Biblio

Cyber-physical systems (CPS) are often network integrated to enable remote management, monitoring, and reporting. Such integration has made them vulnerable to cyber attacks originating from an untrusted network (e.g., the internet). Once an attacker breaches the network security, he could corrupt operations of the system in question, which may in turn lead to catastrophes. Hence there is a critical need to detect intrusions into mission-critical CPS. Signature based detection may not work well for CPS, whose complexity may preclude any succinct signatures that we will need. Specification based detection requires accurate definitions of system behaviour that similarly can be hard to obtain, due to the CPS's complexity and dynamics, as well as inaccuracies and incompleteness of design documents or operation manuals. Formal models, to be tractable, are often oversimplified, in which case they will not support effective detection. In this paper, we study a behaviour-based machine learning (ML) approach for the intrusion detection. Whereas prior unsupervised ML methods have suffered from high missed detection or false-positive rates, we use a high-fidelity CPS testbed, which replicates all main physical and control components of a modern water treatment facility, to generate systematic training data for a supervised method. The method does not only detect the occurrence of a cyber attack at the physical process layer, but it also identifies the specific type of the attack. Its detection is fast and robust to noise. Furthermore, its adaptive system model can learn quickly to match dynamics of the CPS and its operating environment. It exhibits a low false positive (FP) rate, yet high precision and recall.

This paper describes an approach for detecting the presence of domain name system (DNS) tunnels in network traffic. DNS tunneling is a common technique hackers use to establish command and control nodes and to exfiltrate data from networks. To generate the training data sufficient to build models to detect DNS tunneling activity, a penetration testing effort was employed. We extracted features from this data and trained random forest classifiers to distinguish normal DNS activity from tunneling activity. The classifiers successfully detected the presence of tunnels we trained on, and four other types of tunnels that were not a part of the training set.

Intrusion detection using multiple security devices has received much attention recently. The large volume of information generated by these tools, however, increases the burden on both computing resources and security administrators. Moreover, attack detection does not improve as expected if these tools work without any coordination. In this work, we propose a simple method to join information generated by security monitors with diverse data formats. We present a novel intrusion detection technique that uses unsupervised clustering algorithms to identify malicious behavior within large volumes of diverse security monitor data. First, we extract a set of features from network-level and host-level security logs that aid in detecting malicious host behavior and flooding-based network attacks in an enterprise network system. We then apply clustering algorithms to the separate and joined logs and use statistical tools to identify anomalous usage behaviors captured by the logs. We evaluate our approach on an enterprise network data set, which contains network and host activity logs. Our approach correctly identifies and prioritizes anomalous behaviors in the logs by their likelihood of maliciousness. By combining network and host logs, we are able to detect malicious behavior that cannot be detected by either log alone.

Obfuscation is a mechanism used to hinder reverse engineering of programs. To cope with the large number of obfuscated programs, especially malware, reverse engineers automate the process of deobfuscation i.e. extracting information from obfuscated programs. Deobfuscation techniques target specific obfuscation transformations, which requires reverse engineers to manually identify the transformations used by a program, in what is known as metadata recovery attack. In this paper, we present Oedipus, a Python framework that uses machine learning classifiers viz., decision trees and naive Bayes, to automate metadata recovery attacks against obfuscated programs. We evaluated Oedipus' performance using two datasets totaling 1960 unobfuscated C programs, which were used to generate 11.075 programs obfuscated using 30 configurations of 6 different obfuscation transformations. Our results empirically show the feasibility of using machine learning to implement the metadata recovery attacks with classification accuracies of 100% in some cases.

Large scale datacenters are becoming the compute and data platform of large enterprises, but their scale makes them difficult to secure applications running within. We motivate this setting using a real world complex scenario, and propose a data-driven approach to taming this complexity. We discuss several machine learning problems that arise, in particular focusing on inducing so-called whitelist communication policies, from observing masses of communications among networked computing nodes. Briefly, a whitelist policy specifies which machine, or groups of machines, can talk to which. We present some of the challenges and opportunities, such as noisy and incomplete data, non-stationarity, lack of supervision, challenges of evaluation, and describe some of the approaches we have found promising.

