different results for web and desktop applications for same code

Question

I have the following piece of code.

It is returning different results when running on the same machine in case of web and desktop applications.

Here is my code. Please guide me on what to do regarding this???

    var searcher = new ManagementObjectSearcher("SELECT * FROM Win32_PhysicalMedia");

    return (from ManagementObject wmiHD in searcher.Get()
            select wmiHD["SerialNumber"] == null ? "VM HD" : wmiHD["SerialNumber"].ToString()).ToList();

Here is a LINQ-free version of the same code

    var hdCollection = new List<string>();
    var searcher = new ManagementObjectSearcher("SELECT * FROM Win32_PhysicalMedia");

    foreach (ManagementObject wmiHD in searcher.Get())
    {
        // get the hardware serial no.
        if (wmiHD["SerialNumber"] == null)
        {
            hdCollection.Add("VM HD");
        }
        else
        {
            hdCollection.Add(wmiHD["SerialNumber"].ToString());
        }
    }
    return hdCollection;

Answer 1

That could possibly be caused by two things:

• web server runs with different user account (probably NetworkService) http://www.bluevisionsoftware.com/WebSite/TipsAndTricksDetails.aspx?Name=AspNetAccount

• web server runs code without Fulltrust permissions (probably medium trust) http://discussion.accuwebhosting.com/iis-web-server/993-how-grant-full-trust-mode-domain-asp-net-2-0-iis-6-0-a.html

Both actions can compromise security, but the first one gives more choices to fix this by setting ACLs.