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

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

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

M.S

Willingness to Pay for Social Health Insurance among Informal Sector Workers in Wuhan, China: a Contingent Valuation Study

Background: Most of the about 140 million informal sector workers in urban China do not have health insurance. A 1998 central government policy leaves it to the discretion of municipal governments to offer informal sector workers in cities voluntary participation in a social health insurance for formal sector workers, the so-called 'basic health insurance' (BHI). Methods: We used the contingent valuation method to assess the maximum willingness to pay (WTP) for BHI among informal sector workers, including unregistered rural-to-urban migrants, in Wuhan City, China. We selected respondents in a two-stage self-weighted cluster sampling scheme. Results: On average, informal sector workers were willing to pay substantial amounts for BHI (30 Renminbi (RMB), 95% confidence interval (CI) 27-33) as well as substantial proportions of their incomes (4.6%, 95% CI 4.1-5.1%). Average WTP increased significantly when any one of the copayments of the BHI was removed in the valuation: to 51 RMB (95% CI 46-56) without reimbursement ceiling; to 43 RMB (95% CI 37-49) without deductible; and to 47 RMB (95% CI 40-54) without coinsurance. WTP was higher than estimates of the cost of BHI based on past health expenditure or on premium contributions of formal sector workers. Predicted coverage with BHI declined steeply with the premium contribution at low contribution levels. When we applied equity weighting in the aggregation of individual WTP values in order to adjust for inequity in the distribution of income, mean WTP for BHI increased with inequality aversion over a plausible range of the aversion parameter. Holding other factors constant in multiple regression analysis, for a 1% increase in income WTP for BHI with different copayments increased by 0.434-0.499% (all p < 0.0001), and for a 1% increase in past health care expenditure WTP increased by 0.076-0.148% (all p < 0.0004). Being male, a migrant, or without permanent employment significantly decreased WTP for BHI. Education was not a significant determinant of WTP for BHI. Conclusion: Our results suggest that Chinese municipal governments should allow informal sector workers to participate in the BHI. From a normative perspective, BHI for informal sector workers is likely to increase social welfare because average WTP for BHI is significantly higher than estimates of the average cost of BHI. We further find that informal sector workers do not value the BHI as a mechanism to recover the relatively frequent but small financial losses associated with common illnesses, but because it protects against the rare but large financial losses associated with catastrophic care. From a behavioural perspective, our results predict that at a price equal to the average premium contribution of formal sector workers 35% of informal sector workers will enrol in the BHI. Subsidies and changes in insurance attributes (e.g. including catastrophic care and portability) should be effective in increasing BHI coverage. In addition, coverage should expand with rising incomes among informal sector workers in China. Finally, adverse selection will be unlikely to be a large problem, if the BHI is offered to informal sector workers

Automation System Vibration Analysis Taking Environmental Factors into Consideration

This paper aims to investigate the vibration behavior of a propulsion system subjected to hull deformations ina two dimension circumstance. As known that large scale ships have great developments in recent years which could cause much severer conditions among the interaction between the propulsion system and ship hull. Excited forces from thesea waves could make the ship hull deformed which further cause drastic vibrations of the shaft system. As a result, the malfunctions of shaft propulsion system are potential existed as the vibrations of the shaft always exceed its maximum allowable values.This paper establishes a simplified model of the large ship propulsion-hull system to analyze the vibration behavior of the ship propulsion system subjected to the ship hull deformations. The hull deformations were obtained as the excited forces under different sea conditions. Then base on the simplified 2D model, the effects of propeller, supports stiffness, the location of hull excitations, the amplitude of excitations are discussed.