The ubiquity of portable mobile devices equipped with built-in cameras have led to a transformation in how and when digital images are captured, shared, and archived. Photographs and videos from social gatherings, public events, and even crime scenes are commonplace online. While the spontaneity afforded by these devices have led to new personal and creative outlets, privacy concerns of bystanders (and indeed, in some cases, unwilling subjects) have remained largely unaddressed. We present I-Pic, a trusted software platform that integrates digital capture with user-defined privacy. In I-Pic, users choose alevel of privacy (e.g., image capture allowed or not) based upon social context (e.g., out in public vs. with friends vs. at workplace). Privacy choices of nearby users are advertised via short-range radio, and I-Pic-compliant capture platforms generate edited media to conform to privacy choices of image subjects. I-Pic uses secure multiparty computation to ensure that users' visual features and privacy choices are not revealed publicly, regardless of whether they are the subjects of an image capture. Just as importantly, I-Pic preserves the ease-of-use and spontaneous nature of capture and sharing between trusted users. Our evaluation of I-Pic shows that a practical, energy-efficient system that conforms to the privacy choices of many users within a scene can be built and deployed using current hardware.

Network protocols such as Ethernet and TCP/IP were not designed to ensure the security and privacy of users. To protect users' privacy, anonymity networks such as Tor have been proposed to hide both identities and communication contents for Internet traffic. However, such solutions cannot protect enterprise network traffic that does not transit the Internet. In this paper, we present the design, implementation, and evaluation of a moving target technique called Packet Header Randomization (PHEAR), a privacy-enhancing system for enterprise networks that leverages emerging Software-Defined Networking hardware and protocols to eliminate identifiers found at the MAC, Network, and higher layers of the network stack. PHEAR also encrypts all packet data beyond the Network layer. We evaluate the security of PHEAR against a variety of known and novel attacks and conduct whole-network experiments that show the prototype deployment provides sufficient performance for common applications such as web browsing and file sharing.

Digital signatures are perhaps the most important base for authentication and trust relationships in large scale systems. More specifically, various applications of signatures provide privacy and anonymity preserving mechanisms and protocols, and these, in turn, are becoming critical (due to the recently recognized need to protect individuals according to national rules and regulations). A specific type of signatures called "signatures with efficient protocols", as introduced by Camenisch and Lysyanskaya (CL), efficiently accommodates various basic protocols and extensions like zero-knowledge proofs, signing committed messages, or re-randomizability. These are, in fact, typical operations associated with signatures used in typical anonymity and privacy-preserving scenarios. To date there are no "signatures with efficient protocols" which are based on simple assumptions and truly practical. These two properties assure us a robust primitive: First, simple assumptions are needed for ensuring that this basic primitive is mathematically robust and does not require special ad hoc assumptions that are more risky, imply less efficiency, are more tuned to the protocol itself, and are perhaps less trusted. In the other dimension, efficiency is a must given the anonymity applications of the protocol, since without proper level of efficiency the future adoption of the primitives is always questionable (in spite of their need). In this work, we present a new CL-type signature scheme that is re-randomizable under a simple, well-studied, and by now standard, assumption (SXDH). The signature is efficient (built on the recent QA-NIZK constructions), and is, by design, suitable to work in extended contexts that typify privacy settings (like anonymous credentials, group signature, and offline e-cash). We demonstrate its power by presenting practical protocols based on it.

Explicit non-linear transformations of existing steganalysis features are shown to boost their ability to detect steganography in combination with existing simple classifiers, such as the FLD-ensemble. The non-linear transformations are learned from a small number of cover features using Nyström approximation on pilot vectors obtained with kernelized PCA. The best performance is achieved with the exponential form of the Hellinger kernel, which improves the detection accuracy by up to 2-3% for spatial-domain contentadaptive steganography. Since the non-linear map depends only on the cover source and its learning has a low computational complexity, the proposed approach is a practical and low cost method for boosting the accuracy of existing detectors built as binary classifiers. The map can also be used to significantly reduce the feature dimensionality (by up to factor of ten) without performance loss with respect to the non-transformed features.

