Looking for Criminal Intents in JavaScript Obfuscated Code

The majority of websites incorporate JavaScript for client-side execution in a supposedly protected environment. Unfortunately, JavaScript has also proven to be a critical attack vector for both independent and state-sponsored groups of hackers. On the one hand, defenders need to analyze scripts to ensure that no threat is delivered and to respond to potential security incidents. On the other, attackers aim to obfuscate the source code in order to disorient the defenders or even to make code analysis practically impossible. Since code obfuscation may also be adopted by companies for legitimate intellectual-property protection, a dilemma remains on whether a script is harmless or malignant, if not criminal. To help analysts deal with such a dilemma, a methodology is proposed, called JACOB, which is based on five steps, namely: (1) source code parsing, (2) control flow graph recovery, (3) region identification, (4) code structuring, and (5) partial evaluation. These steps implement a sort of decompilation for control flow flattened code, which is progressively transformed into something that is close to the original JavaScript source, thereby making eventual code analysis possible. Most relevantly, JACOB has been successfully applied to uncover unwanted user tracking and fingerprinting in e-commerce websites operated by a well-known Chinese company

A two‐step authentication framework for Mobile ad hoc networks

The lack of fixed infrastructure in ad hoc networks causes nodes to rely more heavily on peer nodes for communication. Nevertheless, establishing trust in such a distributed environment is very difficult, since it is not straightforward for a node to determine if its peer nodes can be trusted. An additional concern in such an environment is with whether a peer node is merely relaying a message or if it is the originator of the message. In this paper, we propose an authentication approach for protecting nodes in mobile ad hoc networks. The security requirements for protecting data link and network layers are identified and the design criteria for creating secure ad hoc networks using several authentication protocols are analyzed. Protocols based on zero knowledge and challenge response techniques are presented and their performance is evaluated through analysis and simulation

SELINDA: a secure, scalable and light-weight data collection protocol for smart grids

Security in the smart grid is a challenge as an increasing number of sensors and measurement devices are connected to the power grid. General purpose security protocols are not suitable for providing data security to devices with limited memory, computational power and network connectivity. In this paper, we develop a secure and light-weight scalable security protocol that allows a power system operator (PO) to collect data from measurement devices (MDs) using data collectors (DCs). The security protocol trades off between computations and device memory requirements and provides flexible association between DC and MDs. These features allow data to be securely transferred from MDs to PO via mobile or untrustworthy DCs. We analyze the complexity and security of the protocol and validate its performance using experiments. Our results confirm that our proposed protocol collects data in a secure, fast and efficient manner. © 2013 IEEE.published_or_final_versio

A privacy preserving framework for cyber-physical systems and its integration in real world applications

