In .NET/C# test if process has administrative privileges

Is there a canonical way to test to see if the process has administrative privileges on a machine?

I'm going to be starting a long running process, and much later in the process' lifetime it's going to attempt some things that require admin privileges.

I'd like to be able to test up front if the process has those rights rather than later on.

Solution 1:

This will check if user is in the local Administrators group (assuming you're not checking for domain admin permissions)

using System.Security.Principal;

public bool IsUserAdministrator()
{
    //bool value to hold our return value
    bool isAdmin;
    WindowsIdentity user = null;
    try
    {
        //get the currently logged in user
        user = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal(user);
        isAdmin = principal.IsInRole(WindowsBuiltInRole.Administrator);
    }
    catch (UnauthorizedAccessException ex)
    {
        isAdmin = false;
    }
    catch (Exception ex)
    {
        isAdmin = false;
    }
    finally
    {
        if (user != null)
            user.Dispose();
    }
    return isAdmin;
}

Solution 2:

Starting with Wadih M's code, I've got some additional P/Invoke code to try and handle the case of when UAC is on.

http://www.davidmoore.info/blog/2011/06/20/how-to-check-if-the-current-user-is-an-administrator-even-if-uac-is-on/

First, we’ll need some code to support the GetTokenInformation API call:

[DllImport("advapi32.dll", SetLastError = true)]
static extern bool GetTokenInformation(IntPtr tokenHandle, TokenInformationClass tokenInformationClass, IntPtr tokenInformation, int tokenInformationLength, out int returnLength);

/// <summary>
/// Passed to <see cref="GetTokenInformation"/> to specify what
/// information about the token to return.
/// </summary>
enum TokenInformationClass
{
     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
}

/// <summary>
/// The elevation type for a user token.
/// </summary>
enum TokenElevationType
{
    TokenElevationTypeDefault = 1,
    TokenElevationTypeFull,
    TokenElevationTypeLimited
}

Then, the actual code to detect if the user is an Administrator (returning true if they are, otherwise false).

var identity = WindowsIdentity.GetCurrent();
if (identity == null) throw new InvalidOperationException("Couldn't get the current user identity");
var principal = new WindowsPrincipal(identity);

// Check if this user has the Administrator role. If they do, return immediately.
// If UAC is on, and the process is not elevated, then this will actually return false.
if (principal.IsInRole(WindowsBuiltInRole.Administrator)) return true;

// If we're not running in Vista onwards, we don't have to worry about checking for UAC.
if (Environment.OSVersion.Platform != PlatformID.Win32NT || Environment.OSVersion.Version.Major < 6)
{
     // Operating system does not support UAC; skipping elevation check.
     return false;
}

int tokenInfLength = Marshal.SizeOf(typeof(int));
IntPtr tokenInformation = Marshal.AllocHGlobal(tokenInfLength);

try
{
    var token = identity.Token;
    var result = GetTokenInformation(token, TokenInformationClass.TokenElevationType, tokenInformation, tokenInfLength, out tokenInfLength);

    if (!result)
    {
        var exception = Marshal.GetExceptionForHR( Marshal.GetHRForLastWin32Error() );
        throw new InvalidOperationException("Couldn't get token information", exception);
    }

    var elevationType = (TokenElevationType)Marshal.ReadInt32(tokenInformation);

    switch (elevationType)
    {
        case TokenElevationType.TokenElevationTypeDefault:
            // TokenElevationTypeDefault - User is not using a split token, so they cannot elevate.
            return false;
        case TokenElevationType.TokenElevationTypeFull:
            // TokenElevationTypeFull - User has a split token, and the process is running elevated. Assuming they're an administrator.
            return true;
        case TokenElevationType.TokenElevationTypeLimited:
            // TokenElevationTypeLimited - User has a split token, but the process is not running elevated. Assuming they're an administrator.
            return true;
        default:
            // Unknown token elevation type.
            return false;
     }
}
finally
{    
    if (tokenInformation != IntPtr.Zero) Marshal.FreeHGlobal(tokenInformation);
}

Solution 3:

If you want to make sure your solution works in Vista UAC, and have .Net Framework 3.5 or better, you might want to use the System.DirectoryServices.AccountManagement namespace. Your code would look something like:

bool isAllowed = false;
using (PrincipalContext pc = new PrincipalContext(ContextType.Machine, null))
{
    UserPrincipal up = UserPrincipal.Current;
    GroupPrincipal gp = GroupPrincipal.FindByIdentity(pc, "Administrators");
    if (up.IsMemberOf(gp))
        isAllowed = true;
}

Solution 4:

Tried Erwin's code but it didn't compile.

Got it to work like this:

[DllImport("shell32.dll")] public static extern bool IsUserAnAdmin();