The safety of information inside of cloud networks is of interest to the network administrators. In a new insider attack, inside attackers merge confidential information with videos using digital video steganography. The video can be uploaded to video websites, where the information can be distributed online, where it can cost firms millions in damages. Standard behavior based exfiltration detection does not always prevent these attacks. This form of steganography is almost invisible. Existing compressed video steganalysis only detects small-payload watermarks. We develop such a strategy using distributed algorithms and classify videos, then compare existing algorithms to new ones. We find our approach improves on behavior based exfiltration detection, and on the existing online video steganalysis.

Chang-Chen-Wang's (3,n) Secret grayscale image Sharing between n grayscale cover images method with participant Authentication and damaged pixels Repairing (SSAR) properties is analyzed; it restores the secret image from any three of the cover images used. We show that SSAR may fail, is not able fake participant recognizing, and has limited by 62.5% repairing ability. We propose SSAR (4,n) enhancement, SSAR-E, allowing 100% exact restoration of a corrupted pixel using any four of n covers, and recognizing a fake participant with the help of cryptographic hash functions with 5-bit values that allows better (vs. 4 bits) error detection. Using a special permutation with only one loop including all the secret image pixels, SSAR-E is able restoring all the secret image damaged pixels having just one correct pixel left. SSAR-E allows restoring the secret image to authorized parties only contrary to SSAR. The performance and size of cover images for SSAR-E are the same as for SSAR.

Steganography enables user to hide confidential data in any digital medium such that its existence cannot be concealed by the third party. Several research work is being is conducted to improve steganography algorithm's efficiency. Recent trends in computing technology use steganography as an important tool for hiding confidential data. This paper summarizes some of the research work conducted in the field of image steganography in spatial domain along with their advantages and disadvantages. Future research work and experimental results of some techniques is also being discussed. The key goal is to show the powerful impact of steganography in information hiding and image processing domain.

This article deals with color images steganalysis based on machine learning. The proposed approach enriches the features from the Color Rich Model by adding new features obtained by applying steerable Gaussian filters and then computing the co-occurrence of pixel pairs. Adding these new features to those obtained from Color-Rich Models allows us to increase the detectability of hidden messages in color images. The Gaussian filters are angled in different directions to precisely compute the tangent of the gradient vector. Then, the gradient magnitude and the derivative of this tangent direction are estimated. This refined method of estimation enables us to unearth the minor changes that have occurred in the image when a message is embedded. The efficiency of the proposed framework is demonstrated on three stenographic algorithms designed to hide messages in images: S-UNIWARD, WOW, and Synch-HILL. Each algorithm is tested using different payload sizes. The proposed approach is compared to three color image steganalysis methods based on computation features and Ensemble Classifier classification: the Spatial Color Rich Model, the CFA-aware Rich Model and the RGB Geometric Color Rich Model.

The MP4 files has become to most used video media file available, and will mostly likely remain at the top for some time to come. This makes MP4 files an interesting candidate for steganography. With its size and structure, it offers a challenge to steganography developers. While some attempts have been made to create a truly covert file, few are as successful as Martin Fiedler's TCSteg. TCSteg allows users to hide a TrueCrypt hidden volume in an MP4 file. The structure of the file makes it difficult to identify that a volume exists. In our analysis of TCSteg, we will show how Fielder's code works and how we may be able to detect the existence of steganography. We will then implement these methods in hope that other steganography analysis can use them to determine if an MP4 file is a carrier file. Finally, we will address the future of MP4 steganography.

Steganography is the science of hiding data within data. Either for the good purpose of secret communication or for the bad intention of leaking sensitive confidential data or embedding malicious code or URL. However, many different carrier file formats can be used to hide these data (network, audio, image..etc) but the most common steganography carrier is embedding secret data within images as it is considered to be the best and easiest way to hide all types of files (secret files) within an image using different formats (another image, text, video, virus, URL..etc). To the human eye, the changes in the image appearance with the hidden data can be imperceptible. In fact, images can be more than what we see with our eyes. Therefore, many solutions where proposed to help in detecting these hidden data but each solution have their own strong and weak points either by the limitation of resolving one type of image along with specific hiding technique and or most likely without extracting the hidden data. This paper intends to propose a novel detection approach that will concentrate on detecting any kind of hidden URL in all types of images and extract the hidden URL from the carrier image that used the LSB least significant bit hiding technique.

