Preventing Denial-of-Service Attalcks on a, p-Kernel for WebOSes

A goal of World-wide Web operating systems (WebOSes) is to enabie clients to download executable content from servers connected to the World-wide Web (WWW). This will make applications more easily available to clients, but s0m.e 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 specific type of malicious activity: denialof- service attacks using legal system operations. ‘4 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 denial-of-service should be un integral part of the system. We are developing a WebOS using the L4 p-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 p-kernel-related resources which are subject to denial-of-service attacks and define pkernel mechanisms to defend against such, attacks. Our analysis demonstrates that system resource utilisation can be managed by trusted, user-level seruers to prevent denial-of-service attacks on ruth resources.