Hi,

I'm having trouble running untrusted code inside a sandboxed AppDomain, and
I was hoping that someone could help me!

The code is user-supplied, and so I want my Winform application to run the
code in a seperate AppDomain without any more permissions than given in the
Internet permission set.

This seems to work okay, except for when the code contains Winform code -
such as MessageBox.Show. The following exception is thrown when
UntrustedMethod is called in my sandboxed appdomain:

 System.Security.Policy.PolicyException: Required permissions cannot be
acquired.

I've tried adding UIPermissionWindow.AllWindows, but that doesn't seem to
help.

Thanks in advance for your help,

Kirk

using System;
using System.Collections;
using System.Reflection;
using System.Security;
using System.Security.Permissions;
using System.Security.Policy;

namespace Sandbox
{

interface ISandbox {
 void UntrustedMethod();
}

[Serializable]
class Sandbox : MarshalByRefObject, ISandbox
{
 [STAThread]
 static void Main(string[] args) {
  AppDomainSetup setup = new AppDomainSetup();
  setup.ApplicationName = "Sandbox secure appdomain";
  setup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory;

  AppDomain sandboxAppDomain = AppDomain.CreateDomain("Sandbox secure
appdomain", null, setup);

  // Load the internet permission set, and add UIPermission.AllWindows
  NamedPermissionSet permSet = FindNamedPermissionSet("Internet");

  permSet.AddPermission(new UIPermission(UIPermissionWindow.AllWindows));

  PolicyStatement polState = new PolicyStatement(permSet);
  PolicyLevel domainPolicy = PolicyLevel.CreateAppDomainLevel();
  AllMembershipCondition allCodeMC = new AllMembershipCondition();
  CodeGroup allCodeCG = new UnionCodeGroup(allCodeMC,polState);
  domainPolicy.RootCodeGroup = allCodeCG;
  sandboxAppDomain.SetAppDomainPolicy(domainPolicy);

  // Try running MessageBox.Show in the appdomain
  try {
   Sandbox sandboxObject =
(Sandbox)sandboxAppDomain.CreateInstanceAndUnwrap(
    Assembly.GetExecutingAssembly().FullName,
    "Sandbox.Sandbox");

   sandboxObject.UntrustedMethod();
  } catch (Exception ex) {
   Console.WriteLine(ex.ToString());
  }

  Console.ReadLine();
 }

 private static NamedPermissionSet FindNamedPermissionSet(string name) {
  IEnumerator policyEnumerator = SecurityManager.PolicyHierarchy();

  while (policyEnumerator.MoveNext()) {
   PolicyLevel currentLevel = (PolicyLevel)policyEnumerator.Current;

   if (currentLevel.Label == "Machine") {
    IList namedPermissions = currentLevel.NamedPermissionSets;
    IEnumerator namedPermission = namedPermissions.GetEnumerator();

    while (namedPermission.MoveNext()) {
     if (((NamedPermissionSet)namedPermission.Current).Name == name) {
      return ((NamedPermissionSet)namedPermission.Current);
     }
    }
   }
  }
  return null;
 }

 /// This is an untrusted method executed seperately from the rest of the
application
 public void UntrustedMethod() {
  System.Windows.Forms.MessageBox.Show(AppDomain.CurrentDomain.FriendlyName);
 }
}
}