A Proactive DOS Filter Mechanism for Delay Tolerant Networks

Denial of Service (DOS) attacks are a major threat faced by all types of networks. The effect of DOS in a delay tolerant network (DTN) is even more aggravated due to the scarcity of resources. Perpetrators of DOS attacks in DTN-like environments look beyond the objective of rendering a target node useless. The aim of an attacker is to cause a network-wide degradation of resources, service and performance. This can easily be achieved by exhausting node or link resources and partitioning the network. In this paper we seek to provide a proactive approach in making the DTN authentication process robust against DOS. Our aim is to make security protocols which provide mandatory DTN security services resilient to DOS attacks. The overall objective is to make it hard to launch a DOS attack and ensure the availability of DTN services. A DTN-cookie mechanism has been proposed to quickly identify and filter out illegitimate traffic

Keeping Authorities "Honest or Bust" with Decentralized Witness Cosigning

The secret keys of critical network authorities - such as time, name, certificate, and software update services - represent high-value targets for hackers, criminals, and spy agencies wishing to use these keys secretly to compromise other hosts. To protect authorities and their clients proactively from undetected exploits and misuse, we introduce CoSi, a scalable witness cosigning protocol ensuring that every authoritative statement is validated and publicly logged by a diverse group of witnesses before any client will accept it. A statement S collectively signed by W witnesses assures clients that S has been seen, and not immediately found erroneous, by those W observers. Even if S is compromised in a fashion not readily detectable by the witnesses, CoSi still guarantees S's exposure to public scrutiny, forcing secrecy-minded attackers to risk that the compromise will soon be detected by one of the W witnesses. Because clients can verify collective signatures efficiently without communication, CoSi protects clients' privacy, and offers the first transparency mechanism effective against persistent man-in-the-middle attackers who control a victim's Internet access, the authority's secret key, and several witnesses' secret keys. CoSi builds on existing cryptographic multisignature methods, scaling them to support thousands of witnesses via signature aggregation over efficient communication trees. A working prototype demonstrates CoSi in the context of timestamping and logging authorities, enabling groups of over 8,000 distributed witnesses to cosign authoritative statements in under two seconds.Comment: 20 pages, 7 figure

Architecture, Services and Protocols for CRUTIAL

This document describes the complete specification of the architecture, services and protocols of the project CRUTIAL. The CRUTIAL Architecture intends to reply to a grand challenge of computer science and control engineering: how to achieve resilience of critical information infrastructures (CII), in particular in the electrical sector. In general lines, the document starts by presenting the main architectural options and components of the architecture, with a special emphasis on a protection device called the CRUTIAL Information Switch (CIS). Given the various criticality levels of the equipments that have to be protected, and the cost of using a replicated device, we define a hierarchy of CIS designs incrementally more resilient. The different CIS designs offer various trade offs in terms of capabilities to prevent and tolerate intrusions, both in the device itself and in the information infrastructure. The Middleware Services, APIs and Protocols chapter describes our approach to intrusion tolerant middleware. The CRUTIAL middleware comprises several building blocks that are organized on a set of layers. The Multipoint Network layer is the lowest layer of the middleware, and features an abstraction of basic communication services, such as provided by standard protocols, like IP, IPsec, UDP, TCP and SSL/TLS. The Communication Support layer features three important building blocks: the Randomized Intrusion-Tolerant Services (RITAS), the CIS Communication service and the Fosel service for mitigating DoS attacks. The Activity Support layer comprises the CIS Protection service, and the Access Control and Authorization service. The Access Control and Authorization service is implemented through PolyOrBAC, which defines the rules for information exchange and collaboration between sub-modules of the architecture, corresponding in fact to different facilities of the CII’s organizations. The Monitoring and Failure Detection layer contains a definition of the services devoted to monitoring and failure detection activities. The Runtime Support Services, APIs, and Protocols chapter features as a main component the Proactive-Reactive Recovery service, whose aim is to guarantee perpetual correct execution of any components it protects.Project co-funded by the European Commission within the Sixth Frame-work Programme (2002-2006

A critical review of cyber-physical security for building automation systems

Modern Building Automation Systems (BASs), as the brain that enables the smartness of a smart building, often require increased connectivity both among system components as well as with outside entities, such as optimized automation via outsourced cloud analytics and increased building-grid integrations. However, increased connectivity and accessibility come with increased cyber security threats. BASs were historically developed as closed environments with limited cyber-security considerations. As a result, BASs in many buildings are vulnerable to cyber-attacks that may cause adverse consequences, such as occupant discomfort, excessive energy usage, and unexpected equipment downtime. Therefore, there is a strong need to advance the state-of-the-art in cyber-physical security for BASs and provide practical solutions for attack mitigation in buildings. However, an inclusive and systematic review of BAS vulnerabilities, potential cyber-attacks with impact assessment, detection & defense approaches, and cyber-secure resilient control strategies is currently lacking in the literature. This review paper fills the gap by providing a comprehensive up-to-date review of cyber-physical security for BASs at three levels in commercial buildings: management level, automation level, and field level. The general BASs vulnerabilities and protocol-specific vulnerabilities for the four dominant BAS protocols are reviewed, followed by a discussion on four attack targets and seven potential attack scenarios. The impact of cyber-attacks on BASs is summarized as signal corruption, signal delaying, and signal blocking. The typical cyber-attack detection and defense approaches are identified at the three levels. Cyber-secure resilient control strategies for BASs under attack are categorized into passive and active resilient control schemes. Open challenges and future opportunities are finally discussed.Comment: 38 pages, 7 figures, 6 tables, submitted to Annual Reviews in Contro

