On mitigating distributed denial of service attacks

Denial of service (DoS) attacks and distributed denial of service (DDoS) attacks are probably the most ferocious threats in the Internet, resulting in tremendous economic and social implications/impacts on our daily lives that are increasingly depending on the wellbeing of the Internet. How to mitigate these attacks effectively and efficiently has become an active research area. The critical issues here include 1) IP spoofing, i.e., forged source lIP addresses are routinely employed to conceal the identities of the attack sources and deter the efforts of detection, defense, and tracing; 2) the distributed nature, that is, hundreds or thousands of compromised hosts are orchestrated to attack the victim synchronously. Other related issues are scalability, lack of incentives to deploy a new scheme, and the effectiveness under partial deployment. This dissertation investigates and proposes effective schemes to mitigate DDoS attacks. It is comprised of three parts. The first part introduces the classification of DDoS attacks and the evaluation of previous schemes. The second part presents the proposed IP traceback scheme, namely, autonomous system-based edge marking (ASEM). ASEM enhances probabilistic packet marking (PPM) in several aspects: (1) ASEM is capable of addressing large-scale DDoS attacks efficiently; (2) ASEM is capable of handling spoofed marking from the attacker and spurious marking incurred by subverted routers, which is a unique and critical feature; (3) ASEM can significantly reduce the number of marked packets required for path reconstruction and suppress false positives as well. The third part presents the proposed DDoS defense mechanisms, including the four-color-theorem based path marking, and a comprehensive framework for DDoS defense. The salient features of the framework include (1) it is designed to tackle a wide spectrum of DDoS attacks rather than a specified one, and (2) it can differentiate malicious traffic from normal ones. The receiver-center design avoids several related issues such as scalability, and lack of incentives to deploy a new scheme. Finally, conclusions are drawn and future works are discussed

A composable approach to design of newer techniques for large-scale denial-of-service attack attribution

Since its early days, the Internet has witnessed not only a phenomenal growth, but also a large number of security attacks, and in recent years, denial-of-service (DoS) attacks have emerged as one of the top threats. The stateless and destination-oriented Internet routing combined with the ability to harness a large number of compromised machines and the relative ease and low costs of launching such attacks has made this a hard problem to address. Additionally, the myriad requirements of scalability, incremental deployment, adequate user privacy protections, and appropriate economic incentives has further complicated the design of DDoS defense mechanisms. While the many research proposals to date have focussed differently on prevention, mitigation, or traceback of DDoS attacks, the lack of a comprehensive approach satisfying the different design criteria for successful attack attribution is indeed disturbing. Our first contribution here has been the design of a composable data model that has helped us represent the various dimensions of the attack attribution problem, particularly the performance attributes of accuracy, effectiveness, speed and overhead, as orthogonal and mutually independent design considerations. We have then designed custom optimizations along each of these dimensions, and have further integrated them into a single composite model, to provide strong performance guarantees. Thus, the proposed model has given us a single framework that can not only address the individual shortcomings of the various known attack attribution techniques, but also provide a more wholesome counter-measure against DDoS attacks. Our second contribution here has been a concrete implementation based on the proposed composable data model, having adopted a graph-theoretic approach to identify and subsequently stitch together individual edge fragments in the Internet graph to reveal the true routing path of any network data packet. The proposed approach has been analyzed through theoretical and experimental evaluation across multiple metrics, including scalability, incremental deployment, speed and efficiency of the distributed algorithm, and finally the total overhead associated with its deployment. We have thereby shown that it is realistically feasible to provide strong performance and scalability guarantees for Internet-wide attack attribution. Our third contribution here has further advanced the state of the art by directly identifying individual path fragments in the Internet graph, having adopted a distributed divide-and-conquer approach employing simple recurrence relations as individual building blocks. A detailed analysis of the proposed approach on real-life Internet topologies with respect to network storage and traffic overhead, has provided a more realistic characterization. Thus, not only does the proposed approach lend well for simplified operations at scale but can also provide robust network-wide performance and security guarantees for Internet-wide attack attribution. Our final contribution here has introduced the notion of anonymity in the overall attack attribution process to significantly broaden its scope. The highly invasive nature of wide-spread data gathering for network traceback continues to violate one of the key principles of Internet use today - the ability to stay anonymous and operate freely without retribution. In this regard, we have successfully reconciled these mutually divergent requirements to make it not only economically feasible and politically viable but also socially acceptable. This work opens up several directions for future research - analysis of existing attack attribution techniques to identify further scope for improvements, incorporation of newer attributes into the design framework of the composable data model abstraction, and finally design of newer attack attribution techniques that comprehensively integrate the various attack prevention, mitigation and traceback techniques in an efficient manner

