Visible to the public Biblio

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2021-07-08
Kunz, Immanuel, Schneider, Angelika, Banse, Christian.  2020.  Privacy Smells: Detecting Privacy Problems in Cloud Architectures. 2020 IEEE 19th International Conference on Trust, Security and Privacy in Computing and Communications (TrustCom). :1324—1331.
Many organizations are still reluctant to move sensitive data to the cloud. Moreover, data protection regulations have established considerable punishments for violations of privacy and security requirements. Privacy, however, is a concept that is difficult to measure and to demonstrate. While many privacy design strategies, tactics and patterns have been proposed for privacy-preserving system design, it is difficult to evaluate an existing system with regards to whether these strategies have or have not appropriately been implemented. In this paper we propose indicators for a system's non-compliance with privacy design strategies, called privacy smells. To that end we first identify concrete metrics that measure certain aspects of existing privacy design strategies. We then define smells based on these metrics and discuss their limitations and usefulness. We identify these indicators on two levels of a cloud system: the data flow level and the access control level. Using a cloud system built in Microsoft Azure we show how the metrics can be measured technically and discuss the differences to other cloud providers, namely Amazon Web Services and Google Cloud Platform. We argue that while it is difficult to evaluate the privacy-awareness in a cloud system overall, certain privacy aspects in cloud systems can be mapped to useful metrics that can indicate underlying privacy problems. With this approach we aim at enabling cloud users and auditors to detect deep-rooted privacy problems in cloud systems.
2021-03-29
Pieper, P., Herdt, V., Große, D., Drechsler, R..  2020.  Dynamic Information Flow Tracking for Embedded Binaries using SystemC-based Virtual Prototypes. 2020 57th ACM/IEEE Design Automation Conference (DAC). :1—6.

Avoiding security vulnerabilities is very important for embedded systems. Dynamic Information Flow Tracking (DIFT) is a powerful technique to analyze SW with respect to security policies in order to protect the system against a broad range of security related exploits. However, existing DIFT approaches either do not exist for Virtual Prototypes (VPs) or fail to model complex hardware/software interactions.In this paper, we present a novel approach that enables early and accurate DIFT of binaries targeting embedded systems with custom peripherals. Leveraging the SystemC framework, our DIFT engine tracks accurate data flow information alongside the program execution to detect violations of security policies at run-time. We demonstrate the effectiveness and applicability of our approach by extensive experiments.

2020-06-08
Sahabandu, Dinuka, Moothedath, Shana, Bushnell, Linda, Poovendran, Radha, Aller, Joey, Lee, Wenke, Clark, Andrew.  2019.  A Game Theoretic Approach for Dynamic Information Flow Tracking with Conditional Branching. 2019 American Control Conference (ACC). :2289–2296.
In this paper, we study system security against Advanced Persistent Threats (APTs). APTs are stealthy and persistent but APTs interact with system and introduce information flows in the system as data-flow and control-flow commands. Dynamic Information Flow Tracking (DIFT) is a promising detection mechanism against APTs which taints suspicious input sources in the system and performs online security analysis when a tainted information is used in unauthorized manner. Our objective in this paper is to model DIFT that handle data-flow and conditional branches in the program that arise from control-flow commands. We use game theoretic framework and provide the first analytical model of DIFT with data-flow and conditional-branch tracking. Our game model which is an undiscounted infinite-horizon stochastic game captures the interaction between APTs and DIFT and the notion of conditional branching. We prove that the best response of the APT is a maximal reachability probability problem and provide a polynomial-time algorithm to find the best response by solving a linear optimization problem. We formulate the best response of the defense as a linear optimization problem and show that an optimal solution to the linear program returns a deterministic optimal policy for the defense. Since finding Nash equilibrium for infinite-horizon undiscounted stochastic games is computationally difficult, we present a nonlinear programming based polynomial-time algorithm to find an E-Nash equilibrium. Finally, we perform experimental analysis of our algorithm on real-world data for NetRecon attack augmented with conditional branching.
2020-03-09
Sion, Laurens, Van Landuyt, Dimitri, Wuyts, Kim, Joosen, Wouter.  2019.  Privacy Risk Assessment for Data Subject-Aware Threat Modeling. 2019 IEEE Security and Privacy Workshops (SPW). :64–71.
Regulatory efforts such as the General Data Protection Regulation (GDPR) embody a notion of privacy risk that is centered around the fundamental rights of data subjects. This is, however, a fundamentally different notion of privacy risk than the one commonly used in threat modeling which is largely agnostic of involved data subjects. This mismatch hampers the applicability of privacy threat modeling approaches such as LINDDUN in a Data Protection by Design (DPbD) context. In this paper, we present a data subject-aware privacy risk assessment model in specific support of privacy threat modeling activities. This model allows the threat modeler to draw upon a more holistic understanding of privacy risk while assessing the relevance of specific privacy threats to the system under design. Additionally, we propose a number of improvements to privacy threat modeling, such as enriching Data Flow Diagram (DFD) system models with appropriate risk inputs (e.g., information on data types and involved data subjects). Incorporation of these risk inputs in DFDs, in combination with a risk estimation approach using Monte Carlo simulations, leads to a more comprehensive assessment of privacy risk. The proposed risk model has been integrated in threat modeling tool prototype and validated in the context of a realistic eHealth application.
2020-02-24
Maunero, Nicoló, Prinetto, Paolo, Roascio, Gianluca.  2019.  CFI: Control Flow Integrity or Control Flow Interruption? 2019 IEEE East-West Design Test Symposium (EWDTS). :1–6.

