Mitigating Denial-of-Service Attacks in Mobile Ad Hoc Networks using Network Capabilities

MITIGATING DENIAL-OF-SERVICE ATTACKS IN MOBILE AD HOC NETWORKS USING NETWORK CAPABILITIES Eric J. Swankoski, PhD George Mason University, 2017 Dissertation Director: Dr. Sanjeev Setia The open nature of mobile ad hoc networks (MANETs) makes them vulnerable to denialof-service attacks. With no well-defined access points, network perimeter, or centralized authority, these networks are susceptible to attacks from one or more authorized nodes (insiders) or malicious external entities (outsiders). Mitigation methods for such attacks are critically important, and in this work we explore the use of network capabilities to enforce a deny-by-default network access control policy. While capabilities can minimize the damage caused by malicious adversaries, the aforementioned characteristics of MANETs also complicate the operation of capabilities. Traditional network capability mechanisms are not designed to cope with frequent route changes. The problem is not well-studied, either for unicast-based or multicast-based MANET communication. For unicast networks, we have developed EPIC (Efficient Path-Independent Capabilities), a method which combines reverse-disclosure hash chains, identity-based cryptography, and per-packet verification to support the establishment of destination-controlled pathindependent capabilities and to show how they can be efficiently operated and maintained in a high mobility environment. EPIC decouples the capability from any particular route, allowing for a seamless transition from one authorized route to another between a source and destination. We have also developed RAC (Route-Adaptive Capabilities), which uses the same basic building blocks of EPIC but combines the high security of route-dependent capabilities with dynamic route reconfiguration to maintain high efficiency and performance. For multicast networks, we have developed EPIC-M (Multicast), which builds on the core aspects of EPIC to provide capability functionality in multicast networks. EPIC-M uses the building blocks of EPIC, but also utilizes threshold cryptography (partial digital signatures) to facilitate capability establishment and decouple capability establishment and maintenance from multicast routing and membership operations. We show through simulations that EPIC, RAC and EPIC-M can operate efficiently in well-behaved networks while also minimizing network disruption caused by malicious entities in hostile or unsecured networks. Chapter 1: Introduction Mobile ad hoc networks (MANETs) offer a high degree of flexibility in many regards, offering substantial advantages over fixed-topology networks. This flexibility, however, leads to additional security complications. The unconstrained physical structure of MANETs does not lend itself well to a secure architecture with no well-defined access points or network perimeter, any node, malicious or benign, can enter the network and attempt to launch attacks many of them particularly difficult to mitigate. In recent years, there has been a great deal of research on securing MANETs [1,2]. Several authors have proposed novel approaches for secure key establishment, secure neighbor discovery, and secure routing, among others [3–6]. A critically important issue that still remains to be fully addressed is the problem of preventing or mitigating denial-of-service attacks launched by malicious or compromised nodes. DoS attacks in MANETs are both difficult to detect and defend against; nodes may act alone to conduct denial-of-service attacks or they may collude with other malicious nodes for maximum effect. Attacks can be launched both by outside adversaries (entities external to the network) and insider adversaries (nodes that are members of the target network). Insider attacks are particularly problematic as these nodes are compromised or malicious nodes that possess the proper authorization and credentials to access the network and as such are difficult to differentiate from legitimate participants. Most existing security mechanisms are designed to protect against outsider attacks, but insiders authorized network nodes are more difficult to detect and defend against.