Despite their well-known security problems, passwords are still the incumbent authentication method for virtually all online services. To remedy the situation, users are very often referred to password managers as a solution to the password reuse and weakness problems. However, to date, the actual impact of password managers on password strength and reuse has not been studied systematically. We provide the first large-scale study of the password managers' influence on users' real-life passwords. By combining qualitative data on users' password creation and management strategies, collected from 476 participants of an online survey, with quantitative data (incl. password metrics and entry methods) collected in situ with a browser plugin from 170 users, we were able to gain a more complete picture of the factors that influence our participants' password strength and reuse. Our approach allows us to quantify for the first time that password managers indeed influence the password security, however, whether this influence is beneficial or aggravating existing problems depends on the users' strategies and how well the manager supports the users' password management right from the time of password creation. Given our results, we think research should further investigate how managers can better support users' password strategies in order to improve password security as well as stop aggravating the existing problems.
27th USENIX Security Symposium (USENIX Security 18)