Evading Classifiers by Morphing in the Dark

Learning-based systems have been shown to be vulnerable to evasion through adversarial data manipulation. These attacks have been studied under assumptions that the adversary has certain knowledge of either the target model internals, its training dataset or at least classification scores it assigns to input samples. In this paper, we investigate a much more constrained and realistic attack scenario wherein the target classifier is minimally exposed to the adversary, revealing on its final classification decision (e.g., reject or accept an input sample). Moreover, the adversary can only manipulate malicious samples using a blackbox morpher. That is, the adversary has to evade the target classifier by morphing malicious samples "in the dark". We present a scoring mechanism that can assign a real-value score which reflects evasion progress to each sample based on the limited information available. Leveraging on such scoring mechanism, we propose an evasion method -- EvadeHC -- and evaluate it against two PDF malware detectors, namely PDFRate and Hidost. The experimental evaluation demonstrates that the proposed evasion attacks are effective, attaining $100\%$ evasion rate on the evaluation dataset. Interestingly, EvadeHC outperforms the known classifier evasion technique that operates based on classification scores output by the classifiers. Although our evaluations are conducted on PDF malware classifier, the proposed approaches are domain-agnostic and is of wider application to other learning-based systems

Value of high-sensitivity C-reactive protein assays in predicting atrial fibrillation recurrence: a systematic review and meta-analysis

Objectives: We performed a systematic review and meta-analysis of studies on high-sensitivity C-reactive protein (hs-CRP) assays to see whether these tests are predictive of atrial fibrillation (AF) recurrence after cardioversion. Design: Systematic review and meta-analysis. Data sources PubMed, EMBASE and Cochrane databases as well as a hand search of the reference lists in the retrieved articles from inception to December 2013. Study eligibility criteria This review selected observational studies in which the measurements of serum CRP were used to predict AF recurrence. An hs-CRP assay was defined as any CRP test capable of measuring serum CRP to below 0.6 mg/dL. Primary and secondary outcome measures We summarised test performance characteristics with the use of forest plots, hierarchical summary receiver operating characteristic curves and bivariate random effects models. Meta-regression analysis was performed to explore the source of heterogeneity. Results: We included nine qualifying studies comprising a total of 347 patients with AF recurrence and 335 controls. A CRP level higher than the optimal cut-off point was an independent predictor of AF recurrence after cardioversion (summary adjusted OR: 3.33; 95% CI 2.10 to 5.28). The estimated pooled sensitivity and specificity for hs-CRP was 71.0% (95% CI 63% to 78%) and 72.0% (61% to 81%), respectively. Most studies used a CRP cut-off point of 1.9 mg/L to predict long-term AF recurrence (77% sensitivity, 65% specificity), and 3 mg/L to predict short-term AF recurrence (73% sensitivity, 71% specificity). Conclusions: hs-CRP assays are moderately accurate in predicting AF recurrence after successful cardioversion

SOFTWARE-AS-A-SERVICE (SAAS) INNOVATION IN THE CONTEXT OF SOFTWARE INDUSTRY: A RESOURCE ORCHESTRATION PERSPECTIVE

Cloud computing brings a paradigm shift in the software industry and changes the business model of software vendors (SV). Software as a service (SaaS), the most popular form of cloud computing, has been recognized as the fundamental change in the delivery, utilization, and management of software. While the transformation to SaaS requires changes within the organization, SVs must actively take action to attract customers to accept the SaaS business model, the so-called pull strategy. Drawing on the resource orchestration view, we propose that the antecedents (i.e., structuring cloud resources, developing service bundling capability, and leveraging cloud ecosystem) are related to the likelihood of an innovative SaaS, which, in turn, is associated with SaaS attractiveness to users. Our proposed research framework provides a guideline for SV to attract and persuade customers to adopt SaaS solutions actively

