A concern about personal information confidentiality typically arises when any desktop application communicates to the external network, for example, to its producer's server for obtaining software version updates. We address this confidentiality concern of end users by an approach called shadow execution. A key property of shadow execution is that it allows applications to successfully communicate over the network while disallowing any information leaks. We describe the design and implementation of this approach for Windows applications. Experiments with our prototype implementation indicate that shadow execution allows applications to execute without inhibiting any behaviors, has acceptable performance overheads while preventing any information leaks.