Question

I have a multi-tenant application that may run arbitrary workflows as needed.

I plan on using the workflow designer to create these workflows, but even if I limit the Activities in the Toolbox, that doesn’t prevent a malicious user from editing his own XAML file, doing activities I’d rather them not (specifically calling out to the .NET framework)

For a given workflow, how do I verify that the only actions being used are those I approve of? Is an XPath query the only way, or is there a feature within WF that will validate this?

If you need a visual introduction to what I’m looking for here is a sample project and video referring to it.

Answer 1

I’d just load the workflows in a sandboxed AppDomain. You can Use the GetStandardSandbox static method of the SecurityManager to set this up relatively easily (and safely).

Of course, I haven’t actually done this yet, but I’m definitely thinking about adding some of this to my current WF code (which does use AppDomains to isolate execution of workflows from my application).