Mixed Fault Tolerance Protocols with Trusted Execution Environment

Blockchain systems are designed, built and operated in the presence of failures. There are two dominant failure models, namely crash fault and Byzantine fault. Byzantine fault tolerance (BFT) protocols offer stronger security guarantees, and thus are widely used in blockchain systems. However, their security guarantees come at a dear cost to their performance and scalability. Several works have improved BFT protocols, and Trusted Execution Environment (TEE) has been shown to be an effective solution. However, existing such works typically assume that each participating node is equipped with TEE. For blockchain systems wherein participants typically have different hardware configurations, i.e., some nodes feature TEE while others do not, existing TEE-based BFT protocols are not applicable. This work studies the setting wherein not all participating nodes feature TEE, under which we propose a new fault model called mixed fault. We explore a new approach to designing efficient distributed fault-tolerant protocols under the mixed fault model. In general, mixed fault tolerance (MFT) protocols assume a network of $n$ nodes, among which up to $f = \frac{n-2}{3}$ can be subject to mixed faults. We identify two key principles for designing efficient MFT protocols, namely, (i) prioritizing non-equivocating nodes in leading the protocol, and (ii) advocating the use of public-key cryptographic primitives that allow authenticated messages to be aggregated. We showcase these design principles by prescribing an MFT protocol, namely MRaft. We implemented a prototype of MRaft using Intel SGX, integrated it into the CCF blockchain framework, conducted experiments, and showed that MFT protocols can obtain the same security guarantees as their BFT counterparts while still providing better performance (both transaction throughput and latency) and scalability.Comment: 12 pages, 3 figure

Carbon Dioxide Capture Performance of Mesostructured Adsorbent Impregnated with Polyethylenimine

This study aims to investigate the CO2 uptake performance of mesostructured adsorbents, such as Mobil Composition of Matter No. 41 (MCM-41), Santa Barbara Amorphous-15 (SBA-15), and multi-walled carbon nanotubes (MWNTs), modified with polyethylenimine (PEI). Mesoporous materials are loaded with 50 wt.% PEI using a wet impregnation method. CO2 kinetic experiments of the PEI-modified adsorbents are conducted by a thermogravimetric method. The results reveal that the CO2 adsorption capacities of the PEI/MCM-41, PEI/SBA-15, and PEI/MWNTs composites are 2.02, 3.06, and 2.93 mmol/g, respectively, under 15% CO2 flow at 348 K. The lower CO2 adsorption capacity of PEI/MCM-41 (2.02 mmol/g) is attributed to its poor porosity. The PEI/MWNTs composite has the fastest CO2 adsorption and desorption kinetics at the same temperature, compared to other PEI-modified adsorbents. These results suggest that MWNTs might play a significant “separator” role in effectively dispersing the PEI molecular chains on the mesostructured adsorbent

Investigation of Cycling Performance in a Solid-State Fluoride-Ion Battery Based on Copper Fluoride Electrodes

This study investigates the performance and cycling fading of a solid-state fluoride-ion battery (FIB) based on the CuF2 electrode. The cathode and solid electrolyte of CuF2 composite and La0.9Ba0.1F2.9 are prepared by ball-milling. Meanwhile, the anode materials are used as Sn and Pb. All FIB cells with sandwich structures are fabricated by compressing under a pressure of 4.5 tons/cm2. Electrochemical measurements of discharge/charge are performed at 423 K and under 40 μA/cm2. The resultant cycling stability of the cell with the Pb anode is higher than that of the cell with the Sn anode. Concerning the cell with Pb anode, the first and tenth discharge capacities of 150 and 90 mAh/g are obtained. X-ray photoelectron analysis demonstrates that the cycling fading of the cell with the Sn (or Pb) anode may be attributed to the irreversible formation of materials (e.g., SnF4 or PbF4) during the electrochemical reaction

Directed diffraction without negative refraction

Using the FDTD method, we investigate the electromagnetic propagation in two-dimensional photonic crystals, formed by parallel air cylinders in a dielectric medium. The corresponding frequency band structure is computed using the standard plane-wave expansion method. It is shown that within partial bandgaps, waves tend to bend away from the forbidden directions. This phenomenon perhaps need not be explained in terms of negative refraction or `superlensing' behavior, contrast to what has been conjectured.Comment: 3 pages, 4 figure