Recommendation systems become popular in our daily life. It is well known that the more the release of users' personal data, the better the quality of recommendation. However, such services raise serious privacy concerns for users. In this paper, focusing on matrix factorization-based recommendation systems, we propose the first privacy-preserving matrix factorization using fully homomorphic encryption. On inputs of encrypted users' ratings, our protocol performs matrix factorization over the encrypted data and returns encrypted outputs so that the recommendation system knows nothing on rating values and resulting user/item profiles. It provides a way to obfuscate the number and list of items a user rated without harming the accuracy of recommendation, and additionally protects recommender's tuning parameters for business benefit and allows the recommender to optimize the parameters for quality of service. To overcome performance degradation caused by the use of fully homomorphic encryption, we introduce a novel data structure to perform computations over encrypted vectors, which are essential operations for matrix factorization, through secure 2-party computation in part. With the data structure, the proposed protocol requires dozens of times less computation cost over those of previous works. Our experiments on a personal computer with 3.4 GHz 6-cores 64 GB RAM show that the proposed protocol runs in 1.5 minutes per iteration. It is more efficient than Nikolaenko et al.'s work proposed in CCS 2013, in which it took about 170 minutes on two servers with 1.9 GHz 16-cores 128 GB RAM.

Cloud computing is rapidly reshaping the server administration landscape. The widespread use of virtualization and the increasingly high server consolidation ratios, in particular, have introduced unprecedented security challenges for users, increasing the exposure to intrusions and opening up new opportunities for attacks. Deploying security mechanisms in the hypervisor to detect and stop intrusion attempts is a promising strategy to address this problem. Existing hypervisor-based solutions, however, are typically limited to very specific classes of attacks and introduce exceedingly high performance overhead for production use. In this paper, we present Slick (Storage-Level Intrusion ChecKer), an intrusion detection system (IDS) for virtualized storage devices. Slick detects intrusion attempts by efficiently and transparently monitoring write accesses to critical regions on storage devices. The low-overhead monitoring component operates entirely inside the hypervisor, with no introspection or modifications required in the guest VMs. Using Slick, users can deploy generic IDS rules to detect a broad range of real-world intrusions in a flexible and practical way. Experimental results confirm that Slick is effective at enhancing the security of virtualized servers, while imposing less than 5% overhead in production.

Embedded virtualization has emerged as a valuable way to reduce costs, improve software quality, and decrease design time. Additionally, virtualization can enforce the overall system's security from several perspectives. One is security due to separation, where the hypervisor ensures that one domain does not compromise the execution of other domains. At the same time, the advances in the development of IoT applications opened discussions about the security flaws that were introduced by IoT devices. In a few years, billions of these devices will be connected to the cloud exchanging information. This is an opportunity for hackers to exploit their vulnerabilities, endangering applications connected to such devices. At this point, it is inevitable to consider virtualization as a possible approach for IoT security. In this paper we discuss how embedded virtualization could take place on IoT devices as a sound solution for security.

Cloud service providers typically adopt the multi-tenancy model to optimize resources usage and achieve the promised cost-effectiveness. Sharing resources between different tenants and the underlying complex technology increase the necessity of transparency and accountability. In this regard, auditing security compliance of the provider's infrastructure against standards, regulations and customers' policies takes on an increasing importance in the cloud to boost the trust between the stakeholders. However, virtualization and scalability make compliance verification challenging. In this work, we propose an automated framework that allows auditing the cloud infrastructure from the structural point of view while focusing on virtualization-related security properties and consistency between multiple control layers. Furthermore, to show the feasibility of our approach, we integrate our auditing system into OpenStack, one of the most used cloud infrastructure management systems. To show the scalability and validity of our framework, we present our experimental results on assessing several properties related to auditing inter-layer consistency, virtual machines co-residence, and virtual resources isolation.

This paper presents SplitBox, an efficient system for privacy-preserving processing of network functions that are outsourced as software processes to the cloud. Specifically, cloud providers processing the network functions do not learn the network policies instructing how the functions are to be processed. First, we propose an abstract model of a generic network function based on match-action pairs. We assume that this function is processed in a distributed manner by multiple honest-but-curious cloud service providers. Then, we introduce our SplitBox system for private network function virtualization and present a proof-of-concept implementation on FastClick, an extension of the Click modular router, using a firewall as a use case. Our experimental results achieve a throughput of over 2 Gbps with 1 kB-sized packets on average, traversing up to 60 firewall rules.