A cyber-physical system (CPS) comprises of a network of processing and communication capable sensors and actuators that are pervasively embedded in the physical world. These intelligent computing elements achieve the tight combination and coordination between the logic processing and physical resources. It is envisioned that CPS will have great economic and societal impact, and alter the qualify of life like what Internet has done. This dissertation focuses on the privacy issues in current and future CPS applications. as thousands of the intelligent devices are deeply embedded in human societies, the system operations may potentially disclose the sensitive information if no privacy preserving mechanism is designed. This dissertation identifies data privacy and location privacy as the representatives to investigate the privacy problems in CPS. The data content privacy infringement occurs if the adversary can determine or partially determine the meaning of the transmitted data or the data stored in the storage. The location privacy, on the other hand, is the secrecy that a certain sensed object is associated to a specific location, the disclosure of which may endanger the sensed object. The location privacy may be compromised by the adversary through hop-by-hop traceback along the reverse direction of the message routing path. This dissertation proposes a public key based access control scheme to protect the data content privacy. Recent advances in efficient public key schemes, such as ECC, have already shown the feasibility to use public key schemes on low power devices including sensor motes. In this dissertation, an efficient public key security primitives, WM-ECC, has been implemented for TelosB and MICAz, the two major hardware platform in current sensor networks. WM-ECC achieves the best performance among the academic implementations. Based on WM-ECC, this dissertation has designed various security schemes, including pairwise key establishment, user access control and false data filtering mechanism, to protect the data content privacy. The experiments presented in this dissertation have shown that the proposed schemes are practical for real world applications. to protect the location privacy, this dissertation has considered two adversary models. For the first model in which an adversary has limited radio detection capability, the privacy-aware routing schemes are designed to slow down the adversary\u27s traceback progress. Through theoretical analysis, this dissertation shows how to maximize the adversary\u27s traceback time given a power consumption budget for message routing. Based on the theoretical results, this dissertation also proposes a simple and practical weighted random stride (WRS) routing scheme. The second model assumes a more powerful adversary that is able to monitor all radio communications in the network. This dissertation proposes a random schedule scheme in which each node transmits at a certain time slot in a period so that the adversary would not be able to profile the difference in communication patterns among all the nodes. Finally, this dissertation integrates the proposed privacy preserving framework into Snoogle, a sensor nodes based search engine for the physical world. Snoogle allows people to search for the physical objects in their vicinity. The previously proposed privacy preserving schemes are applied in the application to achieve the flexible and resilient privacy preserving capabilities. In addition to security and privacy, Snoogle also incorporates a number of energy saving and communication compression techniques that are carefully designed for systems composed of low-cost, low-power embedded devices. The evaluation study comprises of the real world experiments on a prototype Snoogle system and the scalability simulations

Secure key design approaches using entropy harvesting in wireless sensor network: A survey

Physical layer based security design in wireless sensor networks have gained much importance since the past decade. The various constraints associated with such networks coupled with other factors such as their deployment mainly in remote areas, nature of communication etc. are responsible for development of research works where the focus is secured key generation, extraction, and sharing. Keeping the importance of such works in mind, this survey is undertaken that provides a vivid description of the different mechanisms adopted for securely generating the key as well its randomness extraction and also sharing. This survey work not only concentrates on the more common methods, like received signal strength based but also goes on to describe other uncommon strategies such as accelerometer based. We first discuss the three fundamental steps viz. randomness extraction, key generation and sharing and their importance in physical layer based security design. We then review existing secure key generation, extraction, and sharing mechanisms and also discuss their pros and cons. In addition, we present a comprehensive comparative study of the recent advancements in secure key generation, sharing, and randomness extraction approaches on the basis of adversary, secret bit generation rate, energy efficiency etc. Finally, the survey wraps up with some promising future research directions in this area

