Android is the most widely deployed end-user focused operating system. With its growing set of use cases encompassing communication, navigation, media consumption, entertainment, finance, health, and access to sensors, actuators, cameras, or microphones, its underlying security model needs to address a host of practical threats in a wide variety of scenarios while being useful to non-security experts

We present a secure two-factor authentication (TFA) scheme based on the user’s possession of a password and a crypto-capable device. Security is “end-to-end” in the sense that the attacker can attack all parts of the system, including all communication links and any subset of parties (servers, devices, client terminals), can learn users’ passwords, and perform active and passive attacks, online and

Searchable Encryption (SE) is a technique that allows Cloud Service Providers to search over encrypted datasets without learning the content of queries and records. In recent years, many SE schemes have been proposed to protect outsourced data. However, most of them leak sensitive information, from which attackers could still infer the content of queries and records by mounting leakage-based inference

In this article, we present a thorough evaluation of semantic password grammars. We report multifactorial experiments that test the impact of sample size, probability smoothing, and linguistic information on password cracking. The semantic grammars are compared with state-of-the-art probabilistic context-free grammar (PCFG) and neural network models, and tested in cross-validation and A vs. B scenarios

IoT platforms enable users to connect various smart devices and online services via reactive apps running on the cloud. These apps, often developed by third-parties, perform simple computations on data triggered by external information sources and actuate the results of computations on external information sinks. Recent research shows that unintended or malicious interactions between the different

As network security monitoring grows more sophisticated, there is an increasing need for outsourcing such tasks to third-party analysts. However, organizations are usually reluctant to share their network traces due to privacy concerns over sensitive information, e.g., network and system configuration, which may potentially be exploited for attacks. In cases where data owners are convinced to share

Mobile application security has been a major area of focus for security research over the course of the last decade. Numerous application analysis tools have been proposed in response to malicious, curious, or vulnerable apps. However, existing tools, and specifically, static analysis tools, trade soundness of the analysis for precision and performance and are hence soundy. Unfortunately, the specific

Spurious power consumption data reported from compromised meters controlled by organized adversaries in the Advanced Metering Infrastructure (AMI) may have drastic consequences on a smart grid’s operations. While existing research on data falsification in smart grids mostly defends against isolated electricity theft, we introduce a taxonomy of various data falsification attack types, when smart meters

Dynamic languages, such as JavaScript, employ string-to-code primitives to turn dynamically generated text into executable code at run-time. These features make standard static analysis extremely hard if not impossible, because its essential data structures, i.e., the control-flow graph and the system of recursive equations associated with the program to analyze, are themselves dynamically mutating

Malware analysis is an essential task to understand infection campaigns, the behavior of malicious codes, and possible ways to mitigate threats. Malware analysis also allows better assessment of attackers’ capabilities, techniques, and processes. Although a substantial amount of previous work provided a comprehensive analysis of the international malware ecosystem, research on regionalized, country-

The ability to measure privacy accurately and consistently is key in the development of new privacy protections. However, recent studies have uncovered weaknesses in existing privacy metrics, as well as weaknesses caused by the use of only a single privacy metric. Metrics suites, or combinations of privacy metrics, are a promising mechanism to alleviate these weaknesses, if we can solve two open problems:

Passwords are still the most widespread means for authenticating users, even though they have been shown to create huge security problems. This motivated the use of additional authentication mechanisms in so-called multi-factor authentication protocols. In this article, we define a detailed threat model for this kind of protocol: While in classical protocol analysis attackers control the communication

Unsafe programming systems are still very popular, despite the shortcomings due to several published memory-corruption vulnerabilities. Toward defending memory corruption, compilers have started to employ advanced software hardening such as Control-flow Integrity (CFI) and SafeStack. However, there is a broad interest for realizing compilers that impose memory safety with no heavy runtime support (e

Most research in the field of network intrusion detection heavily relies on datasets. Datasets in this field, however, are scarce and difficult to reproduce. To compare, evaluate, and test related work, researchers usually need the same datasets or at least datasets with similar characteristics as the ones used in related work. In this work, we present concepts and the Intrusion Detection Dataset Toolkit

Cyber security decision making is inherently complicated, with nearly every decision having knock-on consequences for an organisation’s vulnerability and exposure. This is further compounded by the fact that decision-making actors are rarely security experts and may have an incomplete understanding of the security that the organisation currently has in place. They must contend with a multitude of possible

