Preventing Denial-of-Service Attacks on a µ-Kernel for WebOSes

A goal of World-wide Web operating systems (WebOSes) is to enable clients to download executable content from servers connected to the World-wide Web (WWW). This will make applications more easily available to clients, but some of these applications may be malicious. Thus, a WebOS must be able to control the downloaded content's behavior. In this paper, we examine a speci c type of malicious activity: denial-of-service attacks using legal system operations. A denial-of-service attack occurs when an attacker prevents other users from performing their authorized operations even when the attacker may not be able to perform such operations. Current systems either do little to prevent denial-of-service attacks or have a limited scope of prevention of such attacks. For a WebOS, however, the ability to prevent denialof-service should be an integral part of the system. We are developing a WebOS using the L4 -kernel as its substrate. In this paper, we evaluate L4 as a basis of a system that can prevent denial-of-service attacks. In particular, we identify the -kernel-related resources are subject to denial-of-service attacks and de ne -kernel mechanisms to defend against such attacks. Our analysis demonstrates that system resource utilization can be managed by trusted, userlevel servers to prevent denial-of-service attacks on such resources.