Abstract : The majority of today's web-based applications are based on back-end databases to process and store business information. Containing valuable business information, these systems are highly interesting to attackers and special care needs to be taken to prevent them from malicious accesses. In this paper, we propose (RBAC + ), an extension of the NIST RBAC (Role-Based Access Control) standard with the notions of application, application profile and sub-application session to distinguish end users that execute the same application, providing them by only the needed roles and continuously monitoring them throughout a whole session. It is based on business application logic rather than primitive reads and writes to enhance the ability of detecting malicious transactions. Hence, attacks caused by malicious transactions can be detected and canceled timely before they succeed.