Practical Hash-based Anonymity for MAC Addresses

Given that a MAC address can uniquely identify a person or a vehicle, continuous tracking over a large geographical scale has raised serious privacy concerns amongst governments and the general public. Prior work has demonstrated that simple hash-based approaches to anonymization can be easily inverted due to the small search space of MAC addresses. In particular, it is possible to represent the entire allocated MAC address space in 39 bits and that frequency-based attacks allow for 50% of MAC addresses to be enumerated in 31 bits. We present a practical approach to MAC address anonymization using both computationally expensive hash functions and truncating the resulting hashes to allow for k-anonymity. We provide an expression for computing the percentage of expected collisions, demonstrating that for digests of 24 bits it is possible to store up to 168,617 MAC addresses with the rate of collisions less than 1%. We experimentally demonstrate that a rate of collision of 1% or less can be achieved by storing data sets of 100 MAC addresses in 13 bits, 1,000 MAC addresses in 17 bits and 10,000 MAC addresses in 20 bits.Comment: Accepted at the 17th International Conference on Security and Cryptography (SECRYPT 2020). To be presented between 8-10 July 202

Using Deception to Enhance Security: A Taxonomy, Model, and Novel Uses

As the convergence between our physical and digital worlds continue at a rapid pace, securing our digital information is vital to our prosperity. Most current typical computer systems are unwittingly helpful to attackers through their predictable responses. In everyday security, deception plays a prominent role in our lives and digital security is no different. The use of deception has been a cornerstone technique in many successful computer breaches. Phishing, social engineering, and drive-by-downloads are some prime examples. The work in this dissertation is structured to enhance the security of computer systems by using means of deception and deceit

From Attack to Defense: Building Systems Secure against Breached Credentials

213 pagesTargeted attacks using breached credentials exploit the fact that users reuse some semantic or syntactic structure of passwords across websites to make them easy to remember. The adversary tries to log in to a victim’s account using thestolen passwords or variants of these passwords. Protecting accounts from these attacks remains challenging. Adversaries have wide-scale access to billions of stolen credentials from breach compilations, while users and identity providers remain in the dark about which accounts require attention. Our contribution is to show that it is possible to build a large-scale system that allows users to check for vulnerabilities against these attacks without sacrificing the functionality, security, and performance properties. We initiate the work by addressing the core challenge — modeling how humans choose similar passwords. We train models using modern machine learning techniques and exhibit its efficacy by simulating the most damaging attack to date. Then we formalize the security goals for existing breach checking services that warn if the exact credential is publicly exposed. In the process we also propose novel exact-checking protocols with better security guarantees. All this helps educate the design of the second-generation, similarity-aware, and privacy-preserving credential checking service — Might I get Pwned (MIGP). Finally, we collaborate with Cloudflare to deploy MIGP as part of the web application firewall to notify login servers about potential attacks

Backup To The Rescue: Automated Forensic Techniques For Advanced Website-Targeting Cyber Attacks

The last decade has seen a significant rise in non-technical users gaining a web presence, often via the easy-to-use functionalities of Content Management Systems (CMS). In fact, over 60% of the world’s websites run on CMSs. Unfortunately, this huge user population has made CMS-based websites a high-profile target for hackers. Worse still, the vast majority of the website hosting industry has shifted to a “backup and restore” model of security, which relies on error-prone AV scanners to prompt non-technical users to roll back to a pre-infection nightly snapshot. My cyber forensics research directly addresses this emergent problem by developing next-generation techniques for the investigation of advanced cyber crimes. Driven by economic incentives, attackers abuse the trust in this economy: selling malware on legitimate marketplaces, pirating popular website plugins, and infecting websites post-deployment. Furthermore, attackers are exploiting these websites at scale by carelessly dropping thousands of obfuscated and packed malicious files on the webserver. This is counter-intuitive since attackers are assumed to be stealthy. Despite the rise in web attacks, efficiently locating and accurately analyzing the malware dropped on compromised webservers has remained an open research challenge. This dissertation posits that the already collected webserver nightly backup snapshots contain all required information to enable automated and scalable detection of website compromises. This dissertation presents a web attack forensics framework that leverages program analysis to automatically understand the webserver’s nightly backup snapshots. This will enable the recovery of temporal phases of a webserver compromise and its origin within the website supply chain.Ph.D