A Robust Mechanism for Defending Distributed Denial OF Service Attacks on Web Servers

Distributed Denial of Service (DDoS) attacks have emerged as a popular means of causing mass targeted service disruptions, often for extended periods of time. The relative ease and low costs of launching such attacks, supplemented by the current inadequate sate of any viable defense mechanism, have made them one of the top threats to the Internet community today. Since the increasing popularity of web-based applications has led to several critical services being provided over the Internet, it is imperative to monitor the network traffic so as to prevent malicious attackers from depleting the resources of the network and denying services to legitimate users. This paper first presents a brief discussion on some of the important types of DDoS attacks that currently exist and some existing mechanisms to combat these attacks. It then points out the major drawbacks of the currently existing defense mechanisms and proposes a new mechanism for protecting a web-server against a DDoS attack. In the proposed mechanism, incoming traffic to the server is continuously monitored and any abnormal rise in the inbound traffic is immediately detected. The detection algorithm is based on a statistical analysis of the inbound traffic on the server and a robust hypothesis testing framework. Simulations carried out on the proposed mechanism have produced results that demonstrate effectiveness of the proposed defense mechanism against DDoS attacks.Comment: 18 pages, 3 figures, 5 table

Controlling High Bandwidth Aggregates in the Network

The current Internet infrastructure has very few built-in protection mechanisms, and is therefore vulnerable to attacks and failures. In particular, recent events have illustrated the Internet's vulnerability to both denial of service (DoS) attacks and flash crowds in which one or more links in the network (or servers at the edge of the network) become severely congested. In both DoS attacks and flash crowds the congestion is due neither to a single flow, nor to a general increase in traffic, but to a well-defined subset of the traffic --- an aggregate. This paper proposes mechanisms for detecting and controlling such high bandwidth aggregates. Our design involves both a local mechanism for detecting and controlling an aggregate at a single router, and a cooperative pushback mechanism in which a router can ask upstream routers to control an aggregate. While certainly not a panacea, these mechanisms could provide some needed relief from flash crowds and flooding-style DoS attacks. The presentation in this paper is a first step towards a more rigorous evaluation of these mechanisms

Towards IP traceback based defense against DDoS attacks.

