Usability and Trust in Information Systems

The need for people to protect themselves and their assets is as old as humankind. People's physical safety and their possessions have always been at risk from deliberate attack or accidental damage. The advance of information technology means that many individuals, as well as corporations, have an additional range of physical (equipment) and electronic (data) assets that are at risk. Furthermore, the increased number and types of interactions in cyberspace has enabled new forms of attack on people and their possessions. Consider grooming of minors in chat-rooms, or Nigerian email cons: minors were targeted by paedophiles before the creation of chat-rooms, and Nigerian criminals sent the same letters by physical mail or fax before there was email. But the technology has decreased the cost of many types of attacks, or the degree of risk for the attackers. At the same time, cyberspace is still new to many people, which means they do not understand risks, or recognise the signs of an attack, as readily as they might in the physical world. The IT industry has developed a plethora of security mechanisms, which could be used to mitigate risks or make attacks significantly more difficult. Currently, many people are either not aware of these mechanisms, or are unable or unwilling or to use them. Security experts have taken to portraying people as "the weakest link" in their efforts to deploy effective security [e.g. Schneier, 2000]. However, recent research has revealed at least some of the problem may be that security mechanisms are hard to use, or be ineffective. The review summarises current research on the usability of security mechanisms, and discusses options for increasing their usability and effectiveness

A comprehensive study of the usability of multiple graphical passwords

Recognition-based graphical authentication systems (RBGSs) using images as passwords have been proposed as one potential solution to the need for more usable authentication. The rapid increase in the technologies requiring user authentication has increased the number of passwords that users have to remember. But nearly all prior work with RBGSs has studied the usability of a single password. In this paper, we present the first published comparison of the usability of multiple graphical passwords with four different image types: Mikon, doodle, art and everyday objects (food, buildings, sports etc.). A longi-tudinal experiment was performed with 100 participants over a period of 8 weeks, to examine the usability performance of each of the image types. The re-sults of the study demonstrate that object images are most usable in the sense of being more memorable and less time-consuming to employ, Mikon images are close behind but doodle and art images are significantly inferior. The results of our study complement cognitive literature on the picture superiority effect, vis-ual search process and nameability of visually complex images

Changing users' security behaviour towards security questions: A game based learning approach

Fallback authentication is used to retrieve forgotten passwords. Security questions are one of the main techniques used to conduct fallback authentication. In this paper, we propose a serious game design that uses system-generated security questions with the aim of improving the usability of fallback authentication. For this purpose, we adopted the popular picture-based "4 Pics 1 word" mobile game. This game was selected because of its use of pictures and cues, which previous psychology research found to be crucial to aid memorability. This game asks users to pick the word that relates to the given pictures. We then customized this game by adding features which help maximize the following memory retrieval skills: (a) verbal cues - by providing hints with verbal descriptions, (b) spatial cues - by maintaining the same order of pictures, (c) graphical cues - by showing 4 images for each challenge, (d) interactivity/engaging nature of the game.Comment: 6, Military Communications and Information Systems Conference (MilCIS), 2017. arXiv admin note: substantial text overlap with arXiv:1707.0807

Lessons learned from evaluating eight password nudges in the wild

Background. The tension between security and convenience, when creating passwords, is well established. It is a tension that often leads users to create poor passwords. For security designers, three mitigation strategies exist: issuing passwords, mandating minimum strength levels or encouraging better passwords. The first strategy prompts recording, the second reuse, but the third merits further investigation. It seemed promising to explore whether users could be subtly nudged towards stronger passwords.Aim. The aim of the study was to investigate the influence of visual nudges on self-chosen password length and/or strength.Method. A university application, enabling students to check course dates and review grades, was used to support two consecutive empirical studies over the course of two academic years. In total, 497 and 776 participants, respectively, were randomly assigned either to a control or an experimental group. Whereas the control group received no intervention, the experimental groups were presented with different visual nudges on the registration page of the web application whenever passwords were created. The experimental groups’ password strengths and lengths were then compared that of the control group.Results. No impact of the visual nudges could be detected, neither in terms of password strength nor length. The ordinal score metric used to calculate password strength led to a decrease in variance and test power, so that the inability to detect an effect size does not definitively indicate that such an effect does not exist.Conclusion. We cannot conclude that the nudges had no effect on password strength. It might well be that an actual effect was not detected due to the experimental design choices. Another possible explanation for our result is that password choice is influenced by the user’s task, cognitive budget, goals and pre-existing routines. A simple visual nudge might not have the power to overcome these forces. Our lessons learned therefore recommend the use of a richer password strength quantification measure, and the acknowledgement of the user’s context, in future studies

Understanding Shoulder Surfing in the Wild: Stories from Users and Observers

Research has brought forth a variety of authentication systems to mitigate observation attacks. However, there is little work about shoulder surfing situations in the real world. We present the results of a user survey (N=174) in which we investigate actual stories about shoulder surfing on mobile devices from both users and observers. Our analysis indicates that shoulder surfing mainly occurs in an opportunistic, non-malicious way. It usually does not have serious consequences, but evokes negative feelings for both parties, resulting in a variety of coping strategies. Observed data was personal in most cases and ranged from information about interests and hobbies to login data and intimate details about third persons and relationships. Thus, our work contributes evidence for shoulder surfing in the real world and informs implications for the design of privacy protection mechanisms

On Ladder Logic Bombs in Industrial Control Systems

In industrial control systems, devices such as Programmable Logic Controllers (PLCs) are commonly used to directly interact with sensors and actuators, and perform local automatic control. PLCs run software on two different layers: a) firmware (i.e. the OS) and b) control logic (processing sensor readings to determine control actions). In this work, we discuss ladder logic bombs, i.e. malware written in ladder logic (or one of the other IEC 61131-3-compatible languages). Such malware would be inserted by an attacker into existing control logic on a PLC, and either persistently change the behavior, or wait for specific trigger signals to activate malicious behaviour. For example, the LLB could replace legitimate sensor readings with manipulated values. We see the concept of LLBs as a generalization of attacks such as the Stuxnet attack. We introduce LLBs on an abstract level, and then demonstrate several designs based on real PLC devices in our lab. In particular, we also focus on stealthy LLBs, i.e. LLBs that are hard to detect by human operators manually validating the program running in PLCs. In addition to introducing vulnerabilities on the logic layer, we also discuss countermeasures and we propose two detection techniques.Comment: 11 pages, 14 figures, 2 tables, 1 algorith