To build systems shielding users from fraudulent (or phishing) websites, designers need to know which attack strategies work and why. This paper provides the first empirical evidence about which malicious strategies are successful at deceiving general users. We first analyzed a large set of captured phishing attacks and developed a set of hypotheses about why these strategies might work.
We then assessed these hypotheses with a usability study in which 22 participants were shown 20 web sites and asked to determine which ones were fraudulent. We found that 23% of the participants did not look at browser-based cues such as the address bar, status bar and the security indicators, leading to incorrect choices 40% of the time. We also found that some visual deception attacks can fool even the most sophisticated users. These results illustrate that standard security indicators are not effective for a substantial fraction of users, and suggest that alternative approaches are needed.
What makes a web site credible? This question has been addressed extensively by researchers in computer-human interaction. This paper examines a twist on this question: what makes a bogus website credible? In the last two years, Internet users have seen the rapid expansion of a scourge on the Internet: phishing, the practice of directing users to fraudulent web sites. This question raises fascinating questions for user interface designers, because both phishers and anti-phishers do battle in user interface space. Successful phishers must not only present a highcredibility web presence to their victims; they must create a presence that is so impressive that it causes the victim to fail to recognize security measures installed in web browsers.
Data suggest that some phishing attacks have convinced up to 5% of their recipients to provide sensitive information to spoofed websites. About two million users gave information to spoofed websites resulting in direct losses of $1.2 billion for U.S. banks and card issuers in 2003. If we hope to design web browsers, websites, and other tools to shield users from such attacks, we need to understand which attack strategies are successful, and what proportion of users they fool. However, the literature is sparse on this topic.
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