Visible to the public Biblio

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Qian, K., Parizi, R. M., Lo, D..  2018.  OWASP Risk Analysis Driven Security Requirements Specification for Secure Android Mobile Software Development. 2018 IEEE Conference on Dependable and Secure Computing (DSC). :1—2.
The security threats to mobile applications are growing explosively. Mobile apps flaws and security defects open doors for hackers to break in and access sensitive information. Defensive requirements analysis should be an integral part of secure mobile SDLC. Developers need to consider the information confidentiality and data integrity, to verify the security early in the development lifecycle rather than fixing the security holes after attacking and data leaks take place. Early eliminating known security vulnerabilities will help developers increase the security of apps and reduce the likelihood of exploitation. However, many software developers lack the necessary security knowledge and skills at the development stage, and that's why Secure Mobile Software Development education is very necessary for mobile software engineers. In this paper, we propose a guided security requirement analysis based on OWASP Mobile Top ten security risk recommendations for Android mobile software development and its traceability of the developmental controls in SDLC. Building secure apps immune to the OWASP Mobile Top ten risks would be an effective approach to provide very useful mobile security guidelines.
Singh, M., Butakov, S., Jaafar, F..  2018.  Analyzing Overhead from Security and Administrative Functions in Virtual Environment. 2018 International Conference on Platform Technology and Service (PlatCon). :1—6.
The paper provides an analysis of the performance of an administrative component that helps the hypervisor to manage the resources of guest operating systems under fluctuation workload. The additional administrative component provides an extra layer of security to the guest operating systems and system as a whole. In this study, an administrative component was implemented by using Xen-hypervisor based para-virtualization technique and assigned some additional roles and responsibilities that reduce hypervisor workload. The study measured the resource utilizations of an administrative component when excessive input/output load passes passing through the system. Performance was measured in terms of bandwidth and CPU utilisation Based on the analysis of administrative component performance recommendations have been provided with the goal to improve system availability. Recommendations included detection of the performance saturation point that indicates the necessity to start load balancing procedures for the administrative component in the virtualized environment.
Jaiswal, M., Malik, Y., Jaafar, F..  2018.  Android gaming malware detection using system call analysis. 2018 6th International Symposium on Digital Forensic and Security (ISDFS). :1—5.
Android operating systems have become a prime target for attackers as most of the market is currently dominated by Android users. The situation gets worse when users unknowingly download or sideload cloning applications, especially gaming applications that look like benign games. In this paper, we present, a dynamic Android gaming malware detection system based on system call analysis to classify malicious and legitimate games. We performed the dynamic system call analysis on normal and malicious gaming applications while applications are in execution state. Our analysis reveals the similarities and differences between benign and malware game system calls and shows how dynamically analyzing the behavior of malicious activity through system calls during runtime makes it easier and is more effective to detect malicious applications. Experimental analysis and results shows the efficiency and effectiveness of our approach.
Maksutov, A. A., Dmitriev, S. O., Lysenkov, V. I., Valter, D. A..  2018.  Mobile bootloader with security features. 2018 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus). :335—338.
Modern mobile operating systems store a lot of excessive information that can be used against its owner or organization, like a call history or various system logs. This article describes a universal way of preventing any mobile operating system or application from saving its data in device's internal storage without reducing their functionality. The goal of this work is creation of a software that solves the described problem and works on the bootloading stage. A general algorithm of the designed software, along with its main solutions and requirements, is presented in this paper. Hardware requirement, software testing results and general applications of this software are also listed in this paper.
Wang, H., Li, J., Liu, D..  2018.  Research on Operating Data Analysis for Enterprise Intranet Information Security Risk Assessment. 2018 12th IEEE International Conference on Anti-counterfeiting, Security, and Identification (ASID). :72—76.
Operating data analysis means to analyze the operating system logs, user operation logs, various types of alarms and security relevant configurations, etc. The purpose is to find whether there is an attack event, suspicious behaviors or improper configurations. It is an important part of risk assessment for enterprise intranet. However, due to the lack of information security knowledge or relevant experience, many people do not know how to properly implement it. In this article, we provided guidance on conducting operating data analysis and how to determine the security risk with the analysis results.
Benhani, E. M., Bossuet, L..  2018.  DVFS as a Security Failure of TrustZone-enabled Heterogeneous SoC. 2018 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS). :489—492.
Today, most embedded systems use Dynamic Voltage and Frequency Scaling (DVFS) to minimize energy consumption and maximize performance. The DVFS technique works by regulating the important parameters that govern the amount of energy consumed in a system, voltage and frequency. For the implementation of this technique, the operating system (OS) includes software applications that dynamically control a voltage regulator or a frequency regulator or both. In this paper, we demonstrate for the first time a malicious use of the frequency regulator against a TrustZone-enabled System-on-Chip (SoC). We demonstrate a use of frequency scaling to create covert channel in a TrustZone-enabled heterogeneous SoC. We present four proofs of concept to transfer sensitive data from a secure entity in the SoC to a non-secure one. The first proof of concept is from a secure ARM core to outside of SoC. The second is from a secure ARM core to a non-secure one. The third is from a non-trusted third party IP embedded in the programmable logic part of the SoC to a non-secure ARM core. And the last proof of concept is from a secure third party IP to a non-secure ARM core.
Dar, Muneer Ahmad, Nisar Bukhari, Syed, Khan, Ummer Iqbal.  2018.  Evaluation of Security and Privacy of Smartphone Users. 2018 Fourth International Conference on Advances in Electrical, Electronics, Information, Communication and Bio-Informatics (AEEICB). :1–4.

