[Background] Personal software configurations, known as \emph{dotfiles}, are increasingly being shared in public repositories.

[Aim] To understand the security and privacy implications of this phenomenon, we conducted a large-scale analysis of dotfiles repositories on GitHub. Furthermore, we surveyed repository owners to understand people’s motivations for sharing dotfiles and their awareness of the security implications.

[Method] Our mixed-method approach, therefore, consisted of two parts. We mined 124230 public dotfiles repositories and inductively searched them for security and privacy flaws. We then conducted a survey (n=1650) of repository owners to disclose our findings and learn more about the problems and implications.

[Results] We found that 73.6% of repositories leak potentially sensitive information, most commonly email addresses (of which we found 1.2 million), but also RSA private keys, API keys, installed software versions, browsing history, and even mail client inboxes. In addition, we found that sharing is mainly ideological (an end in itself) and to show off (``ricing''), in addition to easing machine setup. Most users are confident about the contents of their files and claim to understand the security implications. In response to our disclosures, a small minority (2.2%) will make their repositories private or delete them, but the majority of respondents will continue sharing their dotfiles after taking appropriate actions.

[Conclusions] Dotfiles repositories are a great tool for developers to share knowledge and communicate – if done correctly. We provide recommendations for users and platforms to make them more secure. Specifically, tools should be used to manage dotfiles. In addition platforms should work on more sophisticated tests, to find weaknesses automatically and inform the users or control the damage.