Lau Nga Sin.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.Includes bibliographical references (leaves 101-110).Abstracts in English and Chinese.Abstract --- p.iAcknowledgement --- p.ivChapter 1 --- Introduction --- p.1Chapter 1.1 --- Research Motivation --- p.2Chapter 1.2 --- Problem Statement --- p.3Chapter 1.3 --- Research Objectives --- p.4Chapter 1.4 --- Structure of the Thesis --- p.6Chapter 2 --- Background Study on DDoS Attacks --- p.8Chapter 2.1 --- Distributed Denial of Service Attacks --- p.8Chapter 2.1.1 --- DDoS Attack Architecture --- p.9Chapter 2.1.2 --- DDoS Attack Taxonomy --- p.11Chapter 2.1.3 --- DDoS Tools --- p.19Chapter 2.1.4 --- DDoS Detection --- p.21Chapter 2.2 --- DDoS Countermeasure: Attack Source Traceback --- p.23Chapter 2.2.1 --- Link Testing --- p.23Chapter 2.2.2 --- Logging --- p.24Chapter 2.2.3 --- ICMP-based traceback --- p.26Chapter 2.2.4 --- Packet marking --- p.28Chapter 2.2.5 --- Comparison of various IP Traceback Schemes --- p.31Chapter 2.3 --- DDoS Countermeasure: Packet Filtering --- p.33Chapter 2.3.1 --- Ingress Filtering --- p.33Chapter 2.3.2 --- Egress Filtering --- p.34Chapter 2.3.3 --- Route-based Packet Filtering --- p.35Chapter 2.3.4 --- IP Traceback-based Packet Filtering --- p.36Chapter 2.3.5 --- Router-based Pushback --- p.37Chapter 3 --- Domain-based IP Traceback Scheme --- p.40Chapter 3.1 --- Overview of our IP Traceback Scheme --- p.41Chapter 3.2 --- Assumptions --- p.44Chapter 3.3 --- Proposed Packet Marking Scheme --- p.45Chapter 3.3.1 --- IP Markings with Edge Sampling --- p.46Chapter 3.3.2 --- Domain-based Design Motivation --- p.48Chapter 3.3.3 --- Mathematical Principle --- p.49Chapter 3.3.4 --- Marking Mechanism --- p.51Chapter 3.3.5 --- Storage Space of the Marking Fields --- p.56Chapter 3.3.6 --- Packet Marking Integrity --- p.57Chapter 3.3.7 --- Path Reconstruction --- p.58Chapter 4 --- Route-based Packet Filtering Scheme --- p.62Chapter 4.1 --- Placement of Filters --- p.63Chapter 4.1.1 --- At Sources' Networks --- p.64Chapter 4.1.2 --- At Victim's Network --- p.64Chapter 4.2 --- Proposed Packet Filtering Scheme --- p.65Chapter 4.2.1 --- Classification of Packets --- p.66Chapter 4.2.2 --- Filtering Mechanism --- p.67Chapter 5 --- Performance Evaluation --- p.70Chapter 5.1 --- Simulation Setup --- p.70Chapter 5.2 --- Experiments on IP Traceback Scheme --- p.72Chapter 5.2.1 --- Performance Metrics --- p.72Chapter 5.2.2 --- Choice of Marking Probabilities --- p.73Chapter 5.2.3 --- Experimental Results --- p.75Chapter 5.3 --- Experiments on Packet Filtering Scheme --- p.82Chapter 5.3.1 --- Performance Metrics --- p.82Chapter 5.3.2 --- Choices of Filtering Probabilities --- p.84Chapter 5.3.3 --- Experimental Results --- p.85Chapter 5.4 --- Deployment Issues --- p.91Chapter 5.4.1 --- Backward Compatibility --- p.91Chapter 5.4.2 --- Processing Overheads to the Routers and Network --- p.93Chapter 5.5 --- Evaluations --- p.95Chapter 6 --- Conclusion --- p.96Chapter 6.1 --- Contributions --- p.96Chapter 6.2 --- Discussions and future work --- p.99Bibliography --- p.11

Adaptive Response System for Distributed Denial-of-Service Attacks

The continued prevalence and severe damaging effects of the Distributed Denial of Service (DDoS) attacks in today’s Internet raise growing security concerns and call for an immediate response to come up with better solutions to tackle DDoS attacks. The current DDoS prevention mechanisms are usually inflexible and determined attackers with knowledge of these mechanisms, could work around them. Most existing detection and response mechanisms are standalone systems which do not rely on adaptive updates to mitigate attacks. As different responses vary in their “leniency” in treating detected attack traffic, there is a need for an Adaptive Response System. We designed and implemented our DDoS Adaptive ResponsE (DARE) System, which is a distributed DDoS mitigation system capable of executing appropriate detection and mitigation responses automatically and adaptively according to the attacks. It supports easy integrations for both signature-based and anomaly-based detection modules. Additionally, the design of DARE’s individual components takes into consideration the strengths and weaknesses of existing defence mechanisms, and the characteristics and possible future mutations of DDoS attacks. These components consist of an Enhanced TCP SYN Attack Detector and Bloom-based Filter, a DDoS Flooding Attack Detector and Flow Identifier, and a Non Intrusive IP Traceback mechanism. The components work together interactively to adapt the detections and responses in accordance to the attack types. Experiments conducted on DARE show that the attack detection and mitigation are successfully completed within seconds, with about 60% to 86% of the attack traffic being dropped, while availability for legitimate and new legitimate requests is maintained. DARE is able to detect and trigger appropriate responses in accordance to the attacks being launched with high accuracy, effectiveness and efficiency. We also designed and implemented a Traffic Redirection Attack Protection System (TRAPS), a stand-alone DDoS attack detection and mitigation system for IPv6 networks. In TRAPS, the victim under attack verifies the authenticity of the source by performing virtual relocations to differentiate the legitimate traffic from the attack traffic. TRAPS requires minimal deployment effort and does not require modifications to the Internet infrastructure due to its incorporation of the Mobile IPv6 protocol. Experiments to test the feasibility of TRAPS were carried out in a testbed environment to verify that it would work with the existing Mobile IPv6 implementation. It was observed that the operations of each module were functioning correctly and TRAPS was able to successfully mitigate an attack launched with spoofed source IP addresses

Intrusion detection routers: Design, implementation and evaluation using an experimental testbed

In this paper, we present the design, the implementation details, and the evaluation results of an intrusion detection and defense system for distributed denial-of-service (DDoS) attack. The evaluation is conducted using an experimental testbed. The system, known as intrusion detection router (IDR), is deployed on network routers to perform online detection on any DDoS attack event, and then react with defense mechanisms to mitigate the attack. The testbed is built up by a cluster of sufficient number of Linux machines to mimic a portion of the Internet. Using the testbed, we conduct real experiments to evaluate the IDR system and demonstrate that IDR is effective in protecting the network from various DDoS attacks. © 2006 IEEE.published_or_final_versio

IP traceback marking scheme based DDoS defense.

