On Deception-Based Protection Against Cryptographic Ransomware

in Proceedings of the 16th Conference on Detection of Intrusions and Malware & Vulnerability Assessment (2019)

In order to detect malicious file system activity, some commercial and academic anti-ransomware solutions implement deception-based techniques, specifically by placing decoy files among user files. While ... [more ▼]

In order to detect malicious file system activity, some commercial and academic anti-ransomware solutions implement deception-based techniques, specifically by placing decoy files among user files. While this approach raises the bar against current ransomware, as any access to a decoy file is a sign of malicious activity, the robustness of decoy strategies has not been formally analyzed and fully tested. In this paper, we analyze existing decoy strategies and discuss how they are effective in countering current ransomware by defining a set of metrics to measure their robustness. To demonstrate how ransomware can identify existing deception-based detection strategies, we have implemented a proof-of-concept anti-decoy ransomware that successfully bypasses decoys by using a decision engine with few rules. Finally, we discuss existing issues in decoy-based strategies and propose practical solutions to mitigate them. [less ▲]

An Agile Approach to Validate a Formal Representation of the GDPR

in JSAI International Symposium on Artificial Intelligence (2019), 11717

Modeling in a knowledge base of logic formulæ the articles of the GDPR enables semi-automatic reasoning of the Regulation. To be legally substantiated, it requires that the formulæ express validly the ... [more ▼]

Modeling in a knowledge base of logic formulæ the articles of the GDPR enables semi-automatic reasoning of the Regulation. To be legally substantiated, it requires that the formulæ express validly the legal meaning of the Regulation’s articles. But legal experts are usually not familiar with logic, and this calls for an interdisciplinary validation methodology that bridges the communication gap between formal modelers and legal evaluators. We devise such a validation methodology and exemplify it over a knowledge base of articles of the GDPR translated <br />AQ2 into Reified I/O (RIO) logic and encoded in LegalRuleML. A pivotal element of the methodology is a human-readable intermediate representation of the logic formulæ that preserves the formulæ’s meaning while rendering it in a readable way to non-experts. After being applied over a use case, we prove that it is possible to retrieve feedback from legal experts about the formal representation of Art. 5.1a and Art. 7.1. What emerges is an agile process to build logic knowledge bases of legal texts, and to support their public trust, which we intend to use for a logic AQ3 model of the GDPR, called DAPRECO knowledge base. [less ▲]

A Formal Security Analysis of the pEp Authentication Protocol for Decentralized Key Distribution and End-to-End Encrypted Email

in Emerging Technologies for Authorization and Authentication (2019)

To send encrypted emails, users typically need to create and exchange keys which later should be manually authenticated, for instance, by comparing long strings of characters. These tasks are cumbersome ... [more ▼]

To send encrypted emails, users typically need to create and exchange keys which later should be manually authenticated, for instance, by comparing long strings of characters. These tasks are cumbersome for the average user. To make more accessible the use of encrypted email, a secure email application named pEp automates the key management operations; pEp still requires the users to carry out the verification, however, the authentication process is simple: users have to compare familiar words instead of strings of random characters, then the application shows the users what level of trust they have achieved via colored visual indicators. Yet, users may not execute the authentication ceremony as intended, pEp's trust rating may be wrongly assigned, or both. To learn whether pEp's trust ratings (and the corresponding visual indicators) are assigned consistently, we present a formal security analysis of pEp's authentication ceremony. From the software implementation in C, we derive the specifications of an abstract protocol for public key distribution, encryption and trust establishment; then, we model the protocol in a variant of the applied pi calculus and later formally verify and validate specific privacy and authentication properties. We also discuss alternative research directions that could enrich the analysis. [less ▲]

A Protocol to Strengthen Password-Based Authentication

in Emerging Technologies for Authorization and Authentication (2018, November)

We discuss a password-based authentication protocol that we argue to be robust against password-guessing and o -line dictionary attacks. The core idea is to hash the passwords with a seed that comes from ... [more ▼]

We discuss a password-based authentication protocol that we argue to be robust against password-guessing and o -line dictionary attacks. The core idea is to hash the passwords with a seed that comes from an OTP device, making the resulting identity token unpredictable for an adversary. We believe that the usability of this new protocol is the same as that of password-based methods with OTP, but has the advan- tage of not burdening users with having to choose strong passwords. [less ▲]

Cholesteric Liquid Crystal Shells as Enabling Material for Information-Rich Design and Architecture.

in Advanced Materials (2018)

The responsive and dynamic character of liquid crystals (LCs), arising from their ability to self-organize into long-range ordered structures while maintaining fluidity, has given them a role as key ... [more ▼]

