A Framework for Denial of Service Analysis

Protocol-based denial-of-service attacks are currently one of the greatest threats to survivability. Since they are implemented using the very protocols used for establishing communication, they often do not require any special special privileges on the part of the attacker. Moreover, since most existing protocols were not designed to be resistant to these types of attacks, they are often very easy to implement. Attempts to make protocols more resistant to these types of attacks can run afoul of the fact that the very mechanisms that can be used to protect a system (e.g. cryptographic authentication) can also be used as a basis of a denial-of-service attacks themselves. Thus making a protocol resistant to denial-of-service attack can be a complex process that is hard to understand. In our research we have been trying to make the procedure of designing and evaluationg a denial-of-service resistant protocol more understandable by developing a framework for their analysis, concentrating on the most prevalent type of denial-of-service attack, resource flooding. Our work was originally intended for the analysis of cryptographic protocols, and is based on principles used in cryptographic protocol analysis. However, we believe it could be also applied to general communication protocols, and we dicuss this issue as well.