The growing use of smart phones has also given opportunity to the intruders to create malicious apps thereby the security and privacy concerns of a novice user has also grown. This research focuses on the privacy concerns of a user who unknowingly installs a malicious apps created by the programmer. In this paper we created an attack scenario and created an app capable of compromising the privacy of the users. After accepting all the permissions by the user while installing the app, the app allows us to track the live location of the Android device and continuously sends the GPS coordinates to the server. This spying app is also capable of sending the call log details of the user. This paper evaluates two leading smart phone operating systems- Android and IOS to find out the flexibility provided by the two operating systems to their programmers to create the malicious apps.

Li, D., Zhang, Z., Liao, W., Xu, Z..  2018.  KLRA: A Kernel Level Resource Auditing Tool For IoT Operating System Security. 2018 IEEE/ACM Symposium on Edge Computing (SEC). :427-432.

Nowadays, the rapid development of the Internet of Things facilitates human life and work, while it also brings great security risks to the society due to the frequent occurrence of various security issues. IoT device has the characteristics of large-scale deployment and single responsibility application, which makes it easy to cause a chain reaction and results in widespread privacy leakage and system security problems when the software vulnerability is identified. It is difficult to guarantee that there is no security hole in the IoT operating system which is usually designed for MCU and has no kernel mode. An alternative solution is to identify the security issues in the first time when the system is hijacked and suspend the suspicious task before it causes irreparable damage. This paper proposes KLRA (A Kernel Level Resource Auditing Tool) for IoT Operating System Security This tool collects the resource-sensitive events in the kernel and audit the the resource consumption pattern of the system at the same time. KLRA can take fine-grained events measure with low cost and report the relevant security warning in the first time when the behavior of the system is abnormal compared with daily operations for the real responsibility of this device. KLRA enables the IoT operating system for MCU to generate the security early warning and thereby provides a self-adaptive heuristic security mechanism for the entire IoT system.

Sokolov, A. N., Barinov, A. E., Antyasov, I. S., Skurlaev, S. V., Ufimtcev, M. S., Luzhnov, V. S..  2018.  Hardware-Based Memory Acquisition Procedure for Digital Investigations of Security Incidents in Industrial Control Systems. 2018 Global Smart Industry Conference (GloSIC). :1-7.

The safety of industrial control systems (ICS) depends not only on comprehensive solutions for protecting information, but also on the timing and closure of vulnerabilities in the software of the ICS. The investigation of security incidents in the ICS is often greatly complicated by the fact that malicious software functions only within the computer's volatile memory. Obtaining the contents of the volatile memory of an attacked computer is difficult to perform with a guaranteed reliability, since the data collection procedure must be based on a reliable code (the operating system or applications running in its environment). The paper proposes a new instrumental method for obtaining the contents of volatile memory, general rules for implementing the means of collecting information stored in memory. Unlike software methods, the proposed method has two advantages: firstly, there is no problem in terms of reading the parts of memory, blocked by the operating system, and secondly, the resulting contents are not compromised by such malicious software. The proposed method is relevant for investigating security incidents of ICS and can be used in continuous monitoring systems for the security of ICS.

