CORS configuration for IIS

web.config

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <httpProtocol>
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="https://<your target domain>.slack.com" />
        <add name="Access-Control-Allow-Methods" value="GET, PUT, POST, DELETE" />
        <add name="Access-Control-Allow-Credentials" value="true" />
      </customHeaders>
    </httpProtocol>    
  </system.webServer>
  <location path="payload.exe">
    <system.webServer>
      <staticContent>
      <clientCache cacheControlMode="DisableCache" />
      </staticContent>
    </system.webServer>
  </location>
</configuration>