Encriptação parcialmente homomórfica CCA1-segura

Orientadores: Ricardo Dahab, Diego de Freitas AranhaTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Nesta tese nosso tema de pesquisa é a encriptação homomórfica, com foco em uma solução prática e segura para encriptação parcialmente homomórfica (somewhat homomorphic encryption - SHE), considerando o modelo de segurança conhecido como ataque de texto encriptado escolhido (chosen ciphertext attack - CCA). Este modelo pode ser subdividido em duas categorias, a saber, CCA1 e CCA2, sendo CCA2 o mais forte. Sabe-se que é impossível construir métodos de encriptação homomórfica que sejam CCA2-seguros. Por outro lado, é possível obter segurança CCA1, mas apenas um esquema foi proposto até hoje na literatura; assim, seria interessante haver outras construções oferecendo este tipo de segurança. Resumimos os principais resultados desta tese de doutorado em duas contribuições. A primeira é mostrar que a família NTRU de esquemas SHE é vulnerável a ataques de recuperação de chave privada, e portanto não são CCA1-seguros. A segunda é a utilização de computação verificável para obter esquemas SHE que são CCA1-seguros e que podem ser usados para avaliar polinômios multivariáveis quadráticos. Atualmente, métodos de encriptação homomórfica são construídos usando como substrato dois problemas de difícil solução: o MDC aproximado (approximate GCD problem - AGCD) e o problema de aprendizado com erros (learning with errors - LWE). O problema AGCD leva, em geral, a construções mais simples mas com desempenho inferior, enquanto que os esquemas baseados no problema LWE correspondem ao estado da arte nesta área de pesquisa. Recentemente, Cheon e Stehlé demonstraram que ambos problemas estão relacionados, e é uma questão interessante investigar se esquemas baseados no problema AGCD podem ser tão eficientes quanto esquemas baseados no problema LWE. Nós respondemos afirmativamente a esta questão para um cenário específico: estendemos o esquema de computação verificável proposto por Fiore, Gennaro e Pastro, de forma que use a suposição de que o problema AGCD é difícil, juntamente com o esquema DGHV adaptado para uso do Teorema Chinês dos Restos (Chinese remainder theorem - CRT) de forma a evitar ataques de recuperação de chave privadaAbstract: In this thesis we study homomorphic encryption with focus on practical and secure somewhat homomorphic encryption (SHE), under the chosen ciphertext attack (CCA) security model. This model is classified into two different main categories: CCA1 and CCA2, with CCA2 being the strongest. It is known that it is impossible to construct CCA2-secure homomorphic encryption schemes. On the other hand, CCA1-security is possible, but only one scheme is known to achieve it. It would thus be interesting to have other CCA1-secure constructions. The main results of this thesis are summarized in two contributions. The first is to show that the NTRU-family of SHE schemes is vulnerable to key recovery attacks, hence not CCA1-secure. The second is the utilization of verifiable computation to obtain a CCA1-secure SHE scheme that can be used to evaluate quadratic multivariate polynomials. Homomorphic encryption schemes are usually constructed under the assumption that two distinct problems are hard, namely the Approximate GCD (AGCD) Problem and the Learning with Errors (LWE) Problem. The AGCD problem leads, in general, to simpler constructions, but with worse performance, wheras LWE-based schemes correspond to the state-of-the-art in this research area. Recently, Cheon and Stehlé proved that both problems are related, and thus it is an interesting problem to investigate if AGCD-based SHE schemes can be made as efficient as their LWE counterparts. We answer this question positively for a specific scenario, extending the verifiable computation scheme proposed by Fiore, Gennaro and Pastro to work under the AGCD assumption, and using it together with the Chinese Remainder Theorem (CRT)-version of the DGHV scheme, in order to avoid key recovery attacksDoutoradoCiência da ComputaçãoDoutor em Ciência da Computação143484/2011-7CNPQCAPE

User-differentiated hierarchical key management for the bring-your-own-device environments

To ensure confidentiality, the sensitive electronic data held within a corporation is always carefully encrypted and stored in a manner so that it is inaccessible to those parties who are not involved. During this process, the specific manners of how to keep, distribute, use, and update keys which are used to encrypt the sensitive data become an important thing to be considered. Through use of hierarchical key management, a technique that provides access controls in multi-user systems where a portion of sensitive resources shall only be made available to authorized users or security ordinances, required information is distributed on a need-to-know basis. As a result of this hierarchical key management, time-bound hierarchical key management further adds time controls to the information access process. There is no existing hierarchical key management scheme or time-bound hierarchical key management scheme which is able to differentiate users with the same authority. When changes are required for any user, all other users who have the same access authorities will be similarly affected, and this deficiency then further deteriorates due to a recent trend which has been called Bring-Your-Own-Device. This thesis proposes the construction of a new time-bound hierarchical key management scheme called the User-Differentiated Two-Layer Encryption-Based Scheme (UDTLEBC), one which is designed to differentiate between users. With this differentiation, whenever any changes are required for one user during the processes of key management, no additional users will be affected during these changes and these changes can be done without interactions with the users. This new scheme is both proven to be secure as a time-bound hierarchical key management scheme and efficient for use in a BYOD environment