Systems for secure cloud-based collaboration over shared objects. Embodiments operate within systems in a cloud-based environment, wherein one or more servers are configured to interface with storage devices that store objects accessible by one or more users. A process receives an electronic message comprising a user request to access an object. Before providing user access to the object, the system generates a requestor-specific steganographic message that is derived from some portion of requestor identification information and/or other user attributes, and/or object storage parameters. Various forms of a requestor-specific steganographic message are applied to selected portions of the object to generate a requestor-specific protected object, which is then provided to the requestor. A web crawler can identify posted unauthorized protected object disclosures. Using quantitative calculations and/or heuristics together with requestor-specific aspects of the embedded steganographic message, the source of the unauthorized disclosure can be identified.