Detect if running as Administrator with or without

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

Here is a modified version of this answer to include things like the proper disposing of resources and handling of Domain Administrators.

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("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool CloseHandle(IntPtr hObject);

    [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
        {
            using (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 = IntPtr.Zero;
                if (!OpenProcessToken(Process.GetCurrentProcess().Handle, TOKEN_READ, out tokenHandle))
                {
                    throw new ApplicationException("Could not get process token.  Win32 Error Code: " +
                                                   Marshal.GetLastWin32Error());
                }

                try
                {
                    TOKEN_ELEVATION_TYPE elevationResult = TOKEN_ELEVATION_TYPE.TokenElevationTypeDefault;

                    int elevationResultSize = Marshal.SizeOf(typeof(TOKEN_ELEVATION_TYPE));
                    uint returnedSize = 0;

                    IntPtr elevationTypePtr = Marshal.AllocHGlobal(elevationResultSize);
                    try
                    {
                        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.");
                        }
                    }
                    finally
                    {
                        if (elevationTypePtr != IntPtr.Zero)
                            Marshal.FreeHGlobal(elevationTypePtr);
                    }
                }
                finally
                {
                    if (tokenHandle != IntPtr.Zero)
                        CloseHandle(tokenHandle);
                }
            }
            else
            {
                WindowsIdentity identity = WindowsIdentity.GetCurrent();
                WindowsPrincipal principal = new WindowsPrincipal(identity);
                bool result = principal.IsInRole(WindowsBuiltInRole.Administrator) 
                           || principal.IsInRole(0x200); //Domain Administrator
                return result;
            }
        }
    }
}

Answer 2

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;
            }
        }
    }
}

Answer 3

In .net Framwork 4.5 I found another method that works for me. In relation to the following script that can be found here here (in German)

 rem --- Admintest.bat ---
 whoami /groups | find "S-1-5-32-544" > nul
 if errorlevel 1 goto ende
 echo Benutzer %username% ist lokaler Administrator.
 :ende

In C# it looks like this:

    private bool IsAdmin
    {
        get
        {
            WindowsIdentity identity = WindowsIdentity.GetCurrent();
            if (identity != null)
            {
               WindowsPrincipal principal = new WindowsPrincipal(identity);
               List<Claim> list = new List<Claim>(principal.UserClaims);
               Claim c = list.Find(p => p.Value.Contains("S-1-5-32-544"));
               if (c != null)
                  return true;
            }
            return false;
        }
    }

But in .net < 4.5 the WindowsPrincipal class does not contain the UserClaims property and I found no way to get this information.

Answer 4

(new answer six years after the question was asked)

Disclaimer: This is just something that happened to work on my particular OS with my particular settings with my particular user:

using System.Security.Principal;

// ...

    static bool IsElevated
    {
      get
      {
        return WindowsIdentity.GetCurrent().Owner
          .IsWellKnown(WellKnownSidType.BuiltinAdministratorsSid);
      }
    }

So when I run this "Run as administrator", the property get accessor returns true. When running normally (even if my user "is" administrator, just not running this particular application "as administrator"), it returns false.

This seems much simpler than many other answers.

I have no idea if there are cases where this fails.

PS! This also seems OK:

    static bool IsElevated
    {
      get
      {
        var id = WindowsIdentity.GetCurrent();
        return id.Owner != id.User;
      }
    }

Answer 5

The CodePlex project UAChelper has code that checks on elevation in UserAccountControl.cpp UserAccountControl::IsUserAdmin, that checks if UAC is enabled and then checks if process is elevated.

bool UserAccountControl::IsCurrentProcessElevated::get()
{
    return GetProcessTokenElevationType() == TokenElevationTypeFull;    //elevated
}

from the function:

int UserAccountControl::GetProcessTokenElevationType()
{
    HANDLE hToken;
    try
    {
        if (!OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &hToken))
            throw gcnew Win32Exception(GetLastError());

        TOKEN_ELEVATION_TYPE elevationType;
        DWORD dwSize;
        if (!GetTokenInformation(hToken, TokenElevationType, &elevationType, sizeof(elevationType), &dwSize))
            throw gcnew Win32Exception(GetLastError());

        return elevationType;
    }
    finally
    {
        CloseHandle(hToken);
    }
}

Answer 6

Using TokenElevationType would work, but if you PInvoke CheckTokenMembership() against the admin group SID, your code would also work when UAC is off and on 2000/XP/2003 and will also handle deny SID's.

There is also a IsUserAnAdmin() function that does the CheckTokenMembership check for you, but MSDN says it might not be there forever