Design and development of Anti-XSS proxy

Cross-Site Scripting (XSS) vulnerability allows an attacker to inject arbitrary JavaScript code that can be executed in the victim´s browser and cause security breaches. The discovery of XSS is still widespread among today´s web applications. As a result, there is a need to improve existing solutions or develop novel attack detection techniques. This paper proposes a proxy-level design and development of XSS attack detection approach (Anti-XSS) based on Kullback-Leibler Divergence (KLD) measure. The proposed approach has been applied for a number of open-source PHP web applications containing XSS vulnerabilities. The initial results show that the approach can effectively detect XSS attacks while displaying a low false positive rate depending on the choice of threshold values of KLD.