The present disclosure relates to an intelligent service (e.g., a smart home, a smart building, a smart car, etc.) based on a 5G communication technology and an IoT related technology. In accordance with an embodiment of the present disclosure, a method is provided for detecting, by a web server in a wireless communication system, a malicious code which is injected into the command stream of a widget miming on a web-based OS in a device. The method includes: analyzing the widget in the web server; determining at least one invariant condition constantly maintained and conserved while the widget is running, on the basis of a result of the analyzing; generating a metadata file including data satisfying the at least one invariant condition; and associating the metadata file with the widget and providing the widget in a state in which the associated metadata file is included in the widget.