Securing the Internet with digital signatures

The security and reliability of the Internet are essential for many functions of a modern society. Currently, the Internet lacks efficient network level security solutions and is vulnerable to various attacks, especially to distributed denial-of-service attacks. Traditional end-to-end security solutions such as IPSec only protect the communication end-points and are not effective if the underlying network infrastructure is attacked and paralyzed. This thesis describes and evaluates Packet Level Authentication (PLA), which is a novel method to secure the network infrastructure and provide availability with public key digital signatures. PLA allows any node in the network to verify independently the authenticity and integrity of every received packet, without previously established relationships with the sender or intermediate nodes that have handled the packet. As a result, various attacks against the network and its users can be more easily detected and mitigated, before they can cause significant damage or disturbance. PLA is compatible with the existing Internet infrastructure, and can be used with complementary end-to-end security solutions, such as IPSec and HIP. While PLA was originally designed for securing current IP networks, it is also suitable for securing future data-oriented networking approaches. PLA has been designed to scale from lightweight wireless devices to Internet core network, which is a challenge since public key cryptography operations are very resource intensive. Nevertheless, this work shows that digital signature algorithms and their hardware implementations developed for PLA are scalable to fast core network routers. Furthermore, the additional energy consumption of cryptographic operations is significantly lower than the energy cost of wireless transmission, making PLA feasible for lightweight wireless devices. Digital signature algorithms used by PLA also offer small key and signature sizes and therefore PLA's bandwidth overhead is relatively low. Strong security mechanisms offered by PLA can also be utilized for various other tasks. This work investigates how PLA can be utilized for controlling incoming connections, secure user authentication and billing, and for providing a strong accountability without an extensive data retention by network service providers

Secure and seamless prepayment for wireless mesh networks

Wireless Mesh Network (WMN) is multi-hop high-speed networking technology for broadband access. Compared to conventional network service providing systems, WMNs are easy to deploy and cost-effective. In this thesis, we propose a secure and seamless prepayment system for the Internet access through WMNs (SSPayWMN). Practical payment systems for network access generally depend on trustworthiness of service provider. However, in real life, service providers may unintentionally overcharge their clients. This misbehavior in the system may cause disputes between the clients and the service providers. Even if the service provider is rightful, it is very difficult to convince the customer since the service providers generally do not have justifiable proofs that can easily be denied by the clients. The main goal of SSPayWMN is to provide a secure payment scheme, which is fair to both operators and clients. Using cryptographic tools and techniques, all system entities are able to authenticate each other and provide/get service in an undeniable way. Moreover, SSPayWMN provides privacy and untraceability in order not to track down particular user’s network activities. We implemented SSPayWMN on a network simulator (ns-3) and performed performance evaluation to understand the latency caused by the system's protocols. Our results show that our protocols achieve low steady state latency and in overall put very little burden on the system

Identity Management and Authorization Infrastructure in Secure Mobile Access to Electronic Health Records

