A lightweight implementation of trusted domain enforcement for secure embedded web server

Deployment of open source software for embedded system is increasing while ubiquitous devices have become widely used. System designer need to cope with malicious input which is made from exposed vulnerability. Lightweight verification and sandbox approach is effective for embedded system, because embedded system is specified, has less generic purpose than PC and servers. In this paper we apply TDE (Trusted Domain Enforcement) for embedded Linux 2.6 series in order to achieve dynamic sandboxing. TDE is a concept showed in TCSEC (Trusted Computer System Evaluation Criteria) for input validation and sandbox for protecting system. TDE is a kind of extension of TE (Type Enforcement) for dynamic sandboxing although its implementation could be reasonably simple. Our system is based on LIDS (Linux Intrusion System) for Linux 2.4 series. We implement our system as small kernel patch. We also discuss the application of our method for embedded web server. We have coped with thttpd in implementing our TDE system.