Anti-virtual machines and emulations

Virtual Machines are important infrastructural tools for malware analysis. They provide safe yet accurate way of evaluating real life behavior and impact of any executable code, thus providing a better understanding of obfuscated or non conventional portions of code within a binary file. Many virtual machines, such as VMware, Qemu, VirtualBox and SandBoxes, are available and are widely adopted by malware researchers and analysts. Moreover, many antivirus scanners have their own implementation of emulators to achieve comparable results by running malicious code within a controlled environment in order to decrypt obfuscated code. Virus writers have always responded to these technologies. Most malware today uses anti-debug techniques to counter analysis and evade antivirus detection. Lately, malware like Zeus/SpyEye and associated families such as Smoaler, Dromedan, Kazy, Yakes, and other malware such as Spyrat or W32.Pilleuz, have deployed techniques to disrupt the use of virtual machines and emulators. These malware families are able to implement different variations of disruption techniques within single samples or within related groups of malware before propagation. This paper will present a study of these anti-emulation and anti-virtual machine techniques.     

Anodic behaviour of α-PbO2 substrates containing different percentages of lower lead oxides

A study has been made of the anodic behavior of lead oxide deposits containing 92, 80 and 60%α-PbO₂. The non-porous deposits were prepared by electrodeposition from a plumbite bath containing different proportions of 30% formaldehyde solution, acting as a reductant in the cases of 80 and 60%α-PbO₂. Measurements of the steady-state oxygen evolution reaction under constant surface conditions of the electrodes, were carried out galvanostatically within the current-density range 30–190μAcm^?2. The oxygen overpotential values were found to increase with increasing the amount of superficially formedβ-PbO₂ during anodization in sulphuric acid solution. In the proposed mechanism for the o.e.r, the rate determining step is an electron-transfer reaction. Tafel slopes having values of 220±10 mV dec^?1 were obtained. Possible interpretation of these higher slopes is given which is based on the dual barrier model. Potential-time decay curves reveal a retarded oxygen diffusion process.     

Adsorption Effect of Cationic Surfactants on Corrosion Inhibition of Steel

Corrosion behaviour of steel in acid solutions was followed in presence of cationic micells of Cetyltrimethylammonium bromide (CTABr), n-tetradecyl-N,N,N-trimethylammonium bromide (TDTABr), n-dodecyltrimethylammonium bromide (DDTABr) and n-decyltrimethylammonium bromide (DTABr) using gasometry and potentiodynamic techniques. Plots of adsorption isotherms produce S- shaped curves. Surfactants were found to act as corrosion inhibitors of mixed - type, i.e., affecting the dissolution of the metal and the cathodic reaction of hydrogen evolution. Inhibitive effect of the surfactants has been shown to increase with the alkyl chain length and at concentrations above their critical micelle concentration (cmc). Corrosion kinetic empirical equation describing the relationship between the surfactants structure and their activity is introduced. The number of active sites on the metal occupied by the surfactant molecule, binding constant and change in free energy of adsorption are calculated following Temkin adsorption isotherms. All results obtained are compared to the kinetic-thermodynamic model to certify its applicability. The mode of adsorption of the surfactant molecules according to their structure is also discussed.     

On the modulation of scattered light in the measurement of a new parameter of transparent polymers

Light radiation energy, in the form of a polarised monochromatic light vector, when passing through a plate of a transparent polymer, undergoes a media-characteristic dependent modulation. The arrangement of the polymeric chain axes affects the propagating light vector even in the case of a load-free subject. Some unloaded transparent polymers cause modulations that differ as the polarised monochromatic primary beam moves deeper in the material. This optical phenomenon is explored in selected photoelastic materials. Problems associated with the practical implementation of these materials in scattered photoelasticity are pointed out.     

Error assessment of the estimated coefficients obtained in system identification technique

System identification technique plays an important role in many electrical devices. In this technique, an adaptive filter models the unknown system with a finite impulse response or an infinite inverse response filter. This paper concentrates on the system identification technique based on the least squares criterion and evaluates the relationship between each estimated coefficient (obtained by the adaptive filter) and its corresponding coefficient in the unknown system. By logically classifying the variables, the amount of error between these two corresponding coefficients is evaluated and precisely expressed based on the autocorrelation lags of the input signal of the system and the coefficients of the unknown system. Also, the computed error is simplified for two particular cases in which the input signal of the system is an ideal zero-mean white Gaussian noise or a windowed (short-time) zero-mean white Gaussian noise. Experimental results provided in the simulation part verify the arithmetic expressions presented in the paper.     

Vector wave expansion method for leaky modes of microstructured optical fibers

A new method for calculating the confinement loss of leaky modes in arbitrary microstructured optical fibers is presented. The full vector algorithm is based on a polar coordinate Fourier decomposition method with adjustable boundary conditions, capable of accurately determining the outward radiating fields of the waveguide. Example waveguides with circular and elliptical hole shapes and their leaky mode solutions are presented and discussed.