Dong, Xiaowan, Shen, Zhuojia, Criswell, John, Cox, Alan, Dwarkadas, Sandhya.  2018.  Spectres, Virtual Ghosts, and Hardware Support. Proceedings of the 7th International Workshop on Hardware and Architectural Support for Security and Privacy. :5:1–5:9.

Side-channel attacks, such as Spectre and Meltdown, that leverage speculative execution pose a serious threat to computing systems. Worse yet, such attacks can be perpetrated by compromised operating system (OS) kernels to bypass defenses that protect applications from the OS kernel. This work evaluates the performance impact of three different defenses against in-kernel speculation side-channel attacks within the context of Virtual Ghost, a system that protects user data from compromised OS kernels: Intel MPX bounds checks, which require a memory fence; address bit-masking and testing, which creates a dependence between the bounds check and the load/store; and the use of separate virtual address spaces for applications, the OS kernel, and the Virtual Ghost virtual machine, forcing a speculation boundary. Our results indicate that an instrumentation-based bit-masking approach to protection incurs the least overhead by minimizing speculation boundaries. Our work also highlights possible improvements to Intel MPX that could help mitigate speculation side-channel attacks at a lower cost.

Horton, M., Samanta, B., Reid, C., Chen, L., Kadlec, C..  2018.  Development of a Secure, Heterogeneous Cloud Robotics Infrastructure: Implementing a Mesh VPN and Robotic File System Security Practices. SoutheastCon 2018. :1–8.

Robotics and the Internet of Things (IoT) are enveloping our society at an exponential rate due to lessening costs and better availability of hardware and software. Additionally, Cloud Robotics and Robot Operating System (ROS) can offset onboard processing power. However, strong and fundamental security practices have not been applied to fully protect these systems., partially negating the benefits of IoT. Researchers are therefore tasked with finding ways of securing communications and systems. Since security and convenience are oftentimes at odds, securing many heterogeneous components without compromising performance can be daunting. Protecting systems from attacks and ensuring that connections and instructions are from approved devices, all while maintaining the performance is imperative. This paper focuses on the development of security best practices and a mesh framework with an open-source, multipoint-to-multipoint virtual private network (VPN) that can tie Linux, Windows, IOS., and Android devices into one secure fabric, with heterogeneous mobile robotic platforms running ROSPY in a secure cloud robotics infrastructure.

van der Veen, Victor, Andriesse, Dennis, Stamatogiannakis, Manolis, Chen, Xi, Bos, Herbert, Giuffrdia, Cristiano.  2017.  The Dynamics of Innocent Flesh on the Bone: Code Reuse Ten Years Later. Proceedings of the 2017 ACM SIGSAC Conference on Computer and Communications Security. :1675–1689.

In 2007, Shacham published a seminal paper on Return-Oriented Programming (ROP), the first systematic formulation of code reuse. The paper has been highly influential, profoundly shaping the way we still think about code reuse today: an attacker analyzes the "geometry" of victim binary code to locate gadgets and chains these to craft an exploit. This model has spurred much research, with a rapid progression of increasingly sophisticated code reuse attacks and defenses over time. After ten years, the common perception is that state-of-the-art code reuse defenses are effective in significantly raising the bar and making attacks exceedingly hard. In this paper, we challenge this perception and show that an attacker going beyond "geometry" (static analysis) and considering the "dynamics" (dynamic analysis) of a victim program can easily find function call gadgets even in the presence of state-of-the-art code-reuse defenses. To support our claims, we present Newton, a run-time gadget-discovery framework based on constraint-driven dynamic taint analysis. Newton can model a broad range of defenses by mapping their properties into simple, stackable, reusable constraints, and automatically generate gadgets that comply with these constraints. Using Newton, we systematically map and compare state-of-the-art defenses, demonstrating that even simple interactions with popular server programs are adequate for finding gadgets for all state-of-the-art code-reuse defenses. We conclude with an nginx case study, which shows that a Newton-enabled attacker can craft attacks which comply with the restrictions of advanced defenses, such as CPI and context-sensitive CFI.

Wang, Shuai, Wang, Wenhao, Bao, Qinkun, Wang, Pei, Wang, XiaoFeng, Wu, Dinghao.  2017.  Binary Code Retrofitting and Hardening Using SGX. Proceedings of the 2017 Workshop on Forming an Ecosystem Around Software Transformation. :43–49.