Runtime memory vulnerabilities, especially present in widely used languages as C and C++, are exploited by attackers to corrupt code pointers and hijack the execution flow of a program running on a target system to force it to behave abnormally. This is the principle of modern Code Reuse Attacks (CRAs) and of famous attack paradigms as Return-Oriented Programming (ROP) and Jump-Oriented Programming (JOP), which have defeated the previous defenses against malicious code injection such as Data Execution Prevention (DEP). Control-Flow Integrity (CFI) is a promising approach to protect against such runtime attacks. Recently, many CFI solutions have been proposed, with both hardware and software implementations. But how can a defense based on complying with a graph calculated a priori efficiently deal with something unpredictable as exceptions and interrupt requests? The present paper focuses on this dichotomy by analysing some of the CFI-based defenses and showing how the unexpected trigger of an interrupt and the sudden execution of an Interrupt Service Routine (ISR) can circumvent them.

2020-01-27
Li, Zhangtan, Cheng, Liang, Zhang, Yang.  2019.  Tracking Sensitive Information and Operations in Integrated Clinical Environment. 2019 18th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/13th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE). :192–199.
Integrated Clinical Environment (ICE) is a standardized framework for achieving device interoperability in medical cyber-physical systems. The ICE utilizes high-level supervisory apps and a low-level communication middleware to coordinate medical devices. The need to design complex ICE systems that are both safe and effective has presented numerous challenges, including interoperability, context-aware intelligence, security and privacy. In this paper, we present a data flow analysis framework for the ICE systems. The framework performs the combination of static and dynamic analysis for the sensitive data and operations in the ICE systems. Our experiments demonstrate that the data flow analysis framework can record how the medical devices transmit sensitive data and perform misuse detection by tracing the runtime context of the sensitive operations.
Schmeidl, Florian, Nazzal, Bara, Alalfi, Manar H..  2019.  Security Analysis for SmartThings IoT Applications. 2019 IEEE/ACM 6th International Conference on Mobile Software Engineering and Systems (MOBILESoft). :25–29.
This paper presents a fully automated static analysis approach and a tool, Taint-Things, for the identification of tainted flows in SmartThings IoT apps. Taint-Things accurately identified all tainted flows reported by one of the state-of the-art tools with at least 4 times improved performance. In addition, our approach reports potential vulnerable tainted flow in a form of a concise security slice, which could provide security auditors with an effective and precise tool to pinpoint security issues in SmartThings apps under test.
2019-09-26
Pfeffer, T., Herber, P., Druschke, L., Glesner, S..  2018.  Efficient and Safe Control Flow Recovery Using a Restricted Intermediate Language. 2018 IEEE 27th International Conference on Enabling Technologies: Infrastructure for Collaborative Enterprises (WETICE). :235-240.

