Pyrena: Closing the semantic gap for access control in web-based content management systems

Open Access
Bergstein, Adam
Graduate Program:
Computer Science and Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 28, 2014
Committee Members:
  • Trent Ray Jaeger, Thesis Advisor/Co-Advisor
  • Dr Patrick Mc Daniel, Thesis Advisor/Co-Advisor
  • content management systems
  • access control
  • security
Large organizations that wish to publish content to the Web are increasingly turning to Content Man- agement Systems (CMSs). A CMS allows a large set of members within the organization to author and publish content within their domains of expertise without having to consider the overarching organiza- tion or presentation of the content. Unfortunately, modern CMSs tend to be implemented as add-ons to webservers, leading to a semantic gap between the CMS and some types of content stored on the host machine. In this paper, we demonstrate how this semantic gap can leave sensitive files world-accessible in the widely used Drupal CMS. As a solution, we introduce Pyrena, a reference monitor that mediates file system access to resources owned by the CMS. We show that Pyrena maintains not only the well-known security properties of a reference monitor, but also does not break existing third-party access control plugins, or common use cases of the Drupal CMS.