A Case Study on Covert Channel Establishment via Software Caches in High-Assurance Computing Systems
This highlights a security vulnerability in high-assurance systems, emphasizing the need for careful design in operating system architectures, though it is incremental as it builds on known covert channel concepts.
The study demonstrated that covert timing channels can be established via software caches in high-assurance computing systems, showing vulnerabilities even in security-focused architectures, and proposed a method to disrupt such channels.
Covert channels can be utilized to secretly deliver information from high privileged processes to low privileged processes in the context of a high-assurance computing system. In this case study, we investigate the possibility of covert channel establishment via software caches in the context of a framework for component-based operating systems. While component-based operating systems offer security through the encapsulation of system service processes, complete isolation of these processes is not reasonably feasible. This limitation is practically demonstrated with our concept of a specific covert timing channel based on file system caching. The stability of the covert channel is evaluated and a methodology to disrupt the covert channel transmission is presented. While these kinds of attacks are not limited to high-assurance computing systems, our study practically demonstrates that even security-focused computing systems with a minimal trusted computing base are vulnerable for such kinds of attacks and careful design decisions are necessary for secure operating system architectures.