Trusted Execution Environment (TEE) is designed to deliver a safe execution environment for software systems. Intel Software Guard Extensions (SGX) provides isolated memory regions (i.e., SGX enclaves) to protect code and data from adversaries in the untrusted world. While existing research has proposed techniques to execute entire executable files inside enclave instances by providing rich sets of OS facilities, one notable limitation of these techniques is the unavoidably large size of Trusted Computing Base (TCB), which can potentially break the principle of least privilege. In this work, we describe techniques that provide practical and efficient protection of security sensitive code components in legacy binary code. Our technique dissects input binaries into multiple components which are further built into SGX enclave instances. We also leverage deliberately-designed binary editing techniques to retrofit the input binary code and preserve the original program semantics. Our tentative evaluations on hardening AES encryption and decryption procedures demonstrate the practicability and efficiency of the proposed technique.

Bianchi, Antonio, Gustafson, Eric, Fratantonio, Yanick, Kruegel, Christopher, Vigna, Giovanni.  2017.  Exploitation and Mitigation of Authentication Schemes Based on Device-Public Information. Proceedings of the 33rd Annual Computer Security Applications Conference. :16–27.

Today's mobile applications increasingly rely on communication with a remote backend service to perform many critical functions, including handling user-specific information. This implies that some form of authentication should be used to associate a user with their actions and data. Since schemes involving tedious account creation procedures can represent "friction" for users, many applications are moving toward alternative solutions, some of which, while increasing usability, sacrifice security. This paper focuses on a new trend of authentication schemes based on what we call "device-public" information, which consists of properties and data that any application running on a device can obtain. While these schemes are convenient to users, since they require little to no interaction, they are vulnerable by design, since all the needed information to authenticate a user is available to any app installed on the device. An attacker with a malicious app on a user's device could easily hijack the user's account, steal private information, send (and receive) messages on behalf of the user, or steal valuable virtual goods. To demonstrate how easily these vulnerabilities can be weaponized, we developed a generic exploitation technique that first mines all relevant data from a victim's phone, and then transfers and injects them into an attacker's phone to fool apps into granting access to the victim's account. Moreover, we developed a dynamic analysis detection system to automatically highlight problematic apps. Using our tool, we analyzed 1,000 popular applications and found that 41 of them, including the popular messaging apps WhatsApp and Viber, were vulnerable. Finally, our work proposes solutions to this issue, based on modifications to the Android API.

Buhren, Robert, Gueron, Shay, Nordholz, Jan, Seifert, Jean-Pierre, Vetter, Julian.  2017.  Fault Attacks on Encrypted General Purpose Compute Platforms. Proceedings of the Seventh ACM on Conference on Data and Application Security and Privacy. :197–204.

Adversaries with physical access to a target platform can perform cold boot or DMA attacks to extract sensitive data from the RAM. To prevent such attacks, hardware vendors announced respective processor extensions. AMD's extension SME will provide means to encrypt the RAM to protect security-relevant assets that reside there. The encryption will protect the user's content against passive eavesdropping. However, the level of protection it provides in scenarios that involve an adversary who cannot only read from RAM but also change content in RAM is less clear. This paper addresses the open research question whether encryption alone is a dependable protection mechanism in practice when considering an active adversary. To this end, we first build a software based memory encryption solution on a desktop system which mimics AMD's SME. Subsequently, we demonstrate a proof-of-concept fault attack on this system, by which we are able to extract the private RSA key of a GnuPG user. Our work suggests that transparent memory encryption is not enough to prevent active attacks.

Davidson, Drew, Chen, Yaohui, George, Franklin, Lu, Long, Jha, Somesh.  2017.  Secure Integration of Web Content and Applications on Commodity Mobile Operating Systems. Proceedings of the 2017 ACM on Asia Conference on Computer and Communications Security. :652–665.

