A Logic for Secure Stratified Systems and its Application to Containerized Systems
Hagen Lauer, Amin Sakzad, Carsten Rudolph, Surya Nepal · 2019
We present the design and verification of a secure integrity measurement system for containerized systems. Containerization of applications allows fine-graded deployment and management of services and dependencies but also needs fine-graded security mechanisms. In this paper we provide formal abstractions for containerized systems by introducing LS^3, a formal model and logic with sub-domain constructs to represent stratified systems and their interactions. Using our formal model, we prove that the widely used Trusted Computing Group (TCG) based Integrity Measurement Architecture (IMA) securely extends trust measurements from boot to applications. However, IMA is not designed to make domain specific trust measurements and is consequently incapable of creating domain specific integrity reports. Current research aims to improve either trust measurement performance or comprehensiveness but does not improve the measurement function and its semantics to allow remote verification of measurements per domain. We present an enhanced trust measurement architecture design, which produces domain specific integrity measurements suitable for fine-graded remote attestation. Providing domain specific integrity reports eases system and sub-system verification and yields desirable properties such as measurement log stability and constrained disclosure for multi-domain systems. We verify and prove the correctness of our trust measurement architecture using our formal model.