Approaches for the automatic analysis of security policies on source code level cannot trivially be applied to binaries. This is due to the lacking high-level semantics of low-level object code, and the fundamental problem that control-flow recovery from binaries is difficult. We present a novel approach to recover the control-flow of binaries that is both safe and efficient. The key idea of our approach is to use the information contained in security mechanisms to approximate the targets of computed branches. To achieve this, we first define a restricted control transition intermediate language (RCTIL), which restricts the number of possible targets for each branch to a finite number of given targets. Based on this intermediate language, we demonstrate how a safe model of the control flow can be recovered without data-flow analyses. Our evaluation shows that that makes our solution more efficient than existing solutions.

2017-07-24
Smullen, Daniel, Breaux, Travis D..  2016.  Modeling, Analyzing, and Consistency Checking Privacy Requirements Using Eddy. Proceedings of the Symposium and Bootcamp on the Science of Security. :118–120.

Eddy is a privacy requirements specification language that privacy analysts can use to express requirements over data practices; to collect, use, transfer and retain personal and technical information. The language uses a simple SQL-like syntax to express whether an action is permitted or prohibited, and to restrict those statements to particular data subjects and purposes. Eddy also supports the ability to express modifications on data, including perturbation, data append, and redaction. The Eddy specifications are compiled into Description Logic to automatically detect conflicting requirements and to trace data flows within and across specifications. Conflicts are highlighted, showing which rules are in conflict (expressing prohibitions and rights to perform the same action on equivalent interpretations of the same data, data subjects, or purposes), and what definitions caused the rules to conflict. Each specification can describe an organization's data practices, or the data practices of specific components in a software architecture.

2017-05-30
Gao, Fengjuan, Chen, Tianjiao, Wang, Yu, Situ, Lingyun, Wang, Linzhang, Li, Xuandong.  2016.  Carraybound: Static Array Bounds Checking in C Programs Based on Taint Analysis. Proceedings of the 8th Asia-Pacific Symposium on Internetware. :81–90.

C programming language never performs automatic bounds checking in order to speed up execution. But bounds checking is absolutely necessary in any program. Because if a variable is out-of-bounds, some serious errors may occur during execution, such as endless loop or buffer overflows. When there are arrays used in a program, the index of an array must be within the boundary of the array. But programmers always miss the array bounds checking or do not perform a correct array bounds checking. In this paper, we perform static analysis based on taint analysis and data flow analysis to detect which arrays do not have correct array bounds checking in the program. And we implement an automatic static tool, Carraybound. And the experimental results show that Carraybound can work effectively and efficiently.

2015-05-05
Wenmin Xiao, Jianhua Sun, Hao Chen, Xianghua Xu.  2014.  Preventing Client Side XSS with Rewrite Based Dynamic Information Flow. Parallel Architectures, Algorithms and Programming (PAAP), 2014 Sixth International Symposium on. :238-243.

This paper presents the design and implementation of an information flow tracking framework based on code rewrite to prevent sensitive information leaks in browsers, combining the ideas of taint and information flow analysis. Our system has two main processes. First, it abstracts the semantic of JavaScript code and converts it to a general form of intermediate representation on the basis of JavaScript abstract syntax tree. Second, the abstract intermediate representation is implemented as a special taint engine to analyze tainted information flow. Our approach can ensure fine-grained isolation for both confidentiality and integrity of information. We have implemented a proof-of-concept prototype, named JSTFlow, and have deployed it as a browser proxy to rewrite web applications at runtime. The experiment results show that JSTFlow can guarantee the security of sensitive data and detect XSS attacks with about 3x performance overhead. Because it does not involve any modifications to the target system, our system is readily deployable in practice.