Growing multi-stage attacks in computer networks impose significant security risks and necessitate the development of effective defense schemes that are able to autonomously respond to intrusions during vulnerability windows. However, the defender faces several real-world challenges, e.g., unknown likelihoods and unknown impacts of successful exploits. In this article, we leverage reinforcement learning

Observation Resilient Authentication Schemes (ORAS) are a class of shared secret challenge–response identification schemes where a user mentally computes the response via a cognitive function to authenticate herself such that eavesdroppers cannot readily extract the secret. Security evaluation of ORAS generally involves quantifying information leaked via observed challenge–response pairs. However,

Fingerprinting of various physical and logical devices has been proposed for uniquely identifying users or devices of mainstream IT systems such as PCs, laptops, and smart phones. However, the application of such techniques in Industrial Control Systems (ICS) is less explored for reasons such as a lack of direct access to such systems and the cost of faithfully reproducing realistic threat scenarios

In this article, we investigate a fundamental question regarding software security: Is the security of SW releases increasing over time? We approach this question with a detailed analysis of the large body of open-source software packaged in the popular Debian GNU/Linux distribution. Contrary to common intuition, we find no clear evidence that the vulnerability rate of widely used software decreases

App stores provide access to millions of different programs that users can download on their computers. Developers can also make their programs available for download on their websites and host the program files either directly on their website or on third-party platforms, such as mirrors. In the latter case, as users download the software without any vetting from the developers, they should take the

Malicious domains, including phishing websites, spam servers, and command and control servers, are the reason for many of the cyber attacks nowadays. Thus, detecting them in a timely manner is important to not only identify cyber attacks but also take preventive measures. There has been a plethora of techniques proposed to detect malicious domains by analyzing Domain Name System (DNS) traffic data

Neo4j is a popular graph database that offers two versions: an enterprise edition and a community edition. The enterprise edition offers customizable Role-based Access Control features through custom developed procedures, while the community edition does not offer any access control support. Being a graph database, Neo4j appears to be a natural application for Relationship-Based Access Control (ReBAC)

Modern smartphone sensors can be leveraged for providing novel functionality and greatly improving the user experience. However, sensor data can be misused by privacy-invasive or malicious entities. Additionally, a wide range of other attacks that use mobile sensor data have been demonstrated; while those attacks have typically relied on users installing malicious apps, browsers have eliminated that

Software protection aims at safeguarding assets embedded in software by preventing and delaying reverse engineering and tampering attacks. This article presents an architecture and supporting tool flow to renew parts of native applications dynamically. Renewed and diversified code and data belonging to either the original application or to linked-in protections are delivered from a secure server to

Cybersecurity experts have appraised the total global cost of malicious hacking activities to be $450 billion annually. Cyber Threat Intelligence (CTI) has emerged as a viable approach to combat this societal issue. However, existing processes are criticized as inherently reactive to known threats. To combat these concerns, CTI experts have suggested proactively examining emerging threats in the vast

The latest smartphones have started providing multiple authentication options including PINs, patterns, and passwords (knowledge based), as well as face, fingerprint, iris, and voice identification (biometric-based). In this article, we conducted two user studies to investigate how the convenience and security of unlocking phones are influenced by the provision of multiple authentication options. In

Bluetooth (BR/EDR) and Bluetooth Low Energy (BLE) are pervasive wireless technologies specified in the Bluetooth standard. The standard includes key negotiation protocols used to generate long-term keys (during pairing) and session keys (during secure connection establishment). In this work, we demonstrate that the key negotiation protocols of Bluetooth and BLE are vulnerable to standard-compliant

Fire alarm and signaling systems are a networked system of fire detectors, fire control units, automated fire extinguishers, and fire notification appliances. Malfunction of these safety-critical cyber-physical systems may lead to chaotic evacuations, property damage, and even loss of human life. Therefore, reliability is one of the most crucial factors for fire detectors. Indeed, even a single report

Random numbers are essential for cryptography and scientific simulation. Generating truly random numbers for cryptography can be a slow and expensive process. Quantum physics offers a variety of promising solutions to this challenge, proposing sources of entropy that may be genuinely unpredictable, based on the inherent randomness of certain physical phenomena. These properties have been employed to

Online Social Networks (OSNs) offer free storage and social networking services through which users can communicate personal information with one another. The personal information of the users collected by the OSN provider comes with privacy problems when being monetized for advertising purposes. To protect user privacy, existing studies propose utilizing data encryption that immediately prevents OSNs

