Data processing for anomaly detection in web-based applications

Web applications are popular attack targets. Misuse detection systems use signature databases to detect known attacks. However, it is difficult to keep the database up to date with the rate of discovery of vulnerabilities. They also cannot detect zero-day attacks. By contrast, anomaly detection systems learn the normal behavior of the system and monitor its activity to detect any deviations from the normal. Any such deviations are flagged as anomalous. This thesis presents an anomaly detection system for web-based applications. The anomaly detection system monitors the attribute value pairs of successful HTTP requests received by webserver applications and automatically creates parameter profiles. It then uses these profiles to detect anomalies in the HTTP requests. Customized profiles help reduce the number of false positives. Automatic learning ensures that the system can be used with different kinds of web application environments, without the necessity for manual configuration. The results of the detection are also visualized, which enable the system administrator to quickly understand the state of the system and respond accordingly.Keywords: anomaly, anomaly detection, web application, security, computer science, computer security, compute

Dispiro-1,2,4-trioxane Analogues of a Prototype Dispiro-1,2,4-trioxolane: Mechanistic Comparators for Artemisinin in the Context of Reaction Pathways with Iron(II)

Single electron reduction of the 1,2,4-trioxane heterocycle of artemisinin (1) forms primary and secondary carbon-centered radicals. The complex structure of 1 does not lend itself to a satisfactory dissection of the electronic and steric effects that influence the formation and subsequent reaction of these carbon-centered free radicals. To help demarcate these effects, we characterized the reactions of achiral dispiro-1,2,4-trioxolane 4 and dispiro-1,2,4-trioxanes 5−7 with ferrous bromide and 4-oxo-TEMPO. Our results suggest a small preference for attack of Fe(II) on the nonketal peroxide oxygen atom of 1. For 4, but not for 5 and 6, there was a strong preference for attack of Fe(II) on the less hindered peroxide bond oxygen atom. The steric hindrance afforded by a spiroadamantane in a five-membered trioxolane is evidently much greater than that for a corresponding six-membered trioxane. Unlike 1, 5−7 fragment by entropically favored β-scission pathways forming relatively stable α-oxa carbon-centered radicals. These data suggest that formation of either primary or secondary carbon-centered radicals is a necessary but insufficient criterion for antimalarial activity of 1 and synthetic peroxides

Variation of the Si II features in the chemically peculiar star -HD 115735

Abstract. The chemically peculiar star HD 115735 (= HR 5023 = 21 CVn) was observed with the 2.34 meter Vainu Bappu Telescope at Kavalur during the period of January 1999 to April 2000. A total of 47 spectrograms were obtained in the wavelength region of 3900Å to 4400Å at a resolution of 0.65 A per pixel. The equivalent widths of Si II features at 4077, 4128, 4131Å have been found to be varying with a period of 0.88 ± 0.02 day, the amplitudes being about 0.1Å. This is the first report of spectroscopic variations of these features in this star