A Framework for Reasoning About the Human in the Loop

Many secure systems rely on a “human in the loop” to perform security-critical functions. However, humans often fail in their security roles. Whenever possible, secure system designers should find ways of keeping humans out of the loop. However, there are some tasks for which feasible or cost effective alternatives to humans are not available. In these cases secure system designers should engineer their systems to support the humans in the loop and maximize their chances of performing their security-critical functions successfully. We propose a framework for reasoning about the human in the loop that provides a systematic approach to identifying potential causes for human failure. This framework can be used by system designers to identify problem areas before a system is built and proactively address deficiencies. System operators can also use this framework to analyze the root cause of security failures that have been attributed to “human error.” We provide examples to illustrate the applicability of this framework to a variety of secure systems design problems, including anti-phishing warnings and password policies

Behavioral Response to Phishing Risk

Tools that aim to combat phishing attacks must take into account how and why people fall for them in order to be effective. This study reports a pilot survey of 232 computer users to reveal predictors of falling for phishing emails, as well as trusting legitimate emails. Previous work suggests that people may be vulnerable to phishing schemes because their awareness of the risks is not linked to perceived vulnerability or to useful strategies in identifying phishing emails. In this survey, we explore what factors are associated with falling for phishing attacks in a roleplay exercise. Our data suggest that deeper understanding of the web environment, such as being able to correctly interpret URLs and understanding what a lock signifies, is associated with less vulnerability to phishing attacks. Perceived severity of the consequences does not predict behavior. These results suggest that educational efforts should aim to increase users’ intuitive understanding, rather than merely warning them about risks

Lessons Learned from the Deployment of a Smartphone-Based Access-Control System

Grey is a smartphone-based system by which a user can exercise her authority to gain access to rooms in our university building, and by which she can delegate that authority to other users.We present findings from a trial of Grey, with emphasis on how common usability principles manifest themselves in a smartphone-based security application. In particular, we demonstrate aspects of the system that gave rise to failures, misunderstandings, misperceptions, and unintended uses; network effects and new flexibility enabled by Grey; and the implications of these for user behavior.We argue that the manner in which usability principles emerged in the context of Grey can inform the design of other such applications

P3P Deployment on Websites

We studied the deployment of computer-readable privacy policies encoded using the standard W3C Platform for Privacy Preferences (P3P) format to inform questions about P3P’s usefulness to end users and researchers. We found that P3P adoption is increasing overall and that P3P adoption rates greatly vary across industries. We found that P3P had been deployed on 10% of the sites returned in the top-20 results of typical searches, and on 21% of the sites returned in the top-20 results of e-commerce searches. We examined a set of over 5,000 web sites in both 2003 and 2006 and found that P3P deployment among these sites increased over that time period, although we observed decreases in some sectors. In the Fall of 2007 we observed 470 new P3P policies created over a two month period. We found high rates of syntax errors among P3P policies, but much lower rates of critical errors that prevent a P3P user agent from interpreting them.We also found that most P3P policies have discrepancies with their natural language counterparts. Some of these discrepancies can be attributed to ambiguities, while others cause the two policies to have completely different meanings. Finally, we show that the privacy policies of P3P-enabled popular websites are similar to the privacy policies of popular websites that do not use P3P

Getting Users to Pay Attention to Anti-Phishing Education: Evaluation of Retention and Transfer

Educational materials designed to teach users not to fall for phishing attacks are widely available but are often ignored by users. In this paper, we extend an embedded training methodology using learning science principles in which phishing education is made part of a primary task for users. The goal is to motivate users to pay attention to the training materials. In embedded training, users are sent simulated phishing attacks and trained after they fall for the attacks. Prior studies tested users immediately after training and demonstrated that embedded training improved users’ ability to identify phishing emails and websites. In the present study, we tested users to determine how well they retained knowledge gained through embedded training and how well they transferred this knowledge to identify other types of phishing emails. We also compared the effectiveness of the same training materials delivered via embedded training and delivered as regular email messages. In our experiments, we found that: (a) users learn more effectively when the training materials are presented after users fall for the attack (embedded) than when the same training materials are sent by email (non-embedded); (b) users retain and transfer more knowledge after embedded training than after nonembedded training; and (c) users with higher Cognitive Reflection Test (CRT) scores are more likely than users with lower CRT scores to click on the links in the phishing emails from companies with which they have no account