Cloud storage services are gaining popularity due to their flexibility, elasticity, and support to a growing need of data storage at a very accessible price, around $0.02 per GigaByte (GB) each month. Thus, more and more companies and users are relying on cloud providers to store their files. This project will study the four main cloud storage providers: Amazon Web Services (AWS), Google Cloud, IBM Cloud and Microsoft's Azure. After understanding how each cloud provider works, a scanning tool was developed to search all four providers for public objects. To make sure companies and administrators understand the utility of the tool, privacy settings and permissions are commented, also commenting how and why previous data leakage occurred. The tool has been tested and the results obtained show that there is a lot of sensitive data available to the public. With the help of the developed tool, penetration testers can help companies by making sure that no sensitive data is publicly available.