Concepts and technologies disclosed herein are for detecting and managing unauthorized use of cloud computing services from within an internal network of a business or other organization. A computer system may be configured to identify a plurality of Web resources that have been accessed by computing devices from within the internal network. The computer system may also be configured to obtain Internet protocol (“IP”) information from a network component of the internal network. The IP information may be used to determine whether each of the plurality of Web resources is a cloud computing service resource. The computer system may also be configured to block access to a cloud computing service resource of the plurality of Web resources upon determining that the IP information identifies the cloud computing service resource as being unauthorized.