitable than strict policies in situations of uncertainty of security-related decisions. Several examples of nudging are considered for different tested and potential scenarios in security context

Addressing consumerization of IT risks with nudging

In this work we address the main issues of Information Technology (IT) consumerization that are related to security risks, and vulnerabilities of devices used within Bring Your Own Device (BYOD) strategy in particular. We propose a ‘soft’ mitigation strategy for user actions based on nudging, widely applied to health and social behavior influence. In particular, we propose a complementary, less strict, more flexible Information Security policies, based on risk assessment of device vulnerabilities and threats to corporate data and devices, combined with a strategy of influencing security behavior by nudging. We argue that nudging, by taking into account the context of the decision-making environment, and the fact that the employee may be in better position to make a more appropriate decision, may be more suitable than strict policies in situations of uncertainty of security-related decisions. Several examples of nudging are considered for different tested and potential scenarios in security context