Nowadays, security incidents have become a familiar “nuisance,” and they regularly lead to the exposure of private and sensitive data. The root causes for such incidents are rarely complex attacks. Instead, the attacks are straight-forward, and they are enabled by simple misconfigurations, such as authentication not being required, or security updates not being installed. For example, the leak of over 140 million Americans’ private data from Equifax’s systems ranks among most severe misconfigurations in recent history: The underlying vulnerability was long known, and a security patch had been readily available for months, but it was never applied. Ultimately, Equifax blamed an employee for forgetting to update the affected system, highlighting the personal responsibility of that operator. In this paper, we investigate the operators’ perspective on security misconfigurations to approach the human component of this class of security issues. We focus our analysis on system operators, as although they are the relevant actors managing the affected systems, they have not yet received significant attention by prior research. We follow an inductive approach and apply a multi-step empirical methodology: (i) a qualitative study to understand how to approach the target group and measure the misconfiguration phenomenon, and (ii) a quantitative survey rooted in the qualitative data. We then provide the first analysis of system operators’ perspective on security misconfigurations, and we determine the factors that operators perceive as the root causes. Based on our findings, we provide practical recommendations on how to reduce security misconfigurations’ frequency and impact. @en