@article {AlcarazLopezWolthusen2017, title = {OCPP Protocol: Security Threats and Challenges}, journal = {IEEE Transactions on Smart Grid}, volume = {8}, year = {2017}, month = {02/2017}, pages = {2452 - 2459}, publisher = {IEEE}, abstract = {

One benefit postulated for the adoption of Electric Vehicles (EVs) is their\ ability to act as stabilizing entities in smart grids through bi-directional charging,\ allowing local or global smoothing of peaks and imbalances. This benefit,\ however, hinges indirectly on the reliability and security of the power flows\ thus achieved. Therefore this paper studies key security properties of the alreadydeployed\ Open Charge Point Protocol (OCPP) specifying communication between\ charging points and energy management systems. It is argued that possible subversion\ or malicious endpoints in the protocol can also lead to destabilization of\ power networks. Whilst reviewing these aspects, we focus, from a theoretical and\ practical standpoint, on attacks that interfere with resource reservation originating\ with the EV, which may also be initiated by a man in the middle, energy theft or\ fraud. Such attacks may even be replicated widely, resulting in over- or undershooting\ of power network provisioning, or the (total/partial) disintegration of the\ integrity and stability of power networks.

}, keywords = {Charging Infrastructure, Cyber Security, Cyber- Physical Systems, OCPP, Smart Grid}, issn = {1949-3053 }, doi = {https://doi.org/10.1109/TSG.2017.2669647}, author = {Cristina Alcaraz and Javier Lopez and Stephen Wolthunsen} } @article {alcaraz2016POL, title = {Policy Enforcement System for Secure Interoperable Control in Distributed Smart Grid Systems}, journal = {Journal of Network and Computer Applications}, volume = {59}, year = {2016}, month = {01/2016}, pages = {301{\textendash}314}, publisher = {Elsevier}, abstract = {

Interoperability of distributed systems in charge of monitoring and maintaining the different critical domains belonging to Smart Grid scenarios comprise the central topic of this paper. Transparency in control transactions under a secure and reliable architecture is the aim of the policy enforcement system proposed here. The approach is based on the degree of observation of a context and on the role-based access control model defined by the IEC-62351-8 standard. Only authenticated and authorised entities are able to take control of those distributed elements (e.g., IEC-61850 objects) located at distant geographical locations and close to the critical infrastructures (e.g., substations). To ensure the effectiveness of the approach, it is built on graphical-theoretical formulations corresponding to graph theory, where it is possible to illustrate power control networks through power-law distributions whose monitoring relies on structural controllability theory. The interconnection of these distributions is subject to a network architecture based on the concept of the supernode where the interoperability depends on a simple rule-based expert system. This expert system focuses not only on accepting or denying access, but also on providing the means to attend to extreme situations, avoiding, as much as possible, the overloading of the communication. Through one practical study we also show the functionalities of the approach and the benefits that the authorisation itself can bring to the interoperability.\ 

}, issn = {1084-8045}, author = {Cristina Alcaraz and Javier Lopez and Stephen Wolthusen} } @inproceedings {alcaraz2013controla, title = {Multi-Round Attacks on Structural Controllability Properties for Non-Complete Random Graphs}, booktitle = {The 16th Information Security Conference (ISC)}, volume = {7807}, year = {2015}, month = {09/2015}, pages = {140{\textendash}151}, publisher = {Springer}, organization = {Springer}, address = {Springer International Publishing Switzerland}, abstract = {

\ The notion of controllability, informally the ability to force a system\ into a desired state in a finite time or number of steps, is most closely associated with control systems such as those used to maintain power networks and other critical infrastructures, but has wider relevance in distributed systems. It is clearly highly desirable to understand under which conditions attackers may be able to disrupt legitimate control, or to force overriding controllability themselves. Following recent results by Liu et al., there has been considerable interest also in graph-theoretical interpretation of Kalman controllability originally introduced by Lin, structural controllability. This permits the identification of sets of driver nodes with the desired state-forcing property, but determining such nodes\ is aW[2]-hard problem. To extract these nodes and represent the control relation, here we apply the POWER DOMINATING SET problem and investigate the effects of targeted iterative multiple-vertex removal. We report the impact that different attack strategies with multiple edge and vertex removal will have, based on underlying non-complete graphs, with an emphasis on power-law random graphs with different degree sequences.