A majority of today's mobile apps integrate web content of various kinds. Unfortunately, the interactions between app code and web content expose new attack vectors: a malicious app can subvert its embedded web content to steal user secrets; on the other hand, malicious web content can use the privileges of its embedding app to exfiltrate sensitive information such as the user's location and contacts. In this paper, we discuss security weaknesses of the interface between app code and web content through attacks, then introduce defenses that can be deployed without modifying the OS. Our defenses feature WIREframe, a service that securely embeds and renders external web content in Android apps, and in turn, prevents attacks between em- bedded web and host apps. WIREframe fully mediates the interface between app code and embedded web content. Un- like the existing web-embedding mechanisms, WIREframe allows both apps and embedded web content to define simple access policies to protect their own resources. These policies recognize fine-grained security principals, such as origins, and control all interactions between apps and the web. We also introduce WIRE (Web Isolation Rewriting Engine), an offline app rewriting tool that allows app users to inject WIREframe protections into existing apps. Our evaluation, based on 7166 popular apps and 20 specially selected apps, shows these techniques work on complex apps and incur acceptable end-to-end performance overhead.

Moon, Hyungon, Lee, Jinyong, Hwang, Dongil, Jung, Seonhwa, Seo, Jiwon, Paek, Yunheung.  2017.  Architectural Supports to Protect OS Kernels from Code-Injection Attacks and Their Applications. ACM Trans. Des. Autom. Electron. Syst.. 23:10:1–10:25.

The kernel code injection is a common behavior of kernel-compromising attacks where the attackers aim to gain their goals by manipulating an OS kernel. Several security mechanisms have been proposed to mitigate such threats, but they all suffer from non-negligible performance overhead. This article introduces a hardware reference monitor, called Kargos, which can detect the kernel code injection attacks with nearly zero performance cost. Kargos monitors the behaviors of an OS kernel from outside the CPU through the standard bus interconnect and debug interface available with most major microprocessors. By watching the execution traces and memory access events in the monitored target system, Kargos uncovers attempts to execute malicious code with the kernel privilege. On top of this, we also applied the architectural supports for Kargos to the detection of ROP attacks. KS-Stack is the hardware component that builds and maintains the shadow stacks using the existing supports to detect this ROP attacks. According to our experiments, Kargos detected all the kernel code injection attacks that we tested, yet just increasing the computational loads on the target CPU by less than 1% on average. The performance overhead of the KS-Stack was also less than 1%.

Huber, Manuel, Horsch, Julian, Wessel, Sascha.  2017.  Protecting Suspended Devices from Memory Attacks. Proceedings of the 10th European Workshop on Systems Security. :10:1–10:6.

Today's computing devices keep considerable amounts of sensitive data unencrypted in RAM. When stolen, lost or simply unattended, attackers are capable of accessing the data in RAM with ease. Valuable and possibly classified data falling into the wrongs hands can lead to severe consequences, for instance when disclosed or reused to log in to accounts or to make transactions. We present a lightweight and hardware-independent mechanism to protect confidential data on suspended Linux devices against physical attackers. Our mechanism rapidly encrypts the contents of RAM during suspension and thereby prevents attackers from retrieving confidential data from the device. Existing systems can easily be extended with our mechanism while fully preserving the usability for end users.

Hu, X., Tang, W., Liu, H., Zhang, D., Lian, S., He, Y..  2017.  Construction of bulk power grid security defense system under the background of AC/DC hybrid EHV transmission system and new energy. IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society. :5713–5719.

With the rapid development of bulk power grid under extra-high voltage (EHV) AC/DC hybrid power system and extensive access of distributed energy resources (DER), operation characteristics of power grid have become increasingly complicated. To cope with new severe challenges faced by safe operation of interconnected bulk power grids, an in-depth analysis of bulk power grid security defense system under the background of EHV and new energy resources was implemented from aspects of management and technology in this paper. Supported by big data and cloud computing, bulk power grid security defense system was divided into two parts: one is the prevention and control of operation risks. Power grid risks are eliminated and influence of random faults is reduced through measures such as network planning, power-cut scheme, risk pre-warning, equipment status monitoring, voltage control, frequency control and adjustment of operating mode. The other is the fault recovery control. By updating “three defense lines”, intelligent relay protection is used to deal with the challenges brought by EHV AC/DC hybrid grid and new energy resources. And then security defense system featured by passive defense is promoted to active type power grid security defense system.

Krupp, B., Jesenseky, D., Szampias, A..  2017.  SPEProxy: Enforcing fine grained security and privacy controls on unmodified mobile devices. 2017 IEEE 8th Annual Ubiquitous Computing, Electronics and Mobile Communication Conference (UEMCON). :520–526.

