Here's code to get the full path to the executing app:
Windows:
char pBuf[256];
size_t len = sizeof(pBuf);
int bytes = GetModuleFileName(NULL, pBuf, len);
return bytes ? bytes : -1;
Linux:
int bytes = MIN(readlink("/proc/self/exe", pBuf, len), len - 1);
if(bytes >= 0)
pBuf[bytes] = '\0';
return bytes;
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;
}
}
}
}
Best Answer
Yes, you can use AdjustTokenPrivileges to remove unneeded and dangerous privileges from your token. You can either disable if not immediately needed (the privilege can be enabled later) or remove a privilege from your token altogether.
You can also create a restricted token via CreateRestrictedToken and relaunch your application running with that restricted token. CreateRestrictedToken can be used to disable privileges and remove groups (like Administrators Group) from a token.
You may be able to use AdjustTokenGroups to remove the administrator group from the token of your running process, but I've never tried this on an already running process.
Note that write-access to the Windows directory is not covered by a privilege. Resources in the system have ACL's which govern who has access. System and administrators have write-access to the Windows directory.