}, doi = {10.1007/978-3-319-27659-5 10}, author = {Cristina Alcaraz and Estefania Etcheves Miciolino and Stephen Wolthusen} } @inproceedings {430, title = {Recovery of Structural Controllability for Control Systems}, booktitle = {Eighth IFIP WG 11.10 International Conference on Critical Infrastructure Protection, SRI International, Arlington, Virginia, USA }, volume = {441}, year = {2014}, pages = {47-63}, publisher = {Springer}, organization = {Springer}, address = {Arlington, Virginia, USA}, abstract = {

Fundamental problems in control systems theory are controllability and observability, and designing control systems so that these properties are satisfied or approximated sufficiently. However, it is prudent to as- sume that an attacker will not only be able to subvert measurements but also control the system. Moreover, an advanced adversary with an understanding of the control system may seek to take over control of the entire system or parts thereof, or deny the legitimate operator this capability. The effectiveness of such attacks has been demonstrated in previous work. Indeed, these attacks cannot be ruled out given the likely existence of unknown vulnerabilities, increasing connectivity of nominally air-gapped systems and supply chain issues. The ability to rapidly recover control after an attack has been initiated and to detect an adversary{\textquoteright}s presence is, therefore, critical. This paper focuses on the problem of structural controllability, which has recently attracted substantial attention through the equivalent problem of the power dom- inating set introduced in the context of electrical power network control. However, these problems are known to be NP-hard with poor approx- imability. Given their relevance to many networks, especially power networks, this paper studies strategies for the efficient restoration of controllability following attacks and attacker-defender interactions in power-law networks.\ 

}, keywords = {Control systems, power domination, resilience, structural controllability}, isbn = {978-3-662-45354-4}, issn = {1868-4238}, doi = {http://dx.doi.org/10.1007/978-3-662-45355-1_4}, author = {Cristina Alcaraz and Stephen Wolthusen} } @inproceedings {1810, title = {Structural Controllability of Networks for Non-Interactive Adversarial Vertex Removal}, booktitle = {8th International Conference on Critical Information Infrastructures Security}, volume = {8328}, year = {2013}, pages = {120-132}, publisher = {Springer}, organization = {Springer}, address = {Amsterdam, The Netherlands}, abstract = {

The problem of controllability of networks arises in a number of different\ domains, including in critical infrastructure systems where control must be\ maintained continuously. Recent work by Liu et al. has renewed interest in the\ seminal work by Lin on structural controllability, providing a graph-theoretical\ interpretation. This allows the identification of driver nodes capable of forcing the\ system into a desired state, which implies an obvious target for attackers wishing\ to disrupt the network control. Several methods for identifying driver nodes\ exist, but require undesirable computational complexity. In this paper, we therefore\ investigate the ability to regain or maintain controllability in the presence\ of adversaries able to remove vertices and implicit edges of the controllability\ graph. For this we rely on the POWER DOMINATING SET (PDS) formulation for\ identifying the control structure and study different attack strategies for multiple\ network models. As the construction of a PDS for a given graph is not unique,\ we further investigate different strategies for PDS construction, and provide a\ simulative evaluation.

}, issn = {0302-9743}, doi = {http://link.springer.com/chapter/10.1007\%2F978-3-319-03964-0_11}, author = {Cristina Alcaraz and Estefania Etcheves Miciolino and Stephen Wolthusen} } @incollection {BC2011Alcaraz, title = {Security Aspects of SCADA and DCS Environments}, booktitle = {Critical Infrastructure Protection: Information Infrastructure Models, Analysis, and Defense}, series = {Advances in Critical Infrastructure Protection: Information Infrastructure Models, Analysis, and Defense. LNCS 7130.}, volume = {7130}, year = {2012}, month = {September 2012}, pages = {120-149}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Heidelberger (Berlin, Alemania)}, abstract = {

SCADA Systems can be seen as a fundamental component in Critical Infrastructures, having an impact in the overall performance of other Critical Infrastructures interconnected. Currently, these systems include in their network designs different types of Information and Communication Technology systems (such as the Internet and wireless technologies), not only to modernize operational processes but also to ensure automation and real-time control. Nonetheless, the use of these new technologies will bring new security challenges, which will have a significant impact on both the business process and home users. Therefore, the main purpose of this Chapter is to address these issues and to analyze the interdependencies of Process Control Systems with ICT systems, to discuss some security aspects and to offer some possible solutions and recommendations.

}, keywords = {Critical Information Infrastructure Protection, SCADA Systems}, isbn = {ISBN:978-3-642-28919-4}, issn = {0302-9743}, author = {Cristina Alcaraz and Gerardo Fernandez and Fernando Carvajal}, editor = {Javier Lopez and Stephen. Wolthunsen and Roberto Setola} }