Mobile applications have grown from knowing basic personal information to knowing intimate details of consumer's lives. The explosion of knowledge that applications contain and share can be contributed to many factors. Mobile devices are equipped with advanced sensors including GPS and cameras, while storing large amounts of personal information including photos and contacts. With millions of applications available to install, personal data is at constant risk of being misused. While mobile operating systems provide basic security and privacy controls, they are insufficient, leaving the consumer unaware of how applications are using permissions that were granted. In this paper, we propose a solution that aims to provide consumers awareness of applications misusing data and policies that can protect their data. From this investigation we present SPEProxy. SPEProxy utilizes a knowledge based approach to provide consumer's an ability to understand how applications are using permissions beyond their stated intent. Additionally, SPEProxy provides an awareness of fine grained policies that would allow the user to protect their data. SPEProxy is device and mobile operating system agnostic, meaning it does not require a specific device or operating system nor modification to the operating system or applications. This approach allows consumers to utilize the solution without requiring a high degree of technical expertise. We evaluated SPEProxy across 817 of the most popular applications in the iOS App Store and Google Play. In our evaluation, SPEProxy was highly effective across 86.55% applications where several well known applications exhibited misusing granted permissions.

Falk, E., Repcek, S., Fiz, B., Hommes, S., State, R., Sasnauskas, R..  2017.  VSOC - A Virtual Security Operating Center. GLOBECOM 2017 - 2017 IEEE Global Communications Conference. :1–6.

Security in virtualised environments is becoming increasingly important for institutions, not only for a firm's own on-site servers and network but also for data and sites that are hosted in the cloud. Today, security is either handled globally by the cloud provider, or each customer needs to invest in its own security infrastructure. This paper proposes a Virtual Security Operation Center (VSOC) that allows to collect, analyse and visualize security related data from multiple sources. For instance, a user can forward log data from its firewalls, applications and routers in order to check for anomalies and other suspicious activities. The security analytics provided by the VSOC are comparable to those of commercial security incident and event management (SIEM) solutions, but are deployed as a cloud-based solution with the additional benefit of using big data processing tools to handle large volumes of data. This allows us to detect more complex attacks that cannot be detected with todays signature-based (i.e. rules) SIEM solutions.

Yang, Wei, Xiao, Xusheng, Pandita, Rahul, Enck, William, Xie, Tao.  2014.  Improving Mobile Application Security via Bridging User Expectations and Application Behaviors. Proceedings of the 2014 Symposium and Bootcamp on the Science of Security. :32:1–32:2.

To keep malware out of mobile application markets, existing techniques analyze the security aspects of application behaviors and summarize patterns of these security aspects to determine what applications do. However, user expectations (reflected via user perception in combination with user judgment) are often not incorporated into such analysis to determine whether application behaviors are within user expectations. This poster presents our recent work on bridging the semantic gap between user perceptions of the application behaviors and the actual application behaviors.

Yu, Xianqing, Ning, Peng, Vouk, Mladen A..  2014.  Securing Hadoop in Cloud. Proceedings of the 2014 Symposium and Bootcamp on the Science of Security. :26:1–26:2.

Hadoop is a map-reduce implementation that rapidly processes data in parallel. Cloud provides reliability, flexibility, scalability, elasticity and cost saving to customers. Moving Hadoop into Cloud can be beneficial to Hadoop users. However, Hadoop has two vulnerabilities that can dramatically impact its security in a Cloud. The vulnerabilities are its overloaded authentication key, and the lack of fine-grained access control at the data access level. We propose and develop a security enhancement for Cloud-based Hadoop.

Huang, Jingwei, Nicol, David M..  2014.  Evidence-based Trust Reasoning. Proceedings of the 2014 Symposium and Bootcamp on the Science of Security. :17:1–17:2.

Trust is a necessary component in cybersecurity. It is a common task for a system to make a decision about whether or not to trust the credential of an entity from another domain, issued by a third party. Generally, in the cyberspace, connected and interacting systems largely rely on each other with respect to security, privacy, and performance. In their interactions, one entity or system needs to trust others, and this "trust" frequently becomes a vulnerability of that system. Aiming at mitigating the vulnerability, we are developing a computational theory of trust, as a part of our efforts towards Science of Security. Previously, we developed a formal-semantics-based calculus of trust [3, 2], in which trust can be calculated based on a trustor's direct observation on the performance of the trustee, or based on a trust network. In this paper, we construct a framework for making trust reasoning based on the observed evidence. We take privacy in cloud computing as a driving application case [5].