Ping Yan.Thesis submitted in: December 2004.Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.Includes bibliographical references (leaves 93-100).Abstracts in English and Chinese.Abstract --- p.iAcknowledgement --- p.iiiChapter 1 --- INTRODUCTION --- p.1Chapter 1.1 --- The Problem --- p.1Chapter 1.2 --- Research Motivations and Objectives --- p.3Chapter 1.3 --- The Rationale --- p.8Chapter 1.4 --- Thesis Organization --- p.9Chapter 2 --- BACKGROUND STUDY --- p.10Chapter 2.1 --- Distributed Denial of Service Attacks --- p.10Chapter 2.1.1 --- Taxonomy of DoS and DDoS Attacks --- p.13Chapter 2.2 --- IP Traceback --- p.17Chapter 2.2.1 --- Assumptions --- p.18Chapter 2.2.2 --- Problem Model and Performance Metrics --- p.20Chapter 2.3 --- IP Traceback Proposals --- p.24Chapter 2.3.1 --- Probabilistic Packet Marking (PPM) --- p.24Chapter 2.3.2 --- ICMP Traceback Messaging --- p.26Chapter 2.3.3 --- Logging --- p.27Chapter 2.3.4 --- Tracing Hop-by-hop --- p.29Chapter 2.3.5 --- Controlled Flooding --- p.30Chapter 2.4 --- DDoS Attack Countermeasures --- p.30Chapter 2.4.1 --- Ingress/Egress Filtering --- p.33Chapter 2.4.2 --- Route-based Distributed Packet Filtering (DPF) --- p.34Chapter 2.4.3 --- IP Traceback Based Intelligent Packet Filtering --- p.35Chapter 2.4.4 --- Source-end DDoS Attack Recognition and Defense --- p.36Chapter 2.4.5 --- Classification of DDoS Defense Methods --- p.38Chapter 3 --- ADAPTIVE PACKET MARKING SCHEME --- p.41Chapter 3.1 --- Scheme Overview --- p.41Chapter 3.2 --- Adaptive Packet Marking Scheme --- p.44Chapter 3.2.1 --- Design Motivation --- p.44Chapter 3.2.2 --- Marking Algorithm Basics --- p.46Chapter 3.2.3 --- Domain id Marking --- p.49Chapter 3.2.4 --- Router id Marking --- p.51Chapter 3.2.5 --- Attack Graph Reconstruction --- p.53Chapter 3.2.6 --- IP Header Overloading --- p.56Chapter 3.3 --- Experiments on the Packet Marking Scheme --- p.59Chapter 3.3.1 --- Simulation Set-up --- p.59Chapter 3.3.2 --- Experimental Results and Analysis --- p.61Chapter 4 --- DDoS DEFENSE SCHEMES --- p.67Chapter 4.1 --- Scheme I: Packet Filtering at Victim-end --- p.68Chapter 4.1.1 --- Packet Marking Scheme Modification --- p.68Chapter 4.1.2 --- Packet Filtering Algorithm --- p.69Chapter 4.1.3 --- Determining the Filtering Probabilities --- p.70Chapter 4.1.4 --- Suppressing Packets Filtering with did Markings from Nearby Routers --- p.73Chapter 4.2 --- Scheme II: Rate Limiting at the Sources --- p.73Chapter 4.2.1 --- Algorithm of the Rate-limiting Scheme --- p.74Chapter 4.3 --- Performance Measurements for Scheme I & Scheme II . --- p.77Chapter 5 --- CONCLUSION --- p.87Chapter 5.1 --- Contributions --- p.87Chapter 5.2 --- Discussion and Future Work --- p.91Bibliography --- p.10

Hybrid traceback-filtering (HTF): An efficient DoS/DDoS defense mechanism

Master'sMASTER OF SCIENC