In this paper, we present the architecture of CoBFIT, a component-based framework for building intrusion-tolerant distributed systems. The CoBFIT framework, by virtue of its design and implementation principles, can serve as a convenient base for building components that implement intrusion-tolerant protocols and for combining these components in an efficient manner to provide a number of services for dependability. For example, in this paper, we describe the CoBFIT implementation of a prototype intrusion-tolerant group communication system that includes services such as reliable multicast, group membership management, and total ordering of multicast messages.