Unified Defense against DDoS Attacks

Abstract. With DoS/DDoS attacks emerging as one of the primary security threats in today's Internet, the search is on for an efficient DDoS defense mechanism that would provide attack prevention, mitigation and traceback features, in as few packets as possible and with no collateral damage. Although several techniques have been proposed to tackle this growing menace, there exists no effective solution to date, due to the growing sophistication of the attacks and also the increasingly complex Internet architecture. In this paper, we propose an unified framework that integrates traceback and mitigation capabilities for an effective attack defense. Some significant aspects of our approach include: (1) a novel data cube model to represent the traceback information, and its slicing along the lines of path signatures rather than router signatures, (2) characterizing traceback as a transmission scheduling problem on the data cube representation, and achieving scheduling optimality using a novel metric called utility, (3) and finally an information delivery architecture employing both packet marking and data logging in a distributed manner to achieve faster response times. The proposed scheme can thus provide both per-packet mitigation and multi-packet traceback capabilities due to effective data slicing of the cube, and can attain higher detection speeds due to novel utility rate analysis. We also contrast this unified scheme with other well-known schemes in literature to understand the performance tradeoffs, while providing an experimental evaluation of the proposed scheme on real data sets

Traffic Monitoring and analysis for source identification

Ph.DDOCTOR OF PHILOSOPH

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

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

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

Multi-user resource-sharing problem for the Internet

In this thesis we study a series of multi-user resource-sharing problems for the Internet, which involve distribution of a common resource among participants of multi-user systems (servers or networks). We study concurrently accessible resources, which for end-users may be exclusively accessible or non-exclusively. For all kinds we suggest a separate algorithm or a modification of common reputation scheme. Every algorithm or method is studied from different perspectives: optimality of protocols, selfishness of end users, fairness of the protocol for end users. On the one hand the multifaceted analysis allows us to select the most suited protocols among a set of various available ones based on trade-offs of optima criteria. On the other hand, the future Internet predictions dictate new rules for the optimality we should take into account and new properties of the networks that cannot be neglected anymore. In this thesis we have studied new protocols for such resource-sharing problems as the backoff protocol, defense mechanisms against Denial-of-Service, fairness and confidentiality for users in overlay networks. For backoff protocol we present analysis of a general backoff scheme, where an optimization is applied to a general-view backoff function. It leads to an optimality condition for backoff protocols in both slot times and continuous time models. Additionally we present an extension for the backoff scheme in order to achieve fairness for the participants in an unfair environment, such as wireless signal strengths. Finally, for the backoff algorithm we suggest a reputation scheme that deals with misbehaving nodes. For the next problem -- denial-of-service attacks, we suggest two schemes that deal with the malicious behavior for two conditions: forged identities and unspoofed identities. For the first one we suggest a novel most-knocked-first-served algorithm, while for the latter we apply a reputation mechanism in order to restrict resource access for misbehaving nodes. Finally, we study the reputation scheme for the overlays and peer-to-peer networks, where resource is not placed on a common station, but spread across the network. The theoretical analysis suggests what behavior will be selected by the end station under such a reputation mechanism.Tässä väitöskirjassa tutkimme useita Internetin resurssienjako-ongelmia, jotka liittyvät yhteisten resurssien käyttöön ja jakamiseen monen käyttäjän järjestelmissä. Tutkimme rinnakkain käytettäviä resursseja, jotka voidaan antaa käyttäjille omaan tai jaettuun käyttöön. Ratkaisuna ehdotamme joko uutta algoritmia tai muutoksia olemassaoleviin tunnettuihin mainejärjestelmiin. Kaikkia algoritmeja tutkitaan useammasta näkökulmasta: protokollien optimaalisuus, käyttäjien itsekkyys, protokollan reiluus käytäjiä kohtaan. Tämä monikantainen analyysi mahdollistaa sopivimman protokollan valinnan, ottaen huomioon erilaiset optimointikriteerit. Toisaalta, tulevaisuuden verkkoratkaisut määrittelevät uusia optimointisääntöjä, sekä verkkojen uusia ominaisuuksia, jotka molemmat pitää ottaa tulevaisuudessa huomioon

GOSSIB vs. IP Traceback Rumors

To identify sources of distributed denial-of-service attacks, path traceback mechanisms have been proposed. Traceback mechanisms relying on probabilistic packet marking (PPM) have received most attention, as they are easy to implement and deploy incrementally. In this paper, we introduce a new concept, namely Groups Of Strongly SImilar Birthdays (GOSSIB), that can be used by to obtain effects similar to a successful birthday attack on PPM schemes. The original and most widely known IP traceback mechanism, compressed edge fragment sampling (CEFS), was developed by Savage et al. We analyze the effects of an attacker using GOSSIB against CEFS and show that the attacker can seed misinformation much more efficiently than the network is able to contribute real traceback information. Thus, GOSSIB will render PPM effectively useless. It can be expected that GOSSIB has similar effects on other PPM traceback schemes and that standard modifications to the systems will not solve the problem