ABADev blog

function IsAdmin: Boolean; 
const 
  DOMAIN_ALIAS_RID_ADMINS = $00000220; 
  SECURITY_NT_AUTHORITY: TSIDIdentifierAuthority = (Value: (0, 0, 0, 0, 0, 5)); 
  SECURITY_BUILTIN_DOMAIN_RID = $00000020; 
var 
  hAccessToken: THandle; 
  ptgGroups: PTokenGroups; 
  dwInfoBufferSize: DWORD; 
  psidAdministrators: PSID; 
  x: Integer; 
  bSuccess: BOOL; 
begin 
  Result := False; 
  bSuccess := OpenThreadToken(GetCurrentThread, TOKEN_QUERY, True, 
    hAccessToken); 
  if not bSuccess then 
  begin 
    if GetLastError = ERROR_NO_TOKEN then 
    bSuccess := OpenProcessToken(GetCurrentProcess, TOKEN_QUERY, 
                                  hAccessToken); 
  end; 
  if bSuccess then 
  begin 
    GetMem(ptgGroups, 1024); 
    bSuccess := GetTokenInformation(hAccessToken, TokenGroups, 
                                    ptgGroups, 1024, dwInfoBufferSize); 
    CloseHandle(hAccessToken); 
    if bSuccess then 
    begin 
      AllocateAndInitializeSid(SECURITY_NT_AUTHORITY, 2, 
        SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS, 
        0, 0, 0, 0, 0, 0, psidAdministrators); 
      {$R-} 
      for x := 0 to ptgGroups.GroupCount - 1 do 
        if EqualSid(psidAdministrators, ptgGroups.Groups[x].Sid) then 
        begin 
          Result := True; 
          Break; 
        end; 
      {$R+} 
      FreeSid(psidAdministrators); 
    end; 
    FreeMem(ptgGroups); 
  end; 
end;