Biblio
Blockchain-based cryptocurrencies offer an appealing alternative to Fiat currencies, due to their decentralized and borderless nature. However the decentralized settings make the authentication process more challenging: Standard cryptographic methods often rely on the ability of users to reliably store a (large) secret information. What happens if one user's key is lost or stolen? Blockchain systems lack of fallback mechanisms that allow one to recover from such an event, whereas the traditional banking system has developed and deploys quite effective solutions. In this work, we develop new cryptographic techniques to integrate security policies (developed in the traditional banking domain) in the blockchain settings. We propose a system where a smart contract is given the custody of the user's funds and has the ability to invoke a two-factor authentication (2FA) procedure in case of an exceptional event (e.g., a particularly large transaction or a key recovery request). To enable this, the owner of the account secret-shares the answers of some security questions among a committee of users. When the 2FA mechanism is triggered, the committee members can provide the smart contract with enough information to check whether an attempt was successful, and nothing more. We then design a protocol that securely and efficiently implements such a functionality: The protocol is round-optimal, is robust to the corruption of a subset of committee members, supports low-entropy secrets, and is concretely efficient. As a stepping stone towards the design of this protocol, we introduce a new threshold homomorphic encryption scheme for linear predicates from bilinear maps, which might be of independent interest. To substantiate the practicality of our approach, we implement the above protocol as a smart contract in Ethereum and show that it can be used today as an additional safeguard for suspicious transactions, at minimal added cost. We also implement a second scheme where the smart contract additionally requests a signature from a physical hardware token, whose verification key is registered upfront by the owner of the funds. We show how to integrate the widely used universal two-factor authentication (U2F) tokens in blockchain environments, thus enabling the deployment of our system with available hardware.
Cyber security risk assessment is very important to quantify the security level of communication-based train control (CBTC) systems. In this paper, a methodology is proposed to assess the cyber security risk of CBTC systems that integrates complex network theory and attack graph method. On one hand, in order to determine the impact of malicious attacks on train control, we analyze the connectivity of movement authority (MA) paths based on the working state of nodes, the connectivity of edges. On the other hand, attack graph is introduced to quantify the probabilities of potential attacks that combine multiple vulnerabilities in the cyber world of CBTC. Experiments show that our methodology can assess the security risks of CBTC systems and improve the security level after implementing reinforcement schemes.
Cyber-physical systems are vulnerable to attacks that can cause them to reach undesirable states. This paper provides a theoretical solution for increasing the resiliency of control systems through the use of a high-authority supervisor that monitors and regulates control signals sent to the actuator. The supervisor aims to determine the control signal limits that provide maximum freedom of operation while protecting the system. For this work, a cyber attack is assumed to overwrite the signal to the actuator with Gaussian noise. This assumption permits the propagation of a state covariance matrix through time. Projecting the state covariance matrix on the state space reveals a confidence ellipse that approximates the reachable set. The standard deviation is found so that the confidence ellipse is tangential to the danger area in the state space. The process is applied to ship dynamics where an ellipse in the state space is transformed to an arc in the plane of motion. The technique is validated through the simulation of a ship traveling through a narrow channel while under the influence of a cyber attack.
with the continuous growing threat of cyber terrorism, the vulnerability of the industrial control systems (ICS) is the most common subject for security researchers now. Attacks on ICS systems keep increasing and their impact leads to human safety issues, equipment damage, system down, unusual output, loss of visibility and control, and various other catastrophic failures. Many of the industrial control systems are relatively insecure with chronic and pervasive vulnerabilities. Modbus-Tcpis one of the widely used communication protocols in the ICS/ Supervisory control and data acquisition (SCADA) system to transmit signals from instrumentation and control devices to the main controller of the control center. Modbus is a plain text protocol without any built-in security mechanisms, and Modbus is a standard communication protocol, widely used in critical infrastructure applications such as power systems, water, oil & gas, etc.. This paper proposes a passive security solution called Deep-security-scanner (DSS) tailored to Modbus-Tcpcommunication based Industrial control system (ICS). DSS solution detects attacks on Modbus-TcpIcs networks in a passive manner without disturbing the availability requirements of the system.
Discovering vulnerabilities is an information-intensive task that requires a developer to locate the defects in the code that have security implications. The task is difficult due to the growing code complexity and some developer's lack of security expertise. Although tools have been created to ease the difficulty, no single one is sufficient. In practice, developers often use a combination of tools to uncover vulnerabilities. Yet, the basis on which different tools are composed is under explored. In this paper, we examine the composition base by taking advantage of the tool design patterns informed by foraging theory. We follow a design science methodology and carry out a three-step empirical study: mapping 34 foraging-theoretic patterns in a specific vulnerability discovery tool, formulating hypotheses about the value and cost of foraging when considering two composition scenarios, and performing a human-subject study to test the hypotheses. Our work offers insights into guiding developers' tool usage in detecting software vulnerabilities.