Towards an Automatic Analysis of Web Service Security

The original publication is available at www.springerlink.comInternational audienceWeb services send and receive messages in XML syntax with some parts hashed, encrypted or signed, according to the WS-Security standard. We have introduced a model to formally describe the protocols that underly these services, their security properties and the rewriting attacks they might be subject to. Unlike other protocol models (in symbolic analysis) ours can handle non-deterministic receive/send actions and unordered sequence of XML nodes. Then to detect the attacks we have to consider the services as combining multiset operators and cryptographic ones and we have to solve specific satisfiability problems in the combined theory. By an extension of the combination techniques we obtain a decision procedure for insecurity of Web services with messages built using encryption, signature, and other cryptographic primitives. This combination technique allows one to decide insecurity in a modular way by reducing the associated constraint solving problems to problems in simpler theories.Nous introduisons un modèle abstrait des services web qui permet d'exprimer les attaques par réécriture. Nous proposons un algorithme pour détecter ce type de vulnérabilité