wcf user account

I have a WCF service that needs to access some files outside i开发者_如何学Pythonts folder. IIS7 does not allow to access the files. I guess I need give a read permission to these files. What user account does wcf use?

The account that WCF uses depends on how it is hosted and configured. If it is hosted in IIS, for instance, it uses the user account of the Application Pool serving the virtual directory in which the .svc files are placed.