The responsive and dynamic character of liquid crystals (LCs), arising from their ability to self-organize into long-range ordered structures while maintaining fluidity, has given them a role as key enabling materials in the information technology that surrounds us today. Ongoing research hints at future LC-based technologies of entirely different types, for instance by taking advantage of the peculiar behavior of cholesteric liquid crystals (CLCs) subject to curvature. Spherical shells of CLC reflect light omnidirectionally with specific polarization and wavelength, tunable from the UV to the infrared (IR) range, with complex patterns arising when many of them are brought together. Here, these properties are analyzed and explained, and future application opportunities from an inter- disciplinary standpoint are discussed. By incorporating arrangements of CLC shells in smart facades or vehicle coatings, or in objects of high value subject to counterfeiting, game-changing future uses might arise in fields spanning infor- mation security, design, and architecture. The focus here is on the challenges of a digitized and information-rich future society where humans increasingly rely on technology and share their space with autonomous vehicles, drones, and robots. [less ▲]

No Random, No Ransom: A Key to Stop Cryptographic Ransomware

in Proceedings of the 15th Conference on Detection of Intrusions and Malware, and Vulnerability Assessment (2018)

To be effective, ransomware has to implement strong encryption, and strong encryption in turn requires a good source of random numbers. Without access to true randomness, ransomware relies on the pseudo ... [more ▼]

To be effective, ransomware has to implement strong encryption, and strong encryption in turn requires a good source of random numbers. Without access to true randomness, ransomware relies on the pseudo random number generators that modern Operating Systems make available to applications. With this insight, we propose a strategy to mitigate ransomware attacks that considers pseudo random number generator functions as critical resources, controls accesses on their APIs and stops unauthorized applications that call them. Our strategy, tested against 524 active real-world ransomware samples, stops 94% of them, including WannaCry, Locky, CryptoLocker and CryptoWall. Remarkably, it also nullifies NotPetya, the latest offspring of the family which so far has eluded all defenses. [less ▲]

A Security Analysis, and a Fix, of a Code-Corrupted Honeywords System

in Proceedings of the 4th International Conference on Information Systems Security and Privacy (2018)

In 2013 Juels and Rivest introduced the Honeywords System, a password-based authentication system designed to detect when a password file has been stolen. A Honeywords System stores passwords together ... [more ▼]

In 2013 Juels and Rivest introduced the Honeywords System, a password-based authentication system designed to detect when a password file has been stolen. A Honeywords System stores passwords together with indistinguishable decoy words so when an intruder steals the file, retrieves the words, and tries to log-in, he does not know which one is the password. By guessing one from the decoy words, he may not be lucky and reveal the leak. Juels and Rivest left a problem open: how to make the system secure even when the intruder corrupted the login server’s code. In this paper we study and solve the problem. However, since “code corruption” is a powerful attack, we first define rigorously the threat and set a few assumptions under which the problem is still solvable, before showing meaningful attacks against the original Honeywords System. Then we elicit a fundamental security requirement, implementing which, we are able to restore the honeywords System’s security despite a corrupted login service. We verify the new protocol’s security formally, using ProVerif for this task. We also implement the protocol and test its performance. Finally, at the light of our findings, we discuss whether it is still worth using a fixed honeywords-based system against such a powerful threat, or whether it is better, in order to be resilient against code corruption attacks, to design afresh a completely different password-based authentication solution. [less ▲]

Security in the Shell : An Optical Physical Unclonable Function made of Shells of Cholesteric Liquid Crystals

in Proc. of the 9th IEEE Workshop on Information Forensics and Security (2017, October 02)

We describe the application in security of shells of Cholesteric Liquid Crystals (ChLCs). Such shells have a diameter in the microns range and can be gathered in hundreds in a surface area as small as a ... [more ▼]

We describe the application in security of shells of Cholesteric Liquid Crystals (ChLCs). Such shells have a diameter in the microns range and can be gathered in hundreds in a surface area as small as a nail’s head. Because of their structural properties, a bundle of them reflects light, creating colorful patterns that we argue to be unique and computationally hard to predict. We argue also that the bundle itself is unclonable. These are typical properties of Physically Unclonable Functions, a family to which shells of ChLCs belong too. Herein we discuss their physical and security properties and their potential use in object authentication. [less ▲]

Trustworthy exams without trusted parties

in Computer and Security (2017), 67

Historically, exam security has mainly focused on threats ascribed to candidate cheating. Such threats have been normally mitigated by invigilation and anti-plagiarism methods. However, as recent exam ... [more ▼]

Historically, exam security has mainly focused on threats ascribed to candidate cheating. Such threats have been normally mitigated by invigilation and anti-plagiarism methods. However, as recent exam scandals confirm, also invigilators and authorities may pose security threats. The introduction of computers into the different phases of an exam, such as candidate registration, brings new security issues that should be addressed with the care normally devoted to security protocols. This paper proposes a protocol that meets a wide set of security requirements and resists threats that may originate from candidates as well as from exam administrators. By relying on a combination of oblivious transfer and visual cryptography schemes, the protocol does not need to rely on any trusted third party. We analyse the protocol formally in ProVerif and prove that it verifies all the stated security requirements. [less ▲]

Human Rights in the era of Information and Communication Technology

Speeches/Talks (2017)