Open Access

We propose eight usable security principles that provide software developers with a lightweight framework to help them integrate security in a user-friendly way. These principles should help developers who must weigh usability and security tradeoffs to facilitate adoption.

Login Data Set for Risk-Based Authentication Synthesized login feature data of >33M login attempts and >3.3M users on a large-scale online service in Norway. Original data collected between February 2020 and February 2021. This data sets aims to foster research and development for <a href="https://riskbasedauthentication.org">Risk-Based Authentication (RBA) systems. The data was synthesized from the real-world login behavior of more than 3.3M users at a large-scale single sign-on (SSO) online service in Norway.

Ziel der achten Auflage des wissenschaftlichen Workshops “Usable Security and Privacy” auf der Mensch und Computer 2022 ist es, aktuelle Forschungs- und Praxisbeiträge zu präsentieren und anschließend mit den Teilnehmenden zu diskutieren. Der Workshop soll ein etabliertes Forum fortführen und weiterentwickeln, in dem sich Experten aus verschiedenen Bereichen, z. B. Usability und Security Engineering, transdisziplinär austauschen können.

Continuous authentication has emerged as a promising approach to increase user account security for online services. Unlike traditional authentication methods, continuous authentication provides ongoing security throughout the session, protecting against session takeover attacks due to illegitimate access. The effectiveness of continuous authentication systems relies on the continuous processing of users' sensitive biometric data. To balance security and privacy trade-offs, it's crucial to understand when users are willing to disclose biometric data for enhanced account security, addressing inevitable privacy concerns and user acceptance. To address this knowledge gap, we conducted an online study with 830 participants from the U.S., aiming to investigate user perceptions towards continuous authentication across different classes of online services. Our analysis identified four groups of biometric traits that directly reflect users' willingness to disclose them. Our findings demonstrate that willingness to disclose is influenced by both the specific biometric traits and the type of online service involved. User perceptions are strongly shaped by factors such as response efficacy, perceived privacy risks associated with the biometric traits, and concerns about the service providers' handling of such data. Our results emphasize the inadequacy of one-size-fits-all solutions and provide valuable insights for the design and implementation of continuous authentication systems.

HTTP client hints are a set of standardized HTTP request headers designed to modernize and potentially replace the traditional user agent string. While the user agent string exposes a wide range of information about the client's browser and device, client hints provide a controlled and structured approach for clients to selectively disclose their capabilities and preferences to servers. Essentially, client hints aim at more effective and privacy-friendly disclosure of browser or client properties than the user agent string. We present a first long-term study of the use of HTTP client hints in the wild. We found that despite being implemented in almost all web browsers, server-side usage of client hints remains generally low. However, in the context of third-party websites, which are often linked to trackers, the adoption rate is significantly higher. This is concerning because client hints allow the retrieval of more data from the client than the user agent string provides, and there are currently no mechanisms for users to detect or control this potential data leakage. Our work provides valuable insights for web users, browser vendors, and researchers by exposing potential privacy violations via client hints and providing help in developing remediation strategies as well as further research.

Contemporary software is inherently distributed. The principles guiding the design of such software have been mainly manifested by the service-oriented architecture (SOA) concept. In a SOA, applications are orchestrated by software services generally operated by distinct entities. Due to the latter fact, service security has been of importance in such systems ever since. A dominant protocol for implementing SOA-based systems is SOAP, which comes with a well-elaborated security framework. As an alternative to SOAP, the architectural style representational state transfer (REST) is gaining traction as a simple, lightweight and flexible guideline for designing distributed service systems that scale at large. This paper starts by introducing the basic constraints representing REST. Based on these foundations, the focus is afterwards drawn on the security needs of REST-based service systems. The limitations of transport-oriented protection means are emphasized and the demand for specific message-oriented safeguards is assessed. The paper then reviews the current activities in respect to REST-security and finds that the available schemes are mostly HTTP-centered and very heterogeneous. More importantly, all of the analyzed schemes contain vulnerabilities. The paper contributes a methodology on how to establish REST-security as a general security framework for protecting REST-based service systems of any kind by consistent and comprehensive protection means. First adoptions of the introduced approach are presented in relation to REST message authentication with instantiations for REST-ful HTTP (web/cloud services) and REST-ful constraint application protocol (CoAP) (internet of things (IoT) services).