Over the last few years, there has been an almost exponential increase in the number of mobile applications that deal with sensitive data, such as applications for e-commerce or health. When dealing with sensitive data, classical authentication solutions based on username-password pairs are not enough, and multi-factor authentication solutions that combine two or more authentication factors of different

Faced with the threats posed by man-in-the-middle attacks, messaging platforms rely on “out-of-band” authentication, assuming that users have access to an external channel for authenticating one short value. For example, assuming that users recognizing each other’s voice can authenticate a short value, Telegram and WhatApp ask their users to compare 288-bit and 200-bit values, respectively. The existing

Typical security contests focus on breaking or mitigating the impact of buggy systems. We present the Build-it, Break-it, Fix-it (BIBIFI) contest, which aims to assess the ability to securely build software, not just break it. In BIBIFI, teams build specified software with the goal of maximizing correctness, performance, and security. The latter is tested when teams attempt to break other teams’ submissions

Text-based CAPTCHAs remains a popular scheme for distinguishing between a legitimate human user and an automated program. This article presents a novel genetic text captcha solver based on the generative adversarial network. As a departure from prior text captcha solvers that require a labor-intensive and time-consuming process to construct, our scheme needs significantly fewer real captchas but yields

The web is a tangled mass of interconnected services, whereby websites import a range of external resources from various third-party domains. The latter can also load further resources hosted on other domains. For each website, this creates a dependency chain underpinned by a form of implicit trust between the first-party and transitively connected third parties. The chain can only be loosely controlled

We propose a new clock synchronization architecture for systems under time transfer attacks. Facilitated by a feedforward control with feedback trim--based clock adjustment, coupled with packet filtering and frequency shaping techniques, our proposed architecture bounds the clock errors in the presence of a powerful network attacker capable of attacking packets between a master and a client. A key

Privacy notices and consent forms are the means of conveying privacy policy information to users. In Europe, a valid consent needs to be confirmed by a clear affirmative action. Despite previous research, it is not yet clear whether user engagement with consent forms via different types of interactions for confirming consent may play a significant role in effectively drawing user attention to the content

Research in Keystroke-Dynamics (KD) has customarily focused on temporal features without considering context to generate user templates that are used in authentication. Additionally, work on KD in hand-held devices such as smart-phones and tablets have shown that these features alone do not perform satisfactorily for authentication. In this work, we analyze the discriminatory power of the most-used

We apply formal methods to lay and streamline theoretical foundations to reason about Cyber-Physical Systems (CPSs) and physics-based attacks, i.e., attacks targeting physical devices. We focus on a formal treatment of both integrity and denial of service attacks to sensors and actuators of CPSs, and on the timing aspects of these attacks. Our contributions are fourfold. (1) We define a hybrid process

Keystroke behaviour-based authentication employs the unique typing behaviour of users to authenticate them. Recent such proposals for virtual keyboards on smartphones employ diverse temporal, contact, and spatial features to achieve over 95% accuracy. Consequently, they have been suggested as a second line of defense with text-based password authentication. We show that a state-of-the-art keystroke

Oblivious Random Access Machine (ORAM) allows a client to hide the access pattern when accessing sensitive data on a remote server. It is known that there exists a logarithmic communication lower bound on any passive ORAM construction, where the server only acts as the storage service. This overhead, however, was shown costly for some applications. Several active ORAM schemes with server computation

Location-based services (LBSs) typically crowdsource geo-tagged data from mobile users. Collecting more data will generally improve the utility for LBS providers; however, it also leads to more privacy exposure of users’ mobility patterns. Although the tension between data utility and user privacy has been recognized, there lacks a solution that determines how much data to collect—in both spatial and

Location-Based Services (LBSs) provide valuable services, with convenient features for mobile users. However, the location and other information disclosed through each query to the LBS erodes user privacy. This is a concern especially because LBS providers can be honest-but-curious, collecting queries and tracking users’ whereabouts and infer sensitive user data. This motivated both centralized and

With the increasing concerns over privacy in software systems, there is a growing enthusiasm to develop methods to support the development of privacy aware software systems. Inadequate privacy in software system designs could result in users losing their sensitive data, such as health information and financial information, which may cause financial and reputation loss. Privacy Engineering Methodologies

A method for detecting electronic data theft from computer networks is described, capable of recognizing patterns of remote exfiltration occurring over days to weeks. Normal traffic flow data, in the form of a host’s ingress and egress bytes over time, is used to train an ensemble of one-class learners. The detection ensemble is modular, with individual classifiers trained on different traffic features

