Between October 2020 and February 2021, Unit 42 researchers periodically scanned and analyzed unsecured Kubernetes (also known as k8s) clusters on the internet. Kubernetes clusters can and should be configured for greater security, but when left unsecured, these clusters can be accessed anonymously by anyone who knows their IPs, ports and APIs. Researchers identified 2,100 unsecured Kubernetes clusters that consist of 5,300 nodes, 31,340 CPUs and 75,270 pods. A wide range of applications were seen running in these unsecured clusters, operated by organizations in sectors including e-commerce, finance and healthcare. The abundant computational resources and large amount of sensitive data in the applications – such as API tokens, database credentials, source code and personally identifiable information (PII) – make these unsecured clusters attractive targets to adversaries. The biggest cluster that researchers encountered had more than 500 nodes and 2,000 active pods.