Auf Administratorrechte prüfen

function IsAdmin: Boolean;
const
  SECURITY_NT_AUTHORITY: TSIDIdentifierAuthority =
  (Value: (0, 0, 0, 0, 0, 5));
  SECURITY_BUILTIN_DOMAIN_RID = $00000020;
  DOMAIN_ALIAS_RID_ADMINS     = $00000220;

var
  hAccessToken: THandle;
  ptgGroups: PTokenGroups;
  dwInfoBufferSize: DWORD;
  psidAdministrators: PSID;
  x: Integer;
  bSuccess: BOOL;
begin
  Result := False;
  bSuccess:=False;
  ptgGroups:=nil;
  psidAdministrators:=nil;
  try
    bSuccess := OpenThreadToken(GetCurrentThread, TOKEN_QUERY, True,
      hAccessToken);
    if not bSuccess then
    begin
      if GetLastError = ERROR_NO_TOKEN then
      bSuccess := OpenProcessToken(GetCurrentProcess, TOKEN_QUERY,
        hAccessToken);
    end;
    if bSuccess then
    begin
      GetMem(ptgGroups, 1024);
      bSuccess := GetTokenInformation(hAccessToken, TokenGroups,
        ptgGroups, 1024, dwInfoBufferSize);
      if bSuccess then
      begin
        AllocateAndInitializeSid(SECURITY_NT_AUTHORITY, 2,
          SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS,
          0, 0, 0, 0, 0, 0, psidAdministrators);
        {$R-}
        for x := 0 to ptgGroups.GroupCount - 1 do
          if EqualSid(psidAdministrators, ptgGroups.Groups[x].Sid) then
          begin
            Result := True;
            Break;
          end;
        {$R+}
      end;
    end;
  finally
    if bSuccess then
      CloseHandle(hAccessToken);
    if Assigned(ptgGroups) then
      FreeMem(ptgGroups);
    if Assigned(psidAdministrators) then
      FreeSid(psidAdministrators);
  end;
end;