We live in an age of the mobile paradigm of anytime/anywhere access, as the mobile device is the most ubiquitous device that people now hold. Due to their portability, availability, easy of use, communication, access and sharing of information within various domains and areas of our daily lives, the acceptance and adoption of these devices is still growing. However, due to their potential and raising numbers, mobile devices are a growing target for attackers and, like other technologies, mobile applications are still vulnerable. Health information systems are composed with tools and software to collect, manage, analyze and process medical information (such as electronic health records and personal health records). Therefore, such systems can empower the performance and maintenance of health services, promoting availability, readability, accessibility and data sharing of vital information about a patients overall medical history, between geographic fragmented health services. Quick access to information presents a great importance in the health sector, as it accelerates work processes, resulting in better time utilization. Additionally, it may increase the quality of care. However health information systems store and manage highly sensitive data, which raises serious concerns regarding patients privacy and safety, and may explain the still increasing number of malicious incidents reports within the health domain. Data related to health information systems are highly sensitive and subject to severe legal and regulatory restrictions, that aim to protect the individual rights and privacy of patients. Along side with these legislations, security requirements must be analyzed and measures implemented. Within the necessary security requirements to access health data, secure authentication, identity management and access control are essential to provide adequate means to protect data from unauthorized accesses. However, besides the use of simple authentication models, traditional access control models are commonly based on predefined access policies and roles, and are inflexible. This results in uniform access control decisions through people, different type of devices, environments and situational conditions, and across enterprises, location and time. Although already existent models allow to ensure the needs of the health care systems, they still lack components for dynamicity and privacy protection, which leads to not have desire levels of security and to the patient not to have a full and easy control of his privacy. Within this master thesis, after a deep research and review of the stat of art, was published a novel dynamic access control model, Socio-Technical Risk-Adaptable Access Control modEl (SoTRAACE), which can model the inherent differences and security requirements that are present in this thesis. To do this, SoTRAACE aggregates attributes from various domains to help performing a risk assessment at the moment of the request. The assessment of the risk factors identified in this work is based in a Delphi Study. A set of security experts from various domains were selected, to classify the impact in the risk assessment of each attribute that SoTRAACE aggregates. SoTRAACE was integrated in an architecture with requirements well-founded, and based in the best recommendations and standards (OWASP, NIST 800-53, NIST 800-57), as well based in deep review of the state-of-art. The architecture is further targeted with the essential security analysis and the threat model. As proof of concept, the proposed access control model was implemented within the user-centric architecture, with two mobile prototypes for several types of accesses by patients and healthcare professionals, as well the web servers that handles the access requests, authentication and identity management. The proof of concept shows that the model works as expected, with transparency, assuring privacy and data control to the user without impact for user experience and interaction. It is clear that the model can be extended to other industry domains, and new levels of risks or attributes can be added because it is modular. The architecture also works as expected, assuring secure authentication with multifactor, and secure data share/access based in SoTRAACE decisions. The communication channel that SoTRAACE uses was also protected with a digital certificate. At last, the architecture was tested within different Android versions, tested with static and dynamic analysis and with tests with security tools. Future work includes the integration of health data standards and evaluating the proposed system by collecting users’ opinion after releasing the system to real world.Hoje em dia vivemos em um paradigma móvel de acesso em qualquer lugar/hora, sendo que os dispositivos móveis são a tecnologia mais presente no dia a dia da sociedade. Devido à sua portabilidade, disponibilidade, fácil manuseamento, poder de comunicação, acesso e partilha de informação referentes a várias áreas e domínios das nossas vidas, a aceitação e integração destes dispositivos é cada vez maior. No entanto, devido ao seu potencial e aumento do número de utilizadores, os dispositivos móveis são cada vez mais alvos de ataques, e tal como outras tecnologias, aplicações móveis continuam a ser vulneráveis. Sistemas de informação de saúde são compostos por ferramentas e softwares que permitem recolher, administrar, analisar e processar informação médica (tais como documentos de saúde eletrónicos). Portanto, tais sistemas podem potencializar a performance e a manutenção dos serviços de saúde, promovendo assim a disponibilidade, acessibilidade e a partilha de dados vitais referentes ao registro médico geral dos pacientes, entre serviços e instituições que estão geograficamente fragmentadas. O rápido acesso a informações médicas apresenta uma grande importância para o setor da saúde, dado que acelera os processos de trabalho, resultando assim numa melhor eficiência na utilização do tempo e recursos. Consequentemente haverá uma melhor qualidade de tratamento. Porém os sistemas de informação de saúde armazenam e manuseiam dados bastantes sensíveis, o que levanta sérias preocupações referentes à privacidade e segurança do paciente. Assim se explica o aumento de incidentes maliciosos dentro do domínio da saúde. Os dados de saúde são altamente sensíveis e são sujeitos a severas leis e restrições regulamentares, que pretendem assegurar a proteção dos direitos e privacidade dos pacientes, salvaguardando os seus dados de saúde. Juntamente com estas legislações, requerimentos de segurança devem ser analisados e medidas implementadas. Dentro dos requerimentos necessários para aceder aos dados de saúde, uma autenticação segura, gestão de identidade e controlos de acesso são essenciais para fornecer meios adequados para a proteção de dados contra acessos não autorizados. No entanto, além do uso de modelos simples de autenticação, os modelos tradicionais de controlo de acesso são normalmente baseados em políticas de acesso e cargos pré-definidos, e são inflexíveis. Isto resulta em decisões de controlo de acesso uniformes para diferentes pessoas, tipos de dispositivo, ambientes e condições situacionais, empresas, localizações e diferentes alturas no tempo. Apesar dos modelos existentes permitirem assegurar algumas necessidades dos sistemas de saúde, ainda há escassez de componentes para accesso dinâmico e proteção de privacidade , o que resultam em níveis de segurança não satisfatórios e em o paciente não ter controlo directo e total sobre a sua privacidade e documentos de saúde. Dentro desta tese de mestrado, depois da investigação e revisão intensiva do estado da arte, foi publicado um modelo inovador de controlo de acesso, chamado SoTRAACE, que molda as diferenças de acesso inerentes e requerimentos de segurança presentes nesta tese. Para isto, o SoTRAACE agrega atributos de vários ambientes e domínios que ajudam a executar uma avaliação de riscos, no momento em que os dados são requisitados. A avaliação dos fatores de risco identificados neste trabalho são baseados num estudo de Delphi. Um conjunto de peritos de segurança de vários domínios industriais foram selecionados, para classificar o impacto de cada atributo que o SoTRAACE agrega. O SoTRAACE foi integrado numa arquitectura para acesso a dados médicos, com requerimentos bem fundados, baseados nas melhores normas e recomendações (OWASP, NIST 800-53, NIST 800-57), e em revisões intensivas do estado da arte. Esta arquitectura é posteriormente alvo de uma análise de segurança e modelos de ataque. Como prova deste conceito, o modelo de controlo de acesso proposto é implementado juntamente com uma arquitetura focada no utilizador, com dois protótipos para aplicações móveis, que providênciam vários tipos de acesso de pacientes e profissionais de saúde. A arquitetura é constituída também por servidores web que tratam da gestão de dados, controlo de acesso e autenticação e gestão de identidade. O resultado final mostra que o modelo funciona como esperado, com transparência, assegurando a privacidade e o controlo de dados para o utilizador, sem ter impacto na sua interação e experiência. Consequentemente este modelo pode-se extender para outros setores industriais, e novos níveis de risco ou atributos podem ser adicionados a este mesmo, por ser modular. A arquitetura também funciona como esperado, assegurando uma autenticação segura com multi-fator, acesso e partilha de dados segura baseado em decisões do SoTRAACE. O canal de comunicação que o SoTRAACE usa foi também protegido com um certificado digital. A arquitectura foi testada em diferentes versões de Android, e foi alvo de análise estática, dinâmica e testes com ferramentas de segurança. Para trabalho futuro está planeado a integração de normas de dados de saúde e a avaliação do sistema proposto, através da recolha de opiniões de utilizadores no mundo real