c# - Detect if running as Administrator with or without elevated privileges?

Question

I have an application that needs to detect whether or not it is running with elevated privileges or not. I currently have code set up like this:

static bool IsAdministrator()
{
    WindowsIdentity identity = WindowsIdentity.GetCurrent();
    WindowsPrincipal principal = new WindowsPrincipal(identity);
    return principal.IsInRole (WindowsBuiltInRole.Administrator);
}

This works to detect if a user is an administrator or not, but doesn't work if running as an administrator without elevation. (For example in vshost.exe).

How can I determine whether or not elevation is [already in force or] possible?

Answer 1

Try this out:

using Microsoft.Win32;
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Security.Principal;

public static class UacHelper
{
    private const string uacRegistryKey = "Software\Microsoft\Windows\CurrentVersion\Policies\System";
    private const string uacRegistryValue = "EnableLUA";

    private static uint STANDARD_RIGHTS_READ = 0x00020000;
    private static uint TOKEN_QUERY = 0x0008;
    private static uint TOKEN_READ = (STANDARD_RIGHTS_READ | TOKEN_QUERY);

    [DllImport("advapi32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool OpenProcessToken(IntPtr ProcessHandle, UInt32 DesiredAccess, out IntPtr TokenHandle);

    [DllImport("advapi32.dll", SetLastError = true)]
    public static extern bool GetTokenInformation(IntPtr TokenHandle, TOKEN_INFORMATION_CLASS TokenInformationClass, IntPtr TokenInformation, uint TokenInformationLength, out uint ReturnLength);

    public enum TOKEN_INFORMATION_CLASS
    {
        TokenUser = 1,
        TokenGroups,
        TokenPrivileges,
        TokenOwner,
        TokenPrimaryGroup,
        TokenDefaultDacl,
        TokenSource,
        TokenType,
        TokenImpersonationLevel,
        TokenStatistics,
        TokenRestrictedSids,
        TokenSessionId,
        TokenGroupsAndPrivileges,
        TokenSessionReference,
        TokenSandBoxInert,
        TokenAuditPolicy,
        TokenOrigin,
        TokenElevationType,
        TokenLinkedToken,
        TokenElevation,
        TokenHasRestrictions,
        TokenAccessInformation,
        TokenVirtualizationAllowed,
        TokenVirtualizationEnabled,
        TokenIntegrityLevel,
        TokenUIAccess,
        TokenMandatoryPolicy,
        TokenLogonSid,
        MaxTokenInfoClass
    }

    public enum TOKEN_ELEVATION_TYPE
    {
        TokenElevationTypeDefault = 1,
        TokenElevationTypeFull,
        TokenElevationTypeLimited
    }

    public static bool IsUacEnabled
    {
        get
        {
            RegistryKey uacKey = Registry.LocalMachine.OpenSubKey(uacRegistryKey, false);
            bool result = uacKey.GetValue(uacRegistryValue).Equals(1);
            return result;
        }
    }

    public static bool IsProcessElevated
    {
        get
        {
            if (IsUacEnabled)
            {
                IntPtr tokenHandle;
                if (!OpenProcessToken(Process.GetCurrentProcess().Handle, TOKEN_READ, out tokenHandle))
                {
                    throw new ApplicationException("Could not get process token.  Win32 Error Code: " + Marshal.GetLastWin32Error());
                }

                TOKEN_ELEVATION_TYPE elevationResult = TOKEN_ELEVATION_TYPE.TokenElevationTypeDefault;

                int elevationResultSize = Marshal.SizeOf((int)elevationResult);
                uint returnedSize = 0;
                IntPtr elevationTypePtr = Marshal.AllocHGlobal(elevationResultSize);

                bool success = GetTokenInformation(tokenHandle, TOKEN_INFORMATION_CLASS.TokenElevationType, elevationTypePtr, (uint)elevationResultSize, out returnedSize);
                if (success)
                {
                    elevationResult = (TOKEN_ELEVATION_TYPE)Marshal.ReadInt32(elevationTypePtr);
                    bool isProcessAdmin = elevationResult == TOKEN_ELEVATION_TYPE.TokenElevationTypeFull;
                    return isProcessAdmin;
                }
                else
                {
                    throw new ApplicationException("Unable to determine the current elevation.");
                }
            }
            else
            {
                WindowsIdentity identity = WindowsIdentity.GetCurrent();
                WindowsPrincipal principal = new WindowsPrincipal(identity);
                bool result = principal.IsInRole(WindowsBuiltInRole.Administrator);
                return result;
            }
        }
    }
}