Voice-over-IP (VoIP) software are among the most widely spread and pervasive software, counting millions of monthly users. However, we argue that people ignore the drawbacks of transmitting information along with their voice, such as keystroke sounds—as such sound can reveal what someone is typing on a keyboard. In this article, we present and assess a new keyboard acoustic eavesdropping attack that

Dynamic group key agreement protocols are cryptographic primitives to provide secure group communications in decentralized and dynamic networks. Such protocols provide additional operations to update the group key while adding new participants into the group and removing existing participants from the group without re-executing the protocol from the beginning. However, the lack of scalability emerges

The quantity of personal data that is collected, stored, and subsequently processed continues to grow rapidly. Given its sensitivity, ensuring privacy protections has become a necessary component of database management. To enhance protection, a number of mechanisms have been developed, such as audit logging and alert triggers, which notify administrators about suspicious activities. However, this approach

Images perturbed subtly to be misclassified by neural networks, called adversarial examples, have emerged as a technically deep challenge and an important concern for several application domains. Most research on adversarial examples takes as its only constraint that the perturbed images are similar to the originals. However, real-world application of these ideas often requires the examples to satisfy

Trust in a microelectronics-based system can be characterized as the level of confidence that a system is free of subversive alterations made during system development, or that the development process of a system has not been manipulated by a malicious adversary. Trust in systems has become an increasing concern over the past decade. This article presents a novel game-theoretic framework, called GPLADD

We present a novel scheme called Decentralized Attestation for Device Swarms (DADS), which is, to the best of our knowledge, the first to accomplish decentralized attestation in device swarms. Device swarms are smart, mobile, and interconnected devices that operate in large numbers and are likely to be part of emerging applications in Cyber-Physical Systems (CPS) and Industrial Internet of Things (IIoTs)

Private record linkage protocols allow multiple parties to exchange matching records, which refer to the same entities or have similar values, while keeping the non-matching ones secret. Conventional protocols are based on computationally expensive cryptographic primitives and therefore do not scale. To address these scalability issues, hybrid protocols have been proposed that combine differential

The consumer drone market is booming. Consumer drones are predominantly used for aerial photography; however, their use has been expanding because of their autopilot technology. Unfortunately, terrorists have also begun to use consumer drones for kamikaze bombing and reconnaissance. To protect against such threats, several companies have started “anti-drone” services that primarily focus on disrupting

Kickstarted by the Digital Forensic Research Workshop (DFRWS) conference in 2005, modern memory analysis is now one of most active areas of computer forensics and it mostly focuses on techniques to locate key operating system data structures and extract high-level information. These techniques work on the assumption that the information inside a memory dump is consistent and the copy of the physical

Security monitoring has long been considered as a fundamental mechanism to mitigate the damage of a security attack. Recently, intra-level security systems have been proposed that can efficiently and securely monitor system software without any involvement of more privileged entity. Unfortunately, there exists no full intra-level security system that can universally operate at any privilege level on

While the logical centralization of functional properties of the network in Software-Defined Networking (SDN) brought advantages such as a faster pace of innovation, it also disrupted some of the natural defenses of traditional architectures against different threats. The literature on SDN has mostly been concerned with the functional side, despite some specific works concerning non-functional properties

Secure email is increasingly being touted as usable by novice users, with a push for adoption based on recent concerns about government surveillance. To determine whether secure email is ready for grassroots adoption, we employ a laboratory user study that recruits pairs of novice users to install and use several of the latest systems to exchange secure messages. We present both quantitative and qualitative

Passwords are widely used for user authentication, but they are often difficult for a user to recall, easily cracked by automated programs, and heavily reused. Security questions are also used for secondary authentication. They are more memorable than passwords, because the question serves as a hint to the user, but they are very easily guessed. We propose a new authentication mechanism, called “life-experience

The rise in popularity of the Android platform has resulted in an explosion of malware threats targeting it. As both Android malware and the operating system itself constantly evolve, it is very challenging to design robust malware mitigation techniques that can operate for long periods of time without the need for modifications or costly re-training. In this paper, we present MaMaDroid, an Android

The formal specification of privacy goals in symbolic protocol models has proved to be not quite trivial so far. The most widely used approach in formal methods is based on the static equivalence of frames in the applied pi-calculus, basically asking whether or not the intruder is able to distinguish two given worlds. But then a subtle question emerges: How can we be sure that we have specified all