Diverse Intrusion-tolerant Systems

Over the past 20 years, there have been indisputable advances on the development of Byzantine Fault-Tolerant (BFT) replicated systems. These systems keep operational safety as long as at most f out of n replicas fail simultaneously. Therefore, in order to maintain correctness it is assumed that replicas do not suffer from common mode failures, or in other words that replicas fail independently. In an adversarial setting, this requires that replicas do not include similar vulnerabilities, or otherwise a single exploit could be employed to compromise a significant part of the system. The thesis investigates how this assumption can be substantiated in practice by exploring diversity when managing the configurations of replicas. The thesis begins with an analysis of a large dataset of vulnerability information to get evidence that diversity can contribute to failure independence. In particular, we used the data from a vulnerability database to devise strategies for building groups of n replicas with different Operating Systems (OS). Our results demonstrate that it is possible to create dependable configurations of OSes, which do not share vulnerabilities over reasonable periods of time (i.e., a few years). Then, the thesis proposes a new design for a firewall-like service that protects and regulates the access to critical systems, and that could benefit from our diversity management approach. The solution provides fault and intrusion tolerance by implementing an architecture based on two filtering layers, enabling efficient removal of invalid messages at early stages in order to decrease the costs associated with BFT replication in the later stages. The thesis also presents a novel solution for managing diverse replicas. It collects and processes data from several data sources to continuously compute a risk metric. Once the risk increases, the solution replaces a potentially vulnerable replica by another one, trying to maximize the failure independence of the replicated service. Then, the replaced replica is put on quarantine and updated with the available patches, to be prepared for later re-use. We devised various experiments that show the dependability gains and performance impact of our prototype, including key benchmarks and three BFT applications (a key-value store, our firewall-like service, and a blockchain).Unidade de investigação LASIGE (UID/CEC/00408/2019) e o projeto PTDC/EEI-SCR/1741/2041 (Abyss

An efficient pending interest table control management in named data network

Named Data Networking (NDN) is an emerging Internet architecture that employs a new network communication model based on the identity of Internet content. Its core component, the Pending Interest Table (PIT) serves a significant role of recording Interest packet information which is ready to be sent but in waiting for matching Data packet. In managing PIT, the issue of flow PIT sizing has been very challenging due to massive use of long Interest lifetime particularly when there is no flexible replacement policy, hence affecting PIT performance. The aim of this study is to propose an efficient PIT Control Management (PITCM) approach to be used in handling incoming Interest packets in order to mitigate PIT overflow thus enhancing PIT utilization and performance. PITCM consists of Adaptive Virtual PIT (AVPIT) mechanism, Smart Threshold Interest Lifetime (STIL) mechanism and Highest Lifetime Least Request (HLLR) policy. The AVPIT is responsible for obtaining early PIT overflow prediction and reaction. STIL is meant for adjusting lifetime value for incoming Interest packet while HLLR is utilized for managing PIT entries in efficient manner. A specific research methodology is followed to ensure that the work is rigorous in achieving the aim of the study. The network simulation tool is used to design and evaluate PITCM. The results of study show that PITCM outperforms the performance of standard NDN PIT with 45% higher Interest satisfaction rate, 78% less Interest retransmission rate and 65% less Interest drop rate. In addition, Interest satisfaction delay and PIT length is reduced significantly to 33% and 46%, respectively. The contribution of this study is important for Interest packet management in NDN routing and forwarding systems. The AVPIT and STIL mechanisms as well as the HLLR policy can be used in monitoring, controlling and managing the PIT contents for Internet architecture of the future

DoS and DDoS Attacks: Defense, Detection and Traceback Mechanisms - A Survey

Denial of Service (DoS) or Distributed Denial of Service (DDoS) attacks are typically explicit attempts to exhaust victim2019;s bandwidth or disrupt legitimate users2019; access to services. Traditional architecture of internet is vulnerable to DDoS attacks and it provides an opportunity to an attacker to gain access to a large number of compromised computers by exploiting their vulnerabilities to set up attack networks or Botnets. Once attack network or Botnet has been set up, an attacker invokes a large-scale, coordinated attack against one or more targets. Asa result of the continuous evolution of new attacks and ever-increasing range of vulnerable hosts on the internet, many DDoS attack Detection, Prevention and Traceback mechanisms have been proposed, In this paper, we tend to surveyed different types of attacks and techniques of DDoS attacks and their countermeasures. The significance of this paper is that the coverage of many aspects of countering DDoS attacks including detection, defence and mitigation, traceback approaches, open issues and research challenges