Network monitoring is vital to the administration and operation of networks, but it requires privileged access that only highly trusted parties are granted. This severely limits the opportunity for external parties, such as service or equipment providers, auditors, or even clients, to measure the health or operation of a network in which they are stakeholders, but do not have access to its internal structure. In this position paper we propose the use of middleboxes to open up network monitoring to external parties using privacy-preserving technology. This will allow distrusted parties to make more inferences about the network state than currently possible, without learning any precise information about the network or the data that crosses it. Thus the state of the network will be more transparent to external stakeholders, who will be empowered to verify claims made by network operators. Network operators will be able to provide more information about their network without compromising security or privacy.

This paper describes an approach where group testing helps in enforcing security and privacy in identification. We detail a particular scheme based on embedding and group testing. We add a second layer of defense, group vectors, where each group vector represents a set of dataset vectors. Whereas the selected embedding poorly protects the data when used alone, the group testing approach makes it much harder to reconstruct the data when combined with the embedding. Even when curious server and user collude to disclose the secret parameters, they cannot accurately recover the data. Another byproduct of our approach is that it reduces the complexity of the search and the required storage space. We show the interest of our work in a benchmark biometrics dataset, where we verify our theoretical analysis with real data.

Providing a global understanding of privacy is crucial, because everything is connected. Nowadays companies are providing their customers with more services that will give them more access to their data and daily activity; electricity companies are marketing the new smart meters as a new service with great benefit to reduce the electricity usage by monitoring the electricity reading in real time. Although the users might benefit from this extra service, it will compromise the privacy of the users by having constant access to the readings. Since the smart meters will provide the users with real electricity readings, they will be able to decide and identify which devices are consuming energy in that specific moment and how much it will cost. This kind of information can be exploited by numerous types of people. Unauthorized use of this information is an invasion of privacy and may lead to much more severe consequences. This paper will propose an algorithm approach for the comparison and analysis of Smart Meter data readings, considering the time and temperature factors at each second to identify the use patterns at each house by identifying the appliances activities at each second in time complexity O(log(m)).

The paper focuses on one of the methods of designing a highly-automated hardware-software complex aimed at controlling the security of power grids and units that support both central heating and power systems of smart cities. We understand this condition as a situation when any energy consumers of smart cities will be provided with necessary for their living amounts of energy and fuel at any time, including possible periods of techno genic and natural hazards. Two main scientific principles lie in the base of the approach introduced. The first one is diversification of risks of energy security of smart cities by rational choosing the different energy generation sources ratio for fuel-energy balance of a smart city, including large fuel electric power plants and small power autonomous generators. For example, they can be wind energy machinery of sun collectors, heat pipes, etc. The second principle is energy efficiency and energy saving of smart cities. In our case this principle is realized by the high level of automation of monitoring and operation of security status of energy systems and complexes that provide the consumers of smart cities with heat, hot water and electricity, as well as by preventive alert of possible emergencies and high reliability of functioning of all energy facilities. We formulate the main principle governing the construction of a smart hardware-software complex used to maintain a highly-automated control over risks connected with functioning of both power sources and transmission grids. This principle is for open block architecture, including highly autonomous block-modules of primary registration of measuring information, data analysis and systems of automated operation. It also describes general IT-tools used to control the risks of supplying smart cities with energy and shows the structure of a highly-automated system designed to select technological and managerial solutions for a smart city's energy supply system.

With the emergence of the internet of things (IoT) and participatory sensing (PS) paradigms trustworthiness of remotely sensed data has become a vital research question. In this work, we present the design of a trusted sensor, which uses physically unclonable functions (PUFs) as anchor to ensure integrity, authenticity and non-repudiation guarantees on the sensed data. We propose trusted sensors for mobile devices to address the problem of potential manipulation of mobile sensors' readings by exploiting vulnerabilities of mobile device OS in participatory sensing for IoT applications. Preliminary results from our implementation of trusted visual sensor node show that the proposed security solution can be realized without consuming significant amount of resources of the sensor node.