Section: New Results

Online Risk Management

Participants : Rémi Badonnel [contact] , Oussema Dabbebi, Olivier Festor.

Telephony over IP has known a large scale deployment and has been supported by the standardization of dedicated signaling protocols. This service is however exposed to multiple attacks due to a lower confinement in comparison to traditional PSTN networks. While a large variety of methods and techniques has been proposed for protecting VoIP networks, their activation may seriously impact on the quality of such a critical service. Risk management provides new opportunities for addressing this challenge. In particular our work aims at performing online risk management for VoIP networks and services. The objective is to dynamically adapt the service exposure with respect to the threat potentiality, while maintaining a low security overhead.

In the year 2013, these efforts on VoIP risk management have led the PhD defense of Oussema Dabbebi. This work has been structured into three axes [1] . The first axis concerns the automation of the risk management process in VoIP enterprise network. In this context, we have developed a mathematical model for assessing risk, a set of progressive countermeasures to counter attackers and mitigation algorithms that evaluate the risk level and takes the decision to activate a subset of countermeasures [4] . To improve our strategy, we have coupled it with an anomaly detection system based on SVM and a self-configuration mechanism which provides feedback about countermeasure efficiency. The second axis deals with the extension of our adaptive risk strategy to P2PSIP infrastructures. We have implemented a specific risk model and a dedicated set of countermeasures with respect to its peer-to-peer nature. For that, we have identified attack sources and established different threat scenarios. We have analysed the RELOAD framework and proposed trust mechanisms to address its residual attacks. Finally, the third axis focuses on VoIP services in the cloud where we have proposed a risk strategy and several strategies to deploy and apply countermeasures [5] .