Shining Light On Shadow Stacks

Control-Flow Hijacking attacks are the dominant attack vector against C/C++ programs. Control-Flow Integrity (CFI) solutions mitigate these attacks on the forward edge,i.e., indirect calls through function pointers and virtual calls. Protecting the backward edge is left to stack canaries, which are easily bypassed through information leaks. Shadow Stacks are a fully precise mechanism for protecting backwards edges, and should be deployed with CFI mitigations. We present a comprehensive analysis of all possible shadow stack mechanisms along three axes: performance, compatibility, and security. For performance comparisons we use SPEC CPU2006, while security and compatibility are qualitatively analyzed. Based on our study, we renew calls for a shadow stack design that leverages a dedicated register, resulting in low performance overhead, and minimal memory overhead, but sacrifices compatibility. We present case studies of our implementation of such a design, Shadesmar, on Phoronix and Apache to demonstrate the feasibility of dedicating a general purpose register to a security monitor on modern architectures, and the deployability of Shadesmar. Our comprehensive analysis, including detailed case studies for our novel design, allows compiler designers and practitioners to select the correct shadow stack design for different usage scenarios.Comment: To Appear in IEEE Security and Privacy 201

Why Principal Positive Leadership Is Important: It’s Mediating Effect on the Relation between the School Context and Student Academic Achievement

“Deficit remediation” as an educational governance paradigm has given rise to many problems, whereas principal positive leadership under the “strengths development” paradigm has the potential to give new impetus to school development. Based on large-scale survey data within a provincial region, this study investigates how the school context and principal positive leadership impact student academic achievement using structural equation models. Research findings show that principal positive leadership as a structural latent variable has positive impacts on student academic performance and significantly mediates the effects of the school context on student academic results; and that the patterns of the impacts of principal positive leadership differ according to the variations of the school’s autonomy in operation

National Essential Medicines List and policy practice: A case study of China’s health care reform

BACKGROUND: In 2009, China implemented the national essential medicines system by enacting the National Essential Medicines List 2009. According to the policy of this system, primary health care institutions can only stock and use essential medicines on the prescribed List. Meanwhile, each province can choose to make its own list of supplemented medicines. The goal of the study is to provide suggestions for emerging problems and identify future policy-making trends. METHODS: In this study, we statistically analyzed the National Essential Medicines List 2009 and lists of supplemented medicines of all 29 provinces. We also examined the rationality of such medicines based on the DELPHI method and literature review, after which we studied the provincial supplements in relation to the national essential medicines system. RESULTS: We demonstrated that the National Essential Medicines List 2009 provides a comprehensive coverage of diseases as well as reasonable varieties of drugs for their treatment. The average number of supplemented medicines in 29 provinces is 207, with each medicine included in 2.9 provincial lists on average. Only 2.6% supplemented medicines are included by more than half of the provinces (>15), indicating great regional variance. Among the 32 most frequently supplemented medicines, only 18 meet the selection principles, including two with strict usage restrictions. CONCLUSION: The structure and selection of the National Essential Medicines List 2009 are relatively reasonable. The main problems, however, include the excessive and non-scientific selection of medicines on the supplemented medicines list. The function of the provincial lists of supplemented medicines has not been achieved, which has influenced the effectiveness of the national essential medicines system in China

Clustering Scatter Plots Using Data Depth Measures.

Clustering is rapidly becoming a powerful data mining technique, and has been broadly applied to many domains such as bioinformatics and text mining. However, the existing methods can only deal with a data matrix of scalars. In this paper, we introduce a hierarchical clustering procedure that can handle a data matrix of scatter plots. To more accurately reflect the nature of data, we introduce a dissimilarity statistic based on "data depth" to measure the discrepancy between two bivariate distributions without oversimplifying the nature of the underlying pattern. We then combine hypothesis testing with hierarchical clustering to simultaneously cluster the rows and columns of the data matrix of scatter plots. We also propose novel painting metrics and construct heat maps to allow visualization of the clusters. We demonstrate the utility and power of our new clustering method through simulation studies and application to a microbe-host-interaction study

Characteristics of Hospitals That Adopt Hospital Information Systems in Mongolia And Its Impact on Patient Safety and Quality of Care

Objectives: Our objective was to determine the relationship between the adoption of hospital information system (HIS) in Mongolian tertiary and secondary care hospitals and the hospital’s organizational & geographical characteristics, its impact on patient safety & quality of healthcare. Methods: This wasa cross sectional study involving the executive directors and 39 quality managersat 39 hospitals. Data werecollected using questionnaire to determine the adoption rate of HIS and their hospital’s organizational & geographical characteristics. Results: The adoption of HIS signifi cantly affected by hospital size, ownership type, health maintenance organization penetration, and hospital location (urban versus rural). The adoption of HIS was found to partially impactpatient safety and quality of healthcare outcomes. Conclusion: In terms of theoretical implications, this study confi rms that hospital organizational & geographical characteristics (structure) impact the adoption of HIS (process) which in turn affects healthcare outcomes (outcome). These fi nding validate Avedis Donabedian’s “Structure-Process-Outcome” model. The present fi ndings also confi rm that hospitals with these structural attributes adopted more technologies

MODELING RETURN PERIODS OF TROPICAL CYCLONES IN THE VICINITY OF HAWAI’I

M.S