WASHINGTON (AP) — A tool designed to help businesses protect themselves from further compromises after a global hack of Microsoft email server software has been downloaded more than 25,000 times since it was released last week. That’s according to the White House’s National Security Council. As a result, the number of vulnerable systems has fallen by 45%. The one-click Microsoft tool was created to protect against cyberattacks and to scan systems for compromises and fix them. The tool was developed after a massive hack affecting an estimated tens of thousands of users of servers running Microsoft’s Exchange email program.