A Security Sensitive Function Mining Approach Based on Precondition Pattern Analysis

Security-sensitive functions are the basis for building a taint-style vulnerability model.Current approaches for extracting security-sensitive functions either don’t analyze data flow accurately,or not conducting pattern analyzing of conditions,resulting in higher false positive rate or false negative rate,which increased manual confirmation workload.In this paper,we propose a security sensitive function mining approach based on preconditon pattern analyzing.Firstly,we propose an enhanced system dependency graph analysis algorithm for precisely extracting the conditional statements which check the function parameters and conducting statistical analysis of the conditional statements for selecting candidate security sensitive functions of the target program.Then we adopt a precondition pattern mining method based on conditional statements nomalizing and clustering.Functions with fixed precondition patterns are regarded as security-sensitive functions.The experimental results on four popular open source codebases of different scales show that the approach proposed is effective in reducing the false positive rate and false negative rate for detecting security sensitive functions.

Preparation of silicon-doped ferrihydrite for adsorption of lead and cadmium:Property and mechanism

In this study,Si-doped ferrihydrite(Si-Fh) was successfully synthesized by a simple coprecipitation method for removal of heavy metals in water.Subsequently,the physicochemical properties of Si-Fh before and after adsorption were further studied using several techniques.The Si-Fh exhibited good adsorption capacity for heavy metal ions such as Pb(II) and Cd(II).The maximum adsorption capacities of lead and cadmium are respectively 105.807,37.986 mg/g.The distribution coefficients of the materials for Pb(II) and Cd(II) also showed a great affinity(under optimal conditions).Moreover,it was found that the adsorption fit well with the Freundlich isotherm and pseudo-second-order kinetic model which means this was a chemical adsorption process.It can be conducted from both characterization and model results that adsorption of Pb(II) and Cd(II) was mainly through the complexation interaction of abundance oxygen functional groups on the surface of Si-Fh.Overall,the Si-Fh adsorbents with many superiorities have potential for future applications in the removal of Pb(II) and Cd(II) from wastewater.

Synthesis of Mg(Ⅱ)doped ferrihydrite-humic acid coprecipitation and its Pb(Ⅱ)/Cd(Ⅱ)ion sorption mechanism

A magnesium doped ferrihydrite-humic acid coprecipitation(Mg-doped Fh-HA)was synthesized by coprecipitation method.The removal of heavy metals such as Pb(Ⅱ)and Cd(Ⅱ)was assessed.The isotherms and kinetic studies indicated that the Mg-doped Fh-HA exhibited a remarkable Pb(Ⅱ)and Cd(Ⅱ)sorption capacity(maximum 120.43 mg/g and 27.7 mg/g,respectively.)in aqueous solution.The sorption of Pb(Ⅱ)and Cd(Ⅱ)onto best fitted pseudo-second-order kinetic equation and Langmuir model.The adsorption mechanism of Mg-doped Fh-HA on Pb(Ⅱ)and Cd(Ⅱ)involves surface adsorption,surface complexation and surface functional groups(such as carboxyl group,hydroxyl group).In addition,ionexchange and precipitation cannot be ignored.The Mg-doped Fh-HA is a low-cost and high-performance adsorption material and has a wide range of application prospects.