ASP.NET and SharePoint Security Policies

You can specify a level of trust that corresponds to a predefined set of permissions for ASP.NET applications. By default, ASP.NET defines the following trust levels:

• Full
• High
• Medium
• Low
• Minimal

With the exception of the Full trust level, all trust levels grant only partial trust to the application folder of a virtual server instance. For more information on the ASP.NET trust levels, see Code Access Security for ASP.NET.
Additionally, Windows SharePoint Services defines two trust levels of its own:

• WSS_Minimal
• WSS_Medium

The trust levels extend the Minimal and Medium trust levels of ASP.NET for Windows SharePoint Services. The trust levels are defined in security policy files, wss_minimaltrust.config and wss_mediumtrust.config. By default, Windows SharePoint Services stores these files in the following location:
local_drive:\Program Files\Common Files\Microsoft Shared\web server extensions\60\config
By default, when you extend a virtual server with Windows SharePoint Services, Windows SharePoint Services sets the trust level to WSS_Minimal. This helps provide a secure trust level in which assemblies operate with the smallest set of permissions required for code to execute.
The following table outlines the specific permissions granted with the custom security policy files included with Windows SharePoint Services.

Permission	WSS_Medium trust level	WSS_Minimal trust level
AspNetHostingPermission	Medium	Minimal
Environment	Read: TEMP, TMP, OS, USERNAME, COMPUTERNAME
FileIO	Read, Write, Append, PathDiscovery:Application Directory
IsolatedStorage	AssemblyIsolationByUser, Unrestricted UserQuota
Reflection
Registry
Security	Execution, Assertion, ControlPrincipal, ControlThread, RemotingConfiguration	Execution
Socket
WebPermission	Connect to origin host (if configured)
DNS	Unrestricted
Printing	Default printing
OleDBPermission
SqlClientPermission	AllowBlankPassword=false
EventLog
Message Queue
Service Controller
Performance Counters
Directory Service
SharePointPermission	ObjectModel = true
WebPartPermission	Connections = true	Connections = true

Note   By default, Windows SharePoint Services does not grant access to the Microsoft SharePoint object model. To grant access, you must raise the associated trust level by one of several methods. The next section discusses these methods.