Das Auslesen von Messdaten in elektronischer Form ermöglicht es, diese vom Ursprung bis zur Rechnungsstellung effizient und ohne Medienbruch zu erheben und zu verarbeiten. Gerade im liberalisierten Energiemarkt ist dies von Bedeutung, da eine Vielzahl von Marktteilnehmern miteinander kommunizieren muss. Das im VERNET-Programm geförderte SELMA-Projekt verfolgt das Ziel, einen Standard für den sicheren elektronischen Austausch von Messdaten zu entwickeln und zu etablieren. Eine der zentralen Anforderungen ist die Gewährleistung der Authentizität und Integrität der über offene Netze ausgelesenen Messdaten, die über die gesamte Lebensdauer der Messdaten nachprüfbar sein sollen. Die technische Umsetzung dieser Anforderungen resultiert in einer Sicherheitsarchitektur, die durch den durchgängigen Einsatz elektronischer Signaturen gekennzeichnet ist. Mit den signierten Datensätzen können die Rechnungen von den Marktteilnehmern auf ihre Authentizität und Integrität hin überprüft werden. Dieser Beitrag zeigt die gesetzgeberischen Hindernisse auf, die bei der Umsetzung der Anforderungen an qualifizierte Signaturen im elektronischen Messdatenaustausch auftreten und wie dennoch eine größtmögliche Beweiskraft für fortgeschrittene Signaturen erreicht werden kann.

Data transfer and staging services are common components in Grid-based, or more generally, in service-oriented applications. Security mechanisms play a central role in such services, especially when they are deployed in sensitive application fields like e-health. The adoption of WS-Security and related standards to SOAP-based transfer services is, however, problematic as a straightforward adoption of SOAP with MTOM introduces considerable inefficiencies in the signature generation process when large data sets are involved. This paper proposes a non-blocking, signature generation approach enabling a stream-like processing with considerable performance enhancements.

We present a systematization of usable security principles, guidelines and patterns to facilitate the transfer of existing knowledge to researchers and practitioners. Based on a literature review, we extracted 23 principles, 11 guidelines and 47 patterns for usable security and identified their interconnection. The results indicate that current research tends to focus on only a subset of important principles. The fact that some principles are not yet addressed by any design patterns suggests that further work on refining these patterns is needed. We developed an online repository, which stores the harmonized principles, guidelines and patterns. The tool enables users to search for relevant guidance and explore it in an interactive and programmatic manner. We argue that both the insights presented in this article and the web-based repository will be highly valuable for students to get a good overview, practitioners to implement usable security and researchers to identify areas of future research.

When entering a password (or other secrets) the typed input is most commonly masked, i.e. the characters are hidden behind bullets or asterisks. This, however, complicates the input and highly decreases the user's confident causing several issues such as login failure attempts. On the other hand, password masking is an important security requirement for a lot of applications and contexts to prevent a third person to read the password. Thus, simply dropping password masking is not feasible in general. A common solution provides the user with the choice of toggling password masking on and off, but due to distinct defaults (in dependency of the application and context) this is rather complex and confusing. Enhanced password visualization technologies beyond the simple masking of passwords can provide more sophisticated solutions from both a usability and security perspective. In this paper, available password visualization technologies are presented and discussed. Furthermore a novel password visualization approach is introduced, the TransparentMask, which provides unique properties in comparison to the existing schemes. Amongst these are the ability to detect mistakes while typing and being able to localize and correct the typo within a certain range. Finally, a security analysis of the TransparentMask shows that the protection level given by a certain password length is slightly decreased in comparison to the fully masked approach.

XML Encryption and XML Signature are fundamental security standards forming the core for many applications which require to process XML-based data. Due to the increased usage of XML in distributed systems and platforms such as in SOA and Cloud settings, the demand for robust and effective security mechanisms increased as well. Recent research work discovered, however, substantial vulnerabilities in these standards as well as in the vast majority of the available implementations. Amongst them, the so-called XML Signature Wrapping attack belongs to the most relevant ones. With the many possible instances of this attack type, it is feasible to annul security systems relying on XML Signature and to gain access to protected resources as has been successfully demonstrated lately for various Cloud infrastructures and services. This paper contributes a comprehensive approach to robust and effective XML Signatures for SOAP-based Web Services. An architecture is proposed, which integrates the r equired enhancements to ensure a fail-safe and robust signature generation and verification. Following this architecture, a hardened XML Signature library has been implemented. The obtained evaluation results show that the developed concept and library provide the targeted robustness against all kinds of known XML Signature Wrapping attacks. Furthermore the empirical results underline, that these security merits are obtained at low efficiency and performance costs as well as remain compliant with the underlying standards.