Biblio

The Extensible Markup Language (XML) is a complex language, and consequently, XML-based protocols are susceptible to entire classes of implicit and explicit security problems. Message formats in XML-based protocols are usually specified in XML Schema, and as a first-line defense, schema validation should reject malformed input. However, extension points in most protocol specifications break validation. Extension points are wildcards and considered best practice for loose composition, but they also enable an attacker to add unchecked content in a document, e.g., for a signature wrapping attack. This paper introduces datatyped XML visibly pushdown automata (dXVPAs) as language representation for mixed-content XML and presents an incremental learner that infers a dXVPA from example documents. The learner generalizes XML types and datatypes in terms of automaton states and transitions, and an inferred dXVPA converges to a good-enough approximation of the true language. The automaton is free from extension points and capable of stream validation, e.g., as an anomaly detector for XML-based protocols. For dealing with adversarial training data, two scenarios of poisoning are considered: a poisoning attack is either uncovered at a later time or remains hidden. Unlearning can therefore remove an identified poisoning attack from a dXVPA, and sanitization trims low-frequent states and transitions to get rid of hidden attacks. All algorithms have been evaluated in four scenarios, including a web service implemented in Apache Axis2 and Apache Rampart, where attacks have been simulated. In all scenarios, the learned automaton had zero false positives and outperformed traditional schema validation.

Web application security has become crucially vital these days. Earlier "default allow" model was used to secure web applications but it was unable to secure web applications against plethora of attacks [1]. In contrast, more restricted security to the web applications is provided by default deny model which at first, builds a model for the particular application and then permits merely those requests that conform to that model while ignoring everything else. Besides this, a novel and effective methodology is followed that allows to analyze the validity of application requests and further results in the generation of semi structured XML cases for the web applications. Furthermore, mature and resilient XML cases are generated by employing learning techniques. This system will further be gauged by examining that XML file containing cases are in correct accordance with the XML format or not. Moreover, the distinction between malicious and non-malicious traffic is carried out carefully. Results have proved its efficacy of rule generation employing access traffic log of cross site scripting (XSS), SQL injection, HTTP Request Splitting, HTTP response splitting and Buffer overflow attacks.