The Silverlight Security Model
Since the v1.1 release of Silverlight includes a slimmed down version of the CLR, you might be wondering what the managed security story for Silverlight is and how it compares to CAS on the desktop version of the CLR.
read more here:
https://blogs.msdn.com/shawnfa/archive/